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2009 lines
63 KiB
2009 lines
63 KiB
# SPDX-License-Identifier: GPL-2.0-only |
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config CC_VERSION_TEXT |
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string |
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default "$(CC_VERSION_TEXT)" |
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help |
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This is used in unclear ways: |
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|
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- Re-run Kconfig when the compiler is updated |
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The 'default' property references the environment variable, |
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CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd. |
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When the compiler is updated, Kconfig will be invoked. |
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- Ensure full rebuild when the compiler is updated |
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include/linux/compiler-version.h contains this option in the comment |
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line so fixdep adds include/config/CC_VERSION_TEXT into the |
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auto-generated dependency. When the compiler is updated, syncconfig |
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will touch it and then every file will be rebuilt. |
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config CC_IS_GCC |
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def_bool $(success,test "$(cc-name)" = GCC) |
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config GCC_VERSION |
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int |
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default $(cc-version) if CC_IS_GCC |
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default 0 |
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config CC_IS_CLANG |
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def_bool $(success,test "$(cc-name)" = Clang) |
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config CLANG_VERSION |
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int |
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default $(cc-version) if CC_IS_CLANG |
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default 0 |
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config AS_IS_GNU |
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def_bool $(success,test "$(as-name)" = GNU) |
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config AS_IS_LLVM |
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def_bool $(success,test "$(as-name)" = LLVM) |
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config AS_VERSION |
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int |
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# Use clang version if this is the integrated assembler |
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default CLANG_VERSION if AS_IS_LLVM |
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default $(as-version) |
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config LD_IS_BFD |
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def_bool $(success,test "$(ld-name)" = BFD) |
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config LD_VERSION |
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int |
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default $(ld-version) if LD_IS_BFD |
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default 0 |
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config LD_IS_LLD |
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def_bool $(success,test "$(ld-name)" = LLD) |
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config LLD_VERSION |
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int |
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default $(ld-version) if LD_IS_LLD |
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default 0 |
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config RUST_IS_AVAILABLE |
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def_bool $(success,$(srctree)/scripts/rust_is_available.sh) |
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help |
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This shows whether a suitable Rust toolchain is available (found). |
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Please see Documentation/rust/quick-start.rst for instructions on how |
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to satisfy the build requirements of Rust support. |
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In particular, the Makefile target 'rustavailable' is useful to check |
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why the Rust toolchain is not being detected. |
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config CC_CAN_LINK |
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bool |
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default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT |
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default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag)) |
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config CC_CAN_LINK_STATIC |
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bool |
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default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT |
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default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static) |
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config CC_HAS_ASM_GOTO_OUTPUT |
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def_bool $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null) |
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config CC_HAS_ASM_GOTO_TIED_OUTPUT |
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depends on CC_HAS_ASM_GOTO_OUTPUT |
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# Detect buggy gcc and clang, fixed in gcc-11 clang-14. |
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def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null) |
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config TOOLS_SUPPORT_RELR |
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def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh) |
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config CC_HAS_ASM_INLINE |
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def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) |
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config CC_HAS_NO_PROFILE_FN_ATTR |
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def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) |
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config PAHOLE_VERSION |
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int |
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default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) |
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config CONSTRUCTORS |
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bool |
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config IRQ_WORK |
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bool |
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config BUILDTIME_TABLE_SORT |
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bool |
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config THREAD_INFO_IN_TASK |
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bool |
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help |
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Select this to move thread_info off the stack into task_struct. To |
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make this work, an arch will need to remove all thread_info fields |
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except flags and fix any runtime bugs. |
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One subtle change that will be needed is to use try_get_task_stack() |
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and put_task_stack() in save_thread_stack_tsk() and get_wchan(). |
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menu "General setup" |
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config BROKEN |
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bool |
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config BROKEN_ON_SMP |
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bool |
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depends on BROKEN || !SMP |
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default y |
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config INIT_ENV_ARG_LIMIT |
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int |
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default 32 if !UML |
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default 128 if UML |
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help |
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Maximum of each of the number of arguments and environment |
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variables passed to init from the kernel command line. |
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config COMPILE_TEST |
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bool "Compile also drivers which will not load" |
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depends on HAS_IOMEM |
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help |
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Some drivers can be compiled on a different platform than they are |
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intended to be run on. Despite they cannot be loaded there (or even |
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when they load they cannot be used due to missing HW support), |
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developers still, opposing to distributors, might want to build such |
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drivers to compile-test them. |
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If you are a developer and want to build everything available, say Y |
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here. If you are a user/distributor, say N here to exclude useless |
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drivers to be distributed. |
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config WERROR |
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bool "Compile the kernel with warnings as errors" |
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default COMPILE_TEST |
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help |
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A kernel build should not cause any compiler warnings, and this |
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enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags |
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to enforce that rule by default. |
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However, if you have a new (or very old) compiler with odd and |
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unusual warnings, or you have some architecture with problems, |
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you may need to disable this config option in order to |
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successfully build the kernel. |
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If in doubt, say Y. |
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config UAPI_HEADER_TEST |
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bool "Compile test UAPI headers" |
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depends on HEADERS_INSTALL && CC_CAN_LINK |
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help |
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Compile test headers exported to user-space to ensure they are |
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self-contained, i.e. compilable as standalone units. |
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If you are a developer or tester and want to ensure the exported |
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headers are self-contained, say Y here. Otherwise, choose N. |
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config LOCALVERSION |
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string "Local version - append to kernel release" |
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help |
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Append an extra string to the end of your kernel version. |
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This will show up when you type uname, for example. |
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The string you set here will be appended after the contents of |
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any files with a filename matching localversion* in your |
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object and source tree, in that order. Your total string can |
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be a maximum of 64 characters. |
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config LOCALVERSION_AUTO |
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bool "Automatically append version information to the version string" |
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default y |
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depends on !COMPILE_TEST |
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help |
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This will try to automatically determine if the current tree is a |
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release tree by looking for git tags that belong to the current |
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top of tree revision. |
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A string of the format -gxxxxxxxx will be added to the localversion |
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if a git-based tree is found. The string generated by this will be |
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appended after any matching localversion* files, and after the value |
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set in CONFIG_LOCALVERSION. |
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(The actual string used here is the first eight characters produced |
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by running the command: |
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$ git rev-parse --verify HEAD |
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which is done within the script "scripts/setlocalversion".) |
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config BUILD_SALT |
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string "Build ID Salt" |
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default "" |
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help |
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The build ID is used to link binaries and their debug info. Setting |
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this option will use the value in the calculation of the build id. |
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This is mostly useful for distributions which want to ensure the |
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build is unique between builds. It's safe to leave the default. |
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config HAVE_KERNEL_GZIP |
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bool |
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config HAVE_KERNEL_BZIP2 |
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bool |
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config HAVE_KERNEL_LZMA |
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bool |
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config HAVE_KERNEL_XZ |
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bool |
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config HAVE_KERNEL_LZO |
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bool |
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config HAVE_KERNEL_LZ4 |
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bool |
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config HAVE_KERNEL_ZSTD |
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bool |
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config HAVE_KERNEL_UNCOMPRESSED |
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bool |
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choice |
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prompt "Kernel compression mode" |
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default KERNEL_GZIP |
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depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED |
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help |
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The linux kernel is a kind of self-extracting executable. |
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Several compression algorithms are available, which differ |
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in efficiency, compression and decompression speed. |
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Compression speed is only relevant when building a kernel. |
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Decompression speed is relevant at each boot. |
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If you have any problems with bzip2 or lzma compressed |
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kernels, mail me (Alain Knaff) <[email protected]>. (An older |
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version of this functionality (bzip2 only), for 2.4, was |
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supplied by Christian Ludwig) |
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High compression options are mostly useful for users, who |
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are low on disk space (embedded systems), but for whom ram |
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size matters less. |
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If in doubt, select 'gzip' |
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config KERNEL_GZIP |
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bool "Gzip" |
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depends on HAVE_KERNEL_GZIP |
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help |
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The old and tried gzip compression. It provides a good balance |
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between compression ratio and decompression speed. |
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config KERNEL_BZIP2 |
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bool "Bzip2" |
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depends on HAVE_KERNEL_BZIP2 |
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help |
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Its compression ratio and speed is intermediate. |
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Decompression speed is slowest among the choices. The kernel |
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size is about 10% smaller with bzip2, in comparison to gzip. |
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Bzip2 uses a large amount of memory. For modern kernels you |
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will need at least 8MB RAM or more for booting. |
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config KERNEL_LZMA |
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bool "LZMA" |
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depends on HAVE_KERNEL_LZMA |
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help |
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This compression algorithm's ratio is best. Decompression speed |
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is between gzip and bzip2. Compression is slowest. |
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The kernel size is about 33% smaller with LZMA in comparison to gzip. |
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config KERNEL_XZ |
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bool "XZ" |
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depends on HAVE_KERNEL_XZ |
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help |
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XZ uses the LZMA2 algorithm and instruction set specific |
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BCJ filters which can improve compression ratio of executable |
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code. The size of the kernel is about 30% smaller with XZ in |
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comparison to gzip. On architectures for which there is a BCJ |
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filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ |
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will create a few percent smaller kernel than plain LZMA. |
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The speed is about the same as with LZMA: The decompression |
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speed of XZ is better than that of bzip2 but worse than gzip |
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and LZO. Compression is slow. |
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config KERNEL_LZO |
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bool "LZO" |
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depends on HAVE_KERNEL_LZO |
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help |
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Its compression ratio is the poorest among the choices. The kernel |
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size is about 10% bigger than gzip; however its speed |
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(both compression and decompression) is the fastest. |
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config KERNEL_LZ4 |
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bool "LZ4" |
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depends on HAVE_KERNEL_LZ4 |
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help |
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LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. |
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A preliminary version of LZ4 de/compression tool is available at |
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<https://code.google.com/p/lz4/>. |
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Its compression ratio is worse than LZO. The size of the kernel |
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is about 8% bigger than LZO. But the decompression speed is |
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faster than LZO. |
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config KERNEL_ZSTD |
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bool "ZSTD" |
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depends on HAVE_KERNEL_ZSTD |
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help |
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ZSTD is a compression algorithm targeting intermediate compression |
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with fast decompression speed. It will compress better than GZIP and |
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decompress around the same speed as LZO, but slower than LZ4. You |
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will need at least 192 KB RAM or more for booting. The zstd command |
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line tool is required for compression. |
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config KERNEL_UNCOMPRESSED |
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bool "None" |
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depends on HAVE_KERNEL_UNCOMPRESSED |
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help |
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Produce uncompressed kernel image. This option is usually not what |
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you want. It is useful for debugging the kernel in slow simulation |
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environments, where decompressing and moving the kernel is awfully |
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slow. This option allows early boot code to skip the decompressor |
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and jump right at uncompressed kernel image. |
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endchoice |
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config DEFAULT_INIT |
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string "Default init path" |
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default "" |
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help |
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This option determines the default init for the system if no init= |
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option is passed on the kernel command line. If the requested path is |
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not present, we will still then move on to attempting further |
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locations (e.g. /sbin/init, etc). If this is empty, we will just use |
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the fallback list when init= is not passed. |
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config DEFAULT_HOSTNAME |
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string "Default hostname" |
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default "(none)" |
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help |
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This option determines the default system hostname before userspace |
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calls sethostname(2). The kernel traditionally uses "(none)" here, |
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but you may wish to use a different default here to make a minimal |
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system more usable with less configuration. |
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config SYSVIPC |
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bool "System V IPC" |
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help |
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Inter Process Communication is a suite of library functions and |
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system calls which let processes (running programs) synchronize and |
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exchange information. It is generally considered to be a good thing, |
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and some programs won't run unless you say Y here. In particular, if |
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you want to run the DOS emulator dosemu under Linux (read the |
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DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), |
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you'll need to say Y here. |
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You can find documentation about IPC with "info ipc" and also in |
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section 6.4 of the Linux Programmer's Guide, available from |
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<http://www.tldp.org/guides.html>. |
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config SYSVIPC_SYSCTL |
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bool |
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depends on SYSVIPC |
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depends on SYSCTL |
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default y |
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config SYSVIPC_COMPAT |
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def_bool y |
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depends on COMPAT && SYSVIPC |
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config POSIX_MQUEUE |
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bool "POSIX Message Queues" |
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depends on NET |
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help |
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POSIX variant of message queues is a part of IPC. In POSIX message |
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queues every message has a priority which decides about succession |
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of receiving it by a process. If you want to compile and run |
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programs written e.g. for Solaris with use of its POSIX message |
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queues (functions mq_*) say Y here. |
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POSIX message queues are visible as a filesystem called 'mqueue' |
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and can be mounted somewhere if you want to do filesystem |
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operations on message queues. |
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If unsure, say Y. |
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config POSIX_MQUEUE_SYSCTL |
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bool |
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depends on POSIX_MQUEUE |
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depends on SYSCTL |
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default y |
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config WATCH_QUEUE |
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bool "General notification queue" |
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default n |
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help |
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This is a general notification queue for the kernel to pass events to |
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userspace by splicing them into pipes. It can be used in conjunction |
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with watches for key/keyring change notifications and device |
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notifications. |
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See Documentation/core-api/watch_queue.rst |
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config CROSS_MEMORY_ATTACH |
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bool "Enable process_vm_readv/writev syscalls" |
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depends on MMU |
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default y |
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help |
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Enabling this option adds the system calls process_vm_readv and |
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process_vm_writev which allow a process with the correct privileges |
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to directly read from or write to another process' address space. |
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See the man page for more details. |
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config USELIB |
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bool "uselib syscall (for libc5 and earlier)" |
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default ALPHA || M68K || SPARC |
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help |
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This option enables the uselib syscall, a system call used in the |
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dynamic linker from libc5 and earlier. glibc does not use this |
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system call. If you intend to run programs built on libc5 or |
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earlier, you may need to enable this syscall. Current systems |
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running glibc can safely disable this. |
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config AUDIT |
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bool "Auditing support" |
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depends on NET |
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help |
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Enable auditing infrastructure that can be used with another |
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kernel subsystem, such as SELinux (which requires this for |
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logging of avc messages output). System call auditing is included |
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on architectures which support it. |
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config HAVE_ARCH_AUDITSYSCALL |
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bool |
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config AUDITSYSCALL |
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def_bool y |
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depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
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select FSNOTIFY |
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source "kernel/irq/Kconfig" |
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source "kernel/time/Kconfig" |
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source "kernel/bpf/Kconfig" |
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source "kernel/Kconfig.preempt" |
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menu "CPU/Task time and stats accounting" |
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config VIRT_CPU_ACCOUNTING |
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bool |
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choice |
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prompt "Cputime accounting" |
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default TICK_CPU_ACCOUNTING |
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# Kind of a stub config for the pure tick based cputime accounting |
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config TICK_CPU_ACCOUNTING |
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bool "Simple tick based cputime accounting" |
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depends on !S390 && !NO_HZ_FULL |
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help |
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This is the basic tick based cputime accounting that maintains |
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statistics about user, system and idle time spent on per jiffies |
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granularity. |
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If unsure, say Y. |
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config VIRT_CPU_ACCOUNTING_NATIVE |
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bool "Deterministic task and CPU time accounting" |
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depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
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select VIRT_CPU_ACCOUNTING |
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help |
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Select this option to enable more accurate task and CPU time |
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accounting. This is done by reading a CPU counter on each |
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kernel entry and exit and on transitions within the kernel |
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between system, softirq and hardirq state, so there is a |
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small performance impact. In the case of s390 or IBM POWER > 5, |
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this also enables accounting of stolen time on logically-partitioned |
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systems. |
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config VIRT_CPU_ACCOUNTING_GEN |
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bool "Full dynticks CPU time accounting" |
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depends on HAVE_CONTEXT_TRACKING_USER |
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depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
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depends on GENERIC_CLOCKEVENTS |
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select VIRT_CPU_ACCOUNTING |
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select CONTEXT_TRACKING_USER |
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help |
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Select this option to enable task and CPU time accounting on full |
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dynticks systems. This accounting is implemented by watching every |
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kernel-user boundaries using the context tracking subsystem. |
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The accounting is thus performed at the expense of some significant |
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overhead. |
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For now this is only useful if you are working on the full |
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dynticks subsystem development. |
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If unsure, say N. |
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endchoice |
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config IRQ_TIME_ACCOUNTING |
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bool "Fine granularity task level IRQ time accounting" |
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depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
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help |
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Select this option to enable fine granularity task irq time |
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accounting. This is done by reading a timestamp on each |
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transitions between softirq and hardirq state, so there can be a |
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small performance impact. |
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If in doubt, say N here. |
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config HAVE_SCHED_AVG_IRQ |
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def_bool y |
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depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING |
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depends on SMP |
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config SCHED_THERMAL_PRESSURE |
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bool |
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default y if ARM && ARM_CPU_TOPOLOGY |
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default y if ARM64 |
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depends on SMP |
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depends on CPU_FREQ_THERMAL |
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help |
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Select this option to enable thermal pressure accounting in the |
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scheduler. Thermal pressure is the value conveyed to the scheduler |
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that reflects the reduction in CPU compute capacity resulted from |
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thermal throttling. Thermal throttling occurs when the performance of |
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a CPU is capped due to high operating temperatures. |
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If selected, the scheduler will be able to balance tasks accordingly, |
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i.e. put less load on throttled CPUs than on non/less throttled ones. |
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This requires the architecture to implement |
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arch_update_thermal_pressure() and arch_scale_thermal_pressure(). |
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config BSD_PROCESS_ACCT |
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bool "BSD Process Accounting" |
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depends on MULTIUSER |
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help |
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If you say Y here, a user level program will be able to instruct the |
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kernel (via a special system call) to write process accounting |
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information to a file: whenever a process exits, information about |
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that process will be appended to the file by the kernel. The |
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information includes things such as creation time, owning user, |
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command name, memory usage, controlling terminal etc. (the complete |
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list is in the struct acct in <file:include/linux/acct.h>). It is |
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up to the user level program to do useful things with this |
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information. This is generally a good idea, so say Y. |
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config BSD_PROCESS_ACCT_V3 |
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bool "BSD Process Accounting version 3 file format" |
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depends on BSD_PROCESS_ACCT |
|
default n |
|
help |
|
If you say Y here, the process accounting information is written |
|
in a new file format that also logs the process IDs of each |
|
process and its parent. Note that this file format is incompatible |
|
with previous v0/v1/v2 file formats, so you will need updated tools |
|
for processing it. A preliminary version of these tools is available |
|
at <http://www.gnu.org/software/acct/>. |
|
|
|
config TASKSTATS |
|
bool "Export task/process statistics through netlink" |
|
depends on NET |
|
depends on MULTIUSER |
|
default n |
|
help |
|
Export selected statistics for tasks/processes through the |
|
generic netlink interface. Unlike BSD process accounting, the |
|
statistics are available during the lifetime of tasks/processes as |
|
responses to commands. Like BSD accounting, they are sent to user |
|
space on task exit. |
|
|
|
Say N if unsure. |
|
|
|
config TASK_DELAY_ACCT |
|
bool "Enable per-task delay accounting" |
|
depends on TASKSTATS |
|
select SCHED_INFO |
|
help |
|
Collect information on time spent by a task waiting for system |
|
resources like cpu, synchronous block I/O completion and swapping |
|
in pages. Such statistics can help in setting a task's priorities |
|
relative to other tasks for cpu, io, rss limits etc. |
|
|
|
Say N if unsure. |
|
|
|
config TASK_XACCT |
|
bool "Enable extended accounting over taskstats" |
|
depends on TASKSTATS |
|
help |
|
Collect extended task accounting data and send the data |
|
to userland for processing over the taskstats interface. |
|
|
|
Say N if unsure. |
|
|
|
config TASK_IO_ACCOUNTING |
|
bool "Enable per-task storage I/O accounting" |
|
depends on TASK_XACCT |
|
help |
|
Collect information on the number of bytes of storage I/O which this |
|
task has caused. |
|
|
|
Say N if unsure. |
|
|
|
config PSI |
|
bool "Pressure stall information tracking" |
|
help |
|
Collect metrics that indicate how overcommitted the CPU, memory, |
|
and IO capacity are in the system. |
|
|
|
If you say Y here, the kernel will create /proc/pressure/ with the |
|
pressure statistics files cpu, memory, and io. These will indicate |
|
the share of walltime in which some or all tasks in the system are |
|
delayed due to contention of the respective resource. |
|
|
|
In kernels with cgroup support, cgroups (cgroup2 only) will |
|
have cpu.pressure, memory.pressure, and io.pressure files, |
|
which aggregate pressure stalls for the grouped tasks only. |
|
|
|
For more details see Documentation/accounting/psi.rst. |
|
|
|
Say N if unsure. |
|
|
|
config PSI_DEFAULT_DISABLED |
|
bool "Require boot parameter to enable pressure stall information tracking" |
|
default n |
|
depends on PSI |
|
help |
|
If set, pressure stall information tracking will be disabled |
|
per default but can be enabled through passing psi=1 on the |
|
kernel commandline during boot. |
|
|
|
This feature adds some code to the task wakeup and sleep |
|
paths of the scheduler. The overhead is too low to affect |
|
common scheduling-intense workloads in practice (such as |
|
webservers, memcache), but it does show up in artificial |
|
scheduler stress tests, such as hackbench. |
|
|
|
If you are paranoid and not sure what the kernel will be |
|
used for, say Y. |
|
|
|
Say N if unsure. |
|
|
|
endmenu # "CPU/Task time and stats accounting" |
|
|
|
config CPU_ISOLATION |
|
bool "CPU isolation" |
|
depends on SMP || COMPILE_TEST |
|
default y |
|
help |
|
Make sure that CPUs running critical tasks are not disturbed by |
|
any source of "noise" such as unbound workqueues, timers, kthreads... |
|
Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
|
the "isolcpus=" boot parameter. |
|
|
|
Say Y if unsure. |
|
|
|
source "kernel/rcu/Kconfig" |
|
|
|
config BUILD_BIN2C |
|
bool |
|
default n |
|
|
|
config IKCONFIG |
|
tristate "Kernel .config support" |
|
help |
|
This option enables the complete Linux kernel ".config" file |
|
contents to be saved in the kernel. It provides documentation |
|
of which kernel options are used in a running kernel or in an |
|
on-disk kernel. This information can be extracted from the kernel |
|
image file with the script scripts/extract-ikconfig and used as |
|
input to rebuild the current kernel or to build another kernel. |
|
It can also be extracted from a running kernel by reading |
|
/proc/config.gz if enabled (below). |
|
|
|
config IKCONFIG_PROC |
|
bool "Enable access to .config through /proc/config.gz" |
|
depends on IKCONFIG && PROC_FS |
|
help |
|
This option enables access to the kernel configuration file |
|
through /proc/config.gz. |
|
|
|
config IKHEADERS |
|
tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz" |
|
depends on SYSFS |
|
help |
|
This option enables access to the in-kernel headers that are generated during |
|
the build process. These can be used to build eBPF tracing programs, |
|
or similar programs. If you build the headers as a module, a module called |
|
kheaders.ko is built which can be loaded on-demand to get access to headers. |
|
|
|
config LOG_BUF_SHIFT |
|
int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" |
|
range 12 25 |
|
default 17 |
|
depends on PRINTK |
|
help |
|
Select the minimal kernel log buffer size as a power of 2. |
|
The final size is affected by LOG_CPU_MAX_BUF_SHIFT config |
|
parameter, see below. Any higher size also might be forced |
|
by "log_buf_len" boot parameter. |
|
|
|
Examples: |
|
17 => 128 KB |
|
16 => 64 KB |
|
15 => 32 KB |
|
14 => 16 KB |
|
13 => 8 KB |
|
12 => 4 KB |
|
|
|
config LOG_CPU_MAX_BUF_SHIFT |
|
int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" |
|
depends on SMP |
|
range 0 21 |
|
default 12 if !BASE_SMALL |
|
default 0 if BASE_SMALL |
|
depends on PRINTK |
|
help |
|
This option allows to increase the default ring buffer size |
|
according to the number of CPUs. The value defines the contribution |
|
of each CPU as a power of 2. The used space is typically only few |
|
lines however it might be much more when problems are reported, |
|
e.g. backtraces. |
|
|
|
The increased size means that a new buffer has to be allocated and |
|
the original static one is unused. It makes sense only on systems |
|
with more CPUs. Therefore this value is used only when the sum of |
|
contributions is greater than the half of the default kernel ring |
|
buffer as defined by LOG_BUF_SHIFT. The default values are set |
|
so that more than 16 CPUs are needed to trigger the allocation. |
|
|
|
Also this option is ignored when "log_buf_len" kernel parameter is |
|
used as it forces an exact (power of two) size of the ring buffer. |
|
|
|
The number of possible CPUs is used for this computation ignoring |
|
hotplugging making the computation optimal for the worst case |
|
scenario while allowing a simple algorithm to be used from bootup. |
|
|
|
Examples shift values and their meaning: |
|
17 => 128 KB for each CPU |
|
16 => 64 KB for each CPU |
|
15 => 32 KB for each CPU |
|
14 => 16 KB for each CPU |
|
13 => 8 KB for each CPU |
|
12 => 4 KB for each CPU |
|
|
|
config PRINTK_SAFE_LOG_BUF_SHIFT |
|
int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" |
|
range 10 21 |
|
default 13 |
|
depends on PRINTK |
|
help |
|
Select the size of an alternate printk per-CPU buffer where messages |
|
printed from usafe contexts are temporary stored. One example would |
|
be NMI messages, another one - printk recursion. The messages are |
|
copied to the main log buffer in a safe context to avoid a deadlock. |
|
The value defines the size as a power of 2. |
|
|
|
Those messages are rare and limited. The largest one is when |
|
a backtrace is printed. It usually fits into 4KB. Select |
|
8KB if you want to be on the safe side. |
|
|
|
Examples: |
|
17 => 128 KB for each CPU |
|
16 => 64 KB for each CPU |
|
15 => 32 KB for each CPU |
|
14 => 16 KB for each CPU |
|
13 => 8 KB for each CPU |
|
12 => 4 KB for each CPU |
|
|
|
config PRINTK_INDEX |
|
bool "Printk indexing debugfs interface" |
|
depends on PRINTK && DEBUG_FS |
|
help |
|
Add support for indexing of all printk formats known at compile time |
|
at <debugfs>/printk/index/<module>. |
|
|
|
This can be used as part of maintaining daemons which monitor |
|
/dev/kmsg, as it permits auditing the printk formats present in a |
|
kernel, allowing detection of cases where monitored printks are |
|
changed or no longer present. |
|
|
|
There is no additional runtime cost to printk with this enabled. |
|
|
|
# |
|
# Architectures with an unreliable sched_clock() should select this: |
|
# |
|
config HAVE_UNSTABLE_SCHED_CLOCK |
|
bool |
|
|
|
config GENERIC_SCHED_CLOCK |
|
bool |
|
|
|
menu "Scheduler features" |
|
|
|
config UCLAMP_TASK |
|
bool "Enable utilization clamping for RT/FAIR tasks" |
|
depends on CPU_FREQ_GOV_SCHEDUTIL |
|
help |
|
This feature enables the scheduler to track the clamped utilization |
|
of each CPU based on RUNNABLE tasks scheduled on that CPU. |
|
|
|
With this option, the user can specify the min and max CPU |
|
utilization allowed for RUNNABLE tasks. The max utilization defines |
|
the maximum frequency a task should use while the min utilization |
|
defines the minimum frequency it should use. |
|
|
|
Both min and max utilization clamp values are hints to the scheduler, |
|
aiming at improving its frequency selection policy, but they do not |
|
enforce or grant any specific bandwidth for tasks. |
|
|
|
If in doubt, say N. |
|
|
|
config UCLAMP_BUCKETS_COUNT |
|
int "Number of supported utilization clamp buckets" |
|
range 5 20 |
|
default 5 |
|
depends on UCLAMP_TASK |
|
help |
|
Defines the number of clamp buckets to use. The range of each bucket |
|
will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the |
|
number of clamp buckets the finer their granularity and the higher |
|
the precision of clamping aggregation and tracking at run-time. |
|
|
|
For example, with the minimum configuration value we will have 5 |
|
clamp buckets tracking 20% utilization each. A 25% boosted tasks will |
|
be refcounted in the [20..39]% bucket and will set the bucket clamp |
|
effective value to 25%. |
|
If a second 30% boosted task should be co-scheduled on the same CPU, |
|
that task will be refcounted in the same bucket of the first task and |
|
it will boost the bucket clamp effective value to 30%. |
|
The clamp effective value of a bucket is reset to its nominal value |
|
(20% in the example above) when there are no more tasks refcounted in |
|
that bucket. |
|
|
|
An additional boost/capping margin can be added to some tasks. In the |
|
example above the 25% task will be boosted to 30% until it exits the |
|
CPU. If that should be considered not acceptable on certain systems, |
|
it's always possible to reduce the margin by increasing the number of |
|
clamp buckets to trade off used memory for run-time tracking |
|
precision. |
|
|
|
If in doubt, use the default value. |
|
|
|
endmenu |
|
|
|
# |
|
# For architectures that want to enable the support for NUMA-affine scheduler |
|
# balancing logic: |
|
# |
|
config ARCH_SUPPORTS_NUMA_BALANCING |
|
bool |
|
|
|
# |
|
# For architectures that prefer to flush all TLBs after a number of pages |
|
# are unmapped instead of sending one IPI per page to flush. The architecture |
|
# must provide guarantees on what happens if a clean TLB cache entry is |
|
# written after the unmap. Details are in mm/rmap.c near the check for |
|
# should_defer_flush. The architecture should also consider if the full flush |
|
# and the refill costs are offset by the savings of sending fewer IPIs. |
|
config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH |
|
bool |
|
|
|
config CC_HAS_INT128 |
|
def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT |
|
|
|
config CC_IMPLICIT_FALLTHROUGH |
|
string |
|
default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) |
|
default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) |
|
|
|
# Currently, disable gcc-12 array-bounds globally. |
|
# We may want to target only particular configurations some day. |
|
config GCC12_NO_ARRAY_BOUNDS |
|
def_bool y |
|
|
|
config CC_NO_ARRAY_BOUNDS |
|
bool |
|
default y if CC_IS_GCC && GCC_VERSION >= 120000 && GCC_VERSION < 130000 && GCC12_NO_ARRAY_BOUNDS |
|
|
|
# |
|
# For architectures that know their GCC __int128 support is sound |
|
# |
|
config ARCH_SUPPORTS_INT128 |
|
bool |
|
|
|
# For architectures that (ab)use NUMA to represent different memory regions |
|
# all cpu-local but of different latencies, such as SuperH. |
|
# |
|
config ARCH_WANT_NUMA_VARIABLE_LOCALITY |
|
bool |
|
|
|
config NUMA_BALANCING |
|
bool "Memory placement aware NUMA scheduler" |
|
depends on ARCH_SUPPORTS_NUMA_BALANCING |
|
depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY |
|
depends on SMP && NUMA && MIGRATION && !PREEMPT_RT |
|
help |
|
This option adds support for automatic NUMA aware memory/task placement. |
|
The mechanism is quite primitive and is based on migrating memory when |
|
it has references to the node the task is running on. |
|
|
|
This system will be inactive on UMA systems. |
|
|
|
config NUMA_BALANCING_DEFAULT_ENABLED |
|
bool "Automatically enable NUMA aware memory/task placement" |
|
default y |
|
depends on NUMA_BALANCING |
|
help |
|
If set, automatic NUMA balancing will be enabled if running on a NUMA |
|
machine. |
|
|
|
menuconfig CGROUPS |
|
bool "Control Group support" |
|
select KERNFS |
|
help |
|
This option adds support for grouping sets of processes together, for |
|
use with process control subsystems such as Cpusets, CFS, memory |
|
controls or device isolation. |
|
See |
|
- Documentation/scheduler/sched-design-CFS.rst (CFS) |
|
- Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation |
|
and resource control) |
|
|
|
Say N if unsure. |
|
|
|
if CGROUPS |
|
|
|
config PAGE_COUNTER |
|
bool |
|
|
|
config CGROUP_FAVOR_DYNMODS |
|
bool "Favor dynamic modification latency reduction by default" |
|
help |
|
This option enables the "favordynmods" mount option by default |
|
which reduces the latencies of dynamic cgroup modifications such |
|
as task migrations and controller on/offs at the cost of making |
|
hot path operations such as forks and exits more expensive. |
|
|
|
Say N if unsure. |
|
|
|
config MEMCG |
|
bool "Memory controller" |
|
select PAGE_COUNTER |
|
select EVENTFD |
|
help |
|
Provides control over the memory footprint of tasks in a cgroup. |
|
|
|
config MEMCG_KMEM |
|
bool |
|
depends on MEMCG && !SLOB |
|
default y |
|
|
|
config BLK_CGROUP |
|
bool "IO controller" |
|
depends on BLOCK |
|
default n |
|
help |
|
Generic block IO controller cgroup interface. This is the common |
|
cgroup interface which should be used by various IO controlling |
|
policies. |
|
|
|
Currently, CFQ IO scheduler uses it to recognize task groups and |
|
control disk bandwidth allocation (proportional time slice allocation) |
|
to such task groups. It is also used by bio throttling logic in |
|
block layer to implement upper limit in IO rates on a device. |
|
|
|
This option only enables generic Block IO controller infrastructure. |
|
One needs to also enable actual IO controlling logic/policy. For |
|
enabling proportional weight division of disk bandwidth in CFQ, set |
|
CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set |
|
CONFIG_BLK_DEV_THROTTLING=y. |
|
|
|
See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information. |
|
|
|
config CGROUP_WRITEBACK |
|
bool |
|
depends on MEMCG && BLK_CGROUP |
|
default y |
|
|
|
menuconfig CGROUP_SCHED |
|
bool "CPU controller" |
|
default n |
|
help |
|
This feature lets CPU scheduler recognize task groups and control CPU |
|
bandwidth allocation to such task groups. It uses cgroups to group |
|
tasks. |
|
|
|
if CGROUP_SCHED |
|
config FAIR_GROUP_SCHED |
|
bool "Group scheduling for SCHED_OTHER" |
|
depends on CGROUP_SCHED |
|
default CGROUP_SCHED |
|
|
|
config CFS_BANDWIDTH |
|
bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" |
|
depends on FAIR_GROUP_SCHED |
|
default n |
|
help |
|
This option allows users to define CPU bandwidth rates (limits) for |
|
tasks running within the fair group scheduler. Groups with no limit |
|
set are considered to be unconstrained and will run with no |
|
restriction. |
|
See Documentation/scheduler/sched-bwc.rst for more information. |
|
|
|
config RT_GROUP_SCHED |
|
bool "Group scheduling for SCHED_RR/FIFO" |
|
depends on CGROUP_SCHED |
|
default n |
|
help |
|
This feature lets you explicitly allocate real CPU bandwidth |
|
to task groups. If enabled, it will also make it impossible to |
|
schedule realtime tasks for non-root users until you allocate |
|
realtime bandwidth for them. |
|
See Documentation/scheduler/sched-rt-group.rst for more information. |
|
|
|
endif #CGROUP_SCHED |
|
|
|
config UCLAMP_TASK_GROUP |
|
bool "Utilization clamping per group of tasks" |
|
depends on CGROUP_SCHED |
|
depends on UCLAMP_TASK |
|
default n |
|
help |
|
This feature enables the scheduler to track the clamped utilization |
|
of each CPU based on RUNNABLE tasks currently scheduled on that CPU. |
|
|
|
When this option is enabled, the user can specify a min and max |
|
CPU bandwidth which is allowed for each single task in a group. |
|
The max bandwidth allows to clamp the maximum frequency a task |
|
can use, while the min bandwidth allows to define a minimum |
|
frequency a task will always use. |
|
|
|
When task group based utilization clamping is enabled, an eventually |
|
specified task-specific clamp value is constrained by the cgroup |
|
specified clamp value. Both minimum and maximum task clamping cannot |
|
be bigger than the corresponding clamping defined at task group level. |
|
|
|
If in doubt, say N. |
|
|
|
config CGROUP_PIDS |
|
bool "PIDs controller" |
|
help |
|
Provides enforcement of process number limits in the scope of a |
|
cgroup. Any attempt to fork more processes than is allowed in the |
|
cgroup will fail. PIDs are fundamentally a global resource because it |
|
is fairly trivial to reach PID exhaustion before you reach even a |
|
conservative kmemcg limit. As a result, it is possible to grind a |
|
system to halt without being limited by other cgroup policies. The |
|
PIDs controller is designed to stop this from happening. |
|
|
|
It should be noted that organisational operations (such as attaching |
|
to a cgroup hierarchy) will *not* be blocked by the PIDs controller, |
|
since the PIDs limit only affects a process's ability to fork, not to |
|
attach to a cgroup. |
|
|
|
config CGROUP_RDMA |
|
bool "RDMA controller" |
|
help |
|
Provides enforcement of RDMA resources defined by IB stack. |
|
It is fairly easy for consumers to exhaust RDMA resources, which |
|
can result into resource unavailability to other consumers. |
|
RDMA controller is designed to stop this from happening. |
|
Attaching processes with active RDMA resources to the cgroup |
|
hierarchy is allowed even if can cross the hierarchy's limit. |
|
|
|
config CGROUP_FREEZER |
|
bool "Freezer controller" |
|
help |
|
Provides a way to freeze and unfreeze all tasks in a |
|
cgroup. |
|
|
|
This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
|
controller includes important in-kernel memory consumers per default. |
|
|
|
If you're using cgroup2, say N. |
|
|
|
config CGROUP_HUGETLB |
|
bool "HugeTLB controller" |
|
depends on HUGETLB_PAGE |
|
select PAGE_COUNTER |
|
default n |
|
help |
|
Provides a cgroup controller for HugeTLB pages. |
|
When you enable this, you can put a per cgroup limit on HugeTLB usage. |
|
The limit is enforced during page fault. Since HugeTLB doesn't |
|
support page reclaim, enforcing the limit at page fault time implies |
|
that, the application will get SIGBUS signal if it tries to access |
|
HugeTLB pages beyond its limit. This requires the application to know |
|
beforehand how much HugeTLB pages it would require for its use. The |
|
control group is tracked in the third page lru pointer. This means |
|
that we cannot use the controller with huge page less than 3 pages. |
|
|
|
config CPUSETS |
|
bool "Cpuset controller" |
|
depends on SMP |
|
help |
|
This option will let you create and manage CPUSETs which |
|
allow dynamically partitioning a system into sets of CPUs and |
|
Memory Nodes and assigning tasks to run only within those sets. |
|
This is primarily useful on large SMP or NUMA systems. |
|
|
|
Say N if unsure. |
|
|
|
config PROC_PID_CPUSET |
|
bool "Include legacy /proc/<pid>/cpuset file" |
|
depends on CPUSETS |
|
default y |
|
|
|
config CGROUP_DEVICE |
|
bool "Device controller" |
|
help |
|
Provides a cgroup controller implementing whitelists for |
|
devices which a process in the cgroup can mknod or open. |
|
|
|
config CGROUP_CPUACCT |
|
bool "Simple CPU accounting controller" |
|
help |
|
Provides a simple controller for monitoring the |
|
total CPU consumed by the tasks in a cgroup. |
|
|
|
config CGROUP_PERF |
|
bool "Perf controller" |
|
depends on PERF_EVENTS |
|
help |
|
This option extends the perf per-cpu mode to restrict monitoring |
|
to threads which belong to the cgroup specified and run on the |
|
designated cpu. Or this can be used to have cgroup ID in samples |
|
so that it can monitor performance events among cgroups. |
|
|
|
Say N if unsure. |
|
|
|
config CGROUP_BPF |
|
bool "Support for eBPF programs attached to cgroups" |
|
depends on BPF_SYSCALL |
|
select SOCK_CGROUP_DATA |
|
help |
|
Allow attaching eBPF programs to a cgroup using the bpf(2) |
|
syscall command BPF_PROG_ATTACH. |
|
|
|
In which context these programs are accessed depends on the type |
|
of attachment. For instance, programs that are attached using |
|
BPF_CGROUP_INET_INGRESS will be executed on the ingress path of |
|
inet sockets. |
|
|
|
config CGROUP_MISC |
|
bool "Misc resource controller" |
|
default n |
|
help |
|
Provides a controller for miscellaneous resources on a host. |
|
|
|
Miscellaneous scalar resources are the resources on the host system |
|
which cannot be abstracted like the other cgroups. This controller |
|
tracks and limits the miscellaneous resources used by a process |
|
attached to a cgroup hierarchy. |
|
|
|
For more information, please check misc cgroup section in |
|
/Documentation/admin-guide/cgroup-v2.rst. |
|
|
|
config CGROUP_DEBUG |
|
bool "Debug controller" |
|
default n |
|
depends on DEBUG_KERNEL |
|
help |
|
This option enables a simple controller that exports |
|
debugging information about the cgroups framework. This |
|
controller is for control cgroup debugging only. Its |
|
interfaces are not stable. |
|
|
|
Say N. |
|
|
|
config SOCK_CGROUP_DATA |
|
bool |
|
default n |
|
|
|
endif # CGROUPS |
|
|
|
menuconfig NAMESPACES |
|
bool "Namespaces support" if EXPERT |
|
depends on MULTIUSER |
|
default !EXPERT |
|
help |
|
Provides the way to make tasks work with different objects using |
|
the same id. For example same IPC id may refer to different objects |
|
or same user id or pid may refer to different tasks when used in |
|
different namespaces. |
|
|
|
if NAMESPACES |
|
|
|
config UTS_NS |
|
bool "UTS namespace" |
|
default y |
|
help |
|
In this namespace tasks see different info provided with the |
|
uname() system call |
|
|
|
config TIME_NS |
|
bool "TIME namespace" |
|
depends on GENERIC_VDSO_TIME_NS |
|
default y |
|
help |
|
In this namespace boottime and monotonic clocks can be set. |
|
The time will keep going with the same pace. |
|
|
|
config IPC_NS |
|
bool "IPC namespace" |
|
depends on (SYSVIPC || POSIX_MQUEUE) |
|
default y |
|
help |
|
In this namespace tasks work with IPC ids which correspond to |
|
different IPC objects in different namespaces. |
|
|
|
config USER_NS |
|
bool "User namespace" |
|
default n |
|
help |
|
This allows containers, i.e. vservers, to use user namespaces |
|
to provide different user info for different servers. |
|
|
|
When user namespaces are enabled in the kernel it is |
|
recommended that the MEMCG option also be enabled and that |
|
user-space use the memory control groups to limit the amount |
|
of memory a memory unprivileged users can use. |
|
|
|
If unsure, say N. |
|
|
|
config PID_NS |
|
bool "PID Namespaces" |
|
default y |
|
help |
|
Support process id namespaces. This allows having multiple |
|
processes with the same pid as long as they are in different |
|
pid namespaces. This is a building block of containers. |
|
|
|
config NET_NS |
|
bool "Network namespace" |
|
depends on NET |
|
default y |
|
help |
|
Allow user space to create what appear to be multiple instances |
|
of the network stack. |
|
|
|
endif # NAMESPACES |
|
|
|
config CHECKPOINT_RESTORE |
|
bool "Checkpoint/restore support" |
|
depends on PROC_FS |
|
select PROC_CHILDREN |
|
select KCMP |
|
default n |
|
help |
|
Enables additional kernel features in a sake of checkpoint/restore. |
|
In particular it adds auxiliary prctl codes to setup process text, |
|
data and heap segment sizes, and a few additional /proc filesystem |
|
entries. |
|
|
|
If unsure, say N here. |
|
|
|
config SCHED_AUTOGROUP |
|
bool "Automatic process group scheduling" |
|
select CGROUPS |
|
select CGROUP_SCHED |
|
select FAIR_GROUP_SCHED |
|
help |
|
This option optimizes the scheduler for common desktop workloads by |
|
automatically creating and populating task groups. This separation |
|
of workloads isolates aggressive CPU burners (like build jobs) from |
|
desktop applications. Task group autogeneration is currently based |
|
upon task session. |
|
|
|
config SYSFS_DEPRECATED |
|
bool "Enable deprecated sysfs features to support old userspace tools" |
|
depends on SYSFS |
|
default n |
|
help |
|
This option adds code that switches the layout of the "block" class |
|
devices, to not show up in /sys/class/block/, but only in |
|
/sys/block/. |
|
|
|
This switch is only active when the sysfs.deprecated=1 boot option is |
|
passed or the SYSFS_DEPRECATED_V2 option is set. |
|
|
|
This option allows new kernels to run on old distributions and tools, |
|
which might get confused by /sys/class/block/. Since 2007/2008 all |
|
major distributions and tools handle this just fine. |
|
|
|
Recent distributions and userspace tools after 2009/2010 depend on |
|
the existence of /sys/class/block/, and will not work with this |
|
option enabled. |
|
|
|
Only if you are using a new kernel on an old distribution, you might |
|
need to say Y here. |
|
|
|
config SYSFS_DEPRECATED_V2 |
|
bool "Enable deprecated sysfs features by default" |
|
default n |
|
depends on SYSFS |
|
depends on SYSFS_DEPRECATED |
|
help |
|
Enable deprecated sysfs by default. |
|
|
|
See the CONFIG_SYSFS_DEPRECATED option for more details about this |
|
option. |
|
|
|
Only if you are using a new kernel on an old distribution, you might |
|
need to say Y here. Even then, odds are you would not need it |
|
enabled, you can always pass the boot option if absolutely necessary. |
|
|
|
config RELAY |
|
bool "Kernel->user space relay support (formerly relayfs)" |
|
select IRQ_WORK |
|
help |
|
This option enables support for relay interface support in |
|
certain file systems (such as debugfs). |
|
It is designed to provide an efficient mechanism for tools and |
|
facilities to relay large amounts of data from kernel space to |
|
user space. |
|
|
|
If unsure, say N. |
|
|
|
config BLK_DEV_INITRD |
|
bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" |
|
help |
|
The initial RAM filesystem is a ramfs which is loaded by the |
|
boot loader (loadlin or lilo) and that is mounted as root |
|
before the normal boot procedure. It is typically used to |
|
load modules needed to mount the "real" root file system, |
|
etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
|
|
|
If RAM disk support (BLK_DEV_RAM) is also included, this |
|
also enables initial RAM disk (initrd) support and adds |
|
15 Kbytes (more on some other architectures) to the kernel size. |
|
|
|
If unsure say Y. |
|
|
|
if BLK_DEV_INITRD |
|
|
|
source "usr/Kconfig" |
|
|
|
endif |
|
|
|
config BOOT_CONFIG |
|
bool "Boot config support" |
|
select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED |
|
help |
|
Extra boot config allows system admin to pass a config file as |
|
complemental extension of kernel cmdline when booting. |
|
The boot config file must be attached at the end of initramfs |
|
with checksum, size and magic word. |
|
See <file:Documentation/admin-guide/bootconfig.rst> for details. |
|
|
|
If unsure, say Y. |
|
|
|
config BOOT_CONFIG_EMBED |
|
bool "Embed bootconfig file in the kernel" |
|
depends on BOOT_CONFIG |
|
help |
|
Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the |
|
kernel. Usually, the bootconfig file is loaded with the initrd |
|
image. But if the system doesn't support initrd, this option will |
|
help you by embedding a bootconfig file while building the kernel. |
|
|
|
If unsure, say N. |
|
|
|
config BOOT_CONFIG_EMBED_FILE |
|
string "Embedded bootconfig file path" |
|
depends on BOOT_CONFIG_EMBED |
|
help |
|
Specify a bootconfig file which will be embedded to the kernel. |
|
This bootconfig will be used if there is no initrd or no other |
|
bootconfig in the initrd. |
|
|
|
config INITRAMFS_PRESERVE_MTIME |
|
bool "Preserve cpio archive mtimes in initramfs" |
|
default y |
|
help |
|
Each entry in an initramfs cpio archive carries an mtime value. When |
|
enabled, extracted cpio items take this mtime, with directory mtime |
|
setting deferred until after creation of any child entries. |
|
|
|
If unsure, say Y. |
|
|
|
choice |
|
prompt "Compiler optimization level" |
|
default CC_OPTIMIZE_FOR_PERFORMANCE |
|
|
|
config CC_OPTIMIZE_FOR_PERFORMANCE |
|
bool "Optimize for performance (-O2)" |
|
help |
|
This is the default optimization level for the kernel, building |
|
with the "-O2" compiler flag for best performance and most |
|
helpful compile-time warnings. |
|
|
|
config CC_OPTIMIZE_FOR_SIZE |
|
bool "Optimize for size (-Os)" |
|
help |
|
Choosing this option will pass "-Os" to your compiler resulting |
|
in a smaller kernel. |
|
|
|
endchoice |
|
|
|
config HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
|
bool |
|
help |
|
This requires that the arch annotates or otherwise protects |
|
its external entry points from being discarded. Linker scripts |
|
must also merge .text.*, .data.*, and .bss.* correctly into |
|
output sections. Care must be taken not to pull in unrelated |
|
sections (e.g., '.text.init'). Typically '.' in section names |
|
is used to distinguish them from label names / C identifiers. |
|
|
|
config LD_DEAD_CODE_DATA_ELIMINATION |
|
bool "Dead code and data elimination (EXPERIMENTAL)" |
|
depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION |
|
depends on EXPERT |
|
depends on $(cc-option,-ffunction-sections -fdata-sections) |
|
depends on $(ld-option,--gc-sections) |
|
help |
|
Enable this if you want to do dead code and data elimination with |
|
the linker by compiling with -ffunction-sections -fdata-sections, |
|
and linking with --gc-sections. |
|
|
|
This can reduce on disk and in-memory size of the kernel |
|
code and static data, particularly for small configs and |
|
on small systems. This has the possibility of introducing |
|
silently broken kernel if the required annotations are not |
|
present. This option is not well tested yet, so use at your |
|
own risk. |
|
|
|
config LD_ORPHAN_WARN |
|
def_bool y |
|
depends on ARCH_WANT_LD_ORPHAN_WARN |
|
depends on $(ld-option,--orphan-handling=warn) |
|
|
|
config SYSCTL |
|
bool |
|
|
|
config HAVE_UID16 |
|
bool |
|
|
|
config SYSCTL_EXCEPTION_TRACE |
|
bool |
|
help |
|
Enable support for /proc/sys/debug/exception-trace. |
|
|
|
config SYSCTL_ARCH_UNALIGN_NO_WARN |
|
bool |
|
help |
|
Enable support for /proc/sys/kernel/ignore-unaligned-usertrap |
|
Allows arch to define/use @no_unaligned_warning to possibly warn |
|
about unaligned access emulation going on under the hood. |
|
|
|
config SYSCTL_ARCH_UNALIGN_ALLOW |
|
bool |
|
help |
|
Enable support for /proc/sys/kernel/unaligned-trap |
|
Allows arches to define/use @unaligned_enabled to runtime toggle |
|
the unaligned access emulation. |
|
see arch/parisc/kernel/unaligned.c for reference |
|
|
|
config HAVE_PCSPKR_PLATFORM |
|
bool |
|
|
|
# interpreter that classic socket filters depend on |
|
config BPF |
|
bool |
|
select CRYPTO_LIB_SHA1 |
|
|
|
menuconfig EXPERT |
|
bool "Configure standard kernel features (expert users)" |
|
# Unhide debug options, to make the on-by-default options visible |
|
select DEBUG_KERNEL |
|
help |
|
This option allows certain base kernel options and settings |
|
to be disabled or tweaked. This is for specialized |
|
environments which can tolerate a "non-standard" kernel. |
|
Only use this if you really know what you are doing. |
|
|
|
config UID16 |
|
bool "Enable 16-bit UID system calls" if EXPERT |
|
depends on HAVE_UID16 && MULTIUSER |
|
default y |
|
help |
|
This enables the legacy 16-bit UID syscall wrappers. |
|
|
|
config MULTIUSER |
|
bool "Multiple users, groups and capabilities support" if EXPERT |
|
default y |
|
help |
|
This option enables support for non-root users, groups and |
|
capabilities. |
|
|
|
If you say N here, all processes will run with UID 0, GID 0, and all |
|
possible capabilities. Saying N here also compiles out support for |
|
system calls related to UIDs, GIDs, and capabilities, such as setuid, |
|
setgid, and capset. |
|
|
|
If unsure, say Y here. |
|
|
|
config SGETMASK_SYSCALL |
|
bool "sgetmask/ssetmask syscalls support" if EXPERT |
|
def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
|
help |
|
sys_sgetmask and sys_ssetmask are obsolete system calls |
|
no longer supported in libc but still enabled by default in some |
|
architectures. |
|
|
|
If unsure, leave the default option here. |
|
|
|
config SYSFS_SYSCALL |
|
bool "Sysfs syscall support" if EXPERT |
|
default y |
|
help |
|
sys_sysfs is an obsolete system call no longer supported in libc. |
|
Note that disabling this option is more secure but might break |
|
compatibility with some systems. |
|
|
|
If unsure say Y here. |
|
|
|
config FHANDLE |
|
bool "open by fhandle syscalls" if EXPERT |
|
select EXPORTFS |
|
default y |
|
help |
|
If you say Y here, a user level program will be able to map |
|
file names to handle and then later use the handle for |
|
different file system operations. This is useful in implementing |
|
userspace file servers, which now track files using handles instead |
|
of names. The handle would remain the same even if file names |
|
get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) |
|
syscalls. |
|
|
|
config POSIX_TIMERS |
|
bool "Posix Clocks & timers" if EXPERT |
|
default y |
|
help |
|
This includes native support for POSIX timers to the kernel. |
|
Some embedded systems have no use for them and therefore they |
|
can be configured out to reduce the size of the kernel image. |
|
|
|
When this option is disabled, the following syscalls won't be |
|
available: timer_create, timer_gettime: timer_getoverrun, |
|
timer_settime, timer_delete, clock_adjtime, getitimer, |
|
setitimer, alarm. Furthermore, the clock_settime, clock_gettime, |
|
clock_getres and clock_nanosleep syscalls will be limited to |
|
CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. |
|
|
|
If unsure say y. |
|
|
|
config PRINTK |
|
default y |
|
bool "Enable support for printk" if EXPERT |
|
select IRQ_WORK |
|
help |
|
This option enables normal printk support. Removing it |
|
eliminates most of the message strings from the kernel image |
|
and makes the kernel more or less silent. As this makes it |
|
very difficult to diagnose system problems, saying N here is |
|
strongly discouraged. |
|
|
|
config BUG |
|
bool "BUG() support" if EXPERT |
|
default y |
|
help |
|
Disabling this option eliminates support for BUG and WARN, reducing |
|
the size of your kernel image and potentially quietly ignoring |
|
numerous fatal conditions. You should only consider disabling this |
|
option for embedded systems with no facilities for reporting errors. |
|
Just say Y. |
|
|
|
config ELF_CORE |
|
depends on COREDUMP |
|
default y |
|
bool "Enable ELF core dumps" if EXPERT |
|
help |
|
Enable support for generating core dumps. Disabling saves about 4k. |
|
|
|
|
|
config PCSPKR_PLATFORM |
|
bool "Enable PC-Speaker support" if EXPERT |
|
depends on HAVE_PCSPKR_PLATFORM |
|
select I8253_LOCK |
|
default y |
|
help |
|
This option allows to disable the internal PC-Speaker |
|
support, saving some memory. |
|
|
|
config BASE_FULL |
|
default y |
|
bool "Enable full-sized data structures for core" if EXPERT |
|
help |
|
Disabling this option reduces the size of miscellaneous core |
|
kernel data structures. This saves memory on small machines, |
|
but may reduce performance. |
|
|
|
config FUTEX |
|
bool "Enable futex support" if EXPERT |
|
depends on !(SPARC32 && SMP) |
|
default y |
|
imply RT_MUTEXES |
|
help |
|
Disabling this option will cause the kernel to be built without |
|
support for "fast userspace mutexes". The resulting kernel may not |
|
run glibc-based applications correctly. |
|
|
|
config FUTEX_PI |
|
bool |
|
depends on FUTEX && RT_MUTEXES |
|
default y |
|
|
|
config EPOLL |
|
bool "Enable eventpoll support" if EXPERT |
|
default y |
|
help |
|
Disabling this option will cause the kernel to be built without |
|
support for epoll family of system calls. |
|
|
|
config SIGNALFD |
|
bool "Enable signalfd() system call" if EXPERT |
|
default y |
|
help |
|
Enable the signalfd() system call that allows to receive signals |
|
on a file descriptor. |
|
|
|
If unsure, say Y. |
|
|
|
config TIMERFD |
|
bool "Enable timerfd() system call" if EXPERT |
|
default y |
|
help |
|
Enable the timerfd() system call that allows to receive timer |
|
events on a file descriptor. |
|
|
|
If unsure, say Y. |
|
|
|
config EVENTFD |
|
bool "Enable eventfd() system call" if EXPERT |
|
default y |
|
help |
|
Enable the eventfd() system call that allows to receive both |
|
kernel notification (ie. KAIO) or userspace notifications. |
|
|
|
If unsure, say Y. |
|
|
|
config SHMEM |
|
bool "Use full shmem filesystem" if EXPERT |
|
default y |
|
depends on MMU |
|
help |
|
The shmem is an internal filesystem used to manage shared memory. |
|
It is backed by swap and manages resource limits. It is also exported |
|
to userspace as tmpfs if TMPFS is enabled. Disabling this |
|
option replaces shmem and tmpfs with the much simpler ramfs code, |
|
which may be appropriate on small systems without swap. |
|
|
|
config AIO |
|
bool "Enable AIO support" if EXPERT |
|
default y |
|
help |
|
This option enables POSIX asynchronous I/O which may by used |
|
by some high performance threaded applications. Disabling |
|
this option saves about 7k. |
|
|
|
config IO_URING |
|
bool "Enable IO uring support" if EXPERT |
|
select IO_WQ |
|
default y |
|
help |
|
This option enables support for the io_uring interface, enabling |
|
applications to submit and complete IO through submission and |
|
completion rings that are shared between the kernel and application. |
|
|
|
config ADVISE_SYSCALLS |
|
bool "Enable madvise/fadvise syscalls" if EXPERT |
|
default y |
|
help |
|
This option enables the madvise and fadvise syscalls, used by |
|
applications to advise the kernel about their future memory or file |
|
usage, improving performance. If building an embedded system where no |
|
applications use these syscalls, you can disable this option to save |
|
space. |
|
|
|
config MEMBARRIER |
|
bool "Enable membarrier() system call" if EXPERT |
|
default y |
|
help |
|
Enable the membarrier() system call that allows issuing memory |
|
barriers across all running threads, which can be used to distribute |
|
the cost of user-space memory barriers asymmetrically by transforming |
|
pairs of memory barriers into pairs consisting of membarrier() and a |
|
compiler barrier. |
|
|
|
If unsure, say Y. |
|
|
|
config KALLSYMS |
|
bool "Load all symbols for debugging/ksymoops" if EXPERT |
|
default y |
|
help |
|
Say Y here to let the kernel print out symbolic crash information and |
|
symbolic stack backtraces. This increases the size of the kernel |
|
somewhat, as all symbols have to be loaded into the kernel image. |
|
|
|
config KALLSYMS_ALL |
|
bool "Include all symbols in kallsyms" |
|
depends on DEBUG_KERNEL && KALLSYMS |
|
help |
|
Normally kallsyms only contains the symbols of functions for nicer |
|
OOPS messages and backtraces (i.e., symbols from the text and inittext |
|
sections). This is sufficient for most cases. And only if you want to |
|
enable kernel live patching, or other less common use cases (e.g., |
|
when a debugger is used) all symbols are required (i.e., names of |
|
variables from the data sections, etc). |
|
|
|
This option makes sure that all symbols are loaded into the kernel |
|
image (i.e., symbols from all sections) in cost of increased kernel |
|
size (depending on the kernel configuration, it may be 300KiB or |
|
something like this). |
|
|
|
Say N unless you really need all symbols, or kernel live patching. |
|
|
|
config KALLSYMS_ABSOLUTE_PERCPU |
|
bool |
|
depends on KALLSYMS |
|
default X86_64 && SMP |
|
|
|
config KALLSYMS_BASE_RELATIVE |
|
bool |
|
depends on KALLSYMS |
|
default !IA64 |
|
help |
|
Instead of emitting them as absolute values in the native word size, |
|
emit the symbol references in the kallsyms table as 32-bit entries, |
|
each containing a relative value in the range [base, base + U32_MAX] |
|
or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either |
|
an absolute value in the range [0, S32_MAX] or a relative value in the |
|
range [base, base + S32_MAX], where base is the lowest relative symbol |
|
address encountered in the image. |
|
|
|
On 64-bit builds, this reduces the size of the address table by 50%, |
|
but more importantly, it results in entries whose values are build |
|
time constants, and no relocation pass is required at runtime to fix |
|
up the entries based on the runtime load address of the kernel. |
|
|
|
# end of the "standard kernel features (expert users)" menu |
|
|
|
# syscall, maps, verifier |
|
|
|
config ARCH_HAS_MEMBARRIER_CALLBACKS |
|
bool |
|
|
|
config ARCH_HAS_MEMBARRIER_SYNC_CORE |
|
bool |
|
|
|
config KCMP |
|
bool "Enable kcmp() system call" if EXPERT |
|
help |
|
Enable the kernel resource comparison system call. It provides |
|
user-space with the ability to compare two processes to see if they |
|
share a common resource, such as a file descriptor or even virtual |
|
memory space. |
|
|
|
If unsure, say N. |
|
|
|
config RSEQ |
|
bool "Enable rseq() system call" if EXPERT |
|
default y |
|
depends on HAVE_RSEQ |
|
select MEMBARRIER |
|
help |
|
Enable the restartable sequences system call. It provides a |
|
user-space cache for the current CPU number value, which |
|
speeds up getting the current CPU number from user-space, |
|
as well as an ABI to speed up user-space operations on |
|
per-CPU data. |
|
|
|
If unsure, say Y. |
|
|
|
config DEBUG_RSEQ |
|
default n |
|
bool "Enabled debugging of rseq() system call" if EXPERT |
|
depends on RSEQ && DEBUG_KERNEL |
|
help |
|
Enable extra debugging checks for the rseq system call. |
|
|
|
If unsure, say N. |
|
|
|
config EMBEDDED |
|
bool "Embedded system" |
|
select EXPERT |
|
help |
|
This option should be enabled if compiling the kernel for |
|
an embedded system so certain expert options are available |
|
for configuration. |
|
|
|
config HAVE_PERF_EVENTS |
|
bool |
|
help |
|
See tools/perf/design.txt for details. |
|
|
|
config GUEST_PERF_EVENTS |
|
bool |
|
depends on HAVE_PERF_EVENTS |
|
|
|
config PERF_USE_VMALLOC |
|
bool |
|
help |
|
See tools/perf/design.txt for details |
|
|
|
config PC104 |
|
bool "PC/104 support" if EXPERT |
|
help |
|
Expose PC/104 form factor device drivers and options available for |
|
selection and configuration. Enable this option if your target |
|
machine has a PC/104 bus. |
|
|
|
menu "Kernel Performance Events And Counters" |
|
|
|
config PERF_EVENTS |
|
bool "Kernel performance events and counters" |
|
default y if PROFILING |
|
depends on HAVE_PERF_EVENTS |
|
select IRQ_WORK |
|
select SRCU |
|
help |
|
Enable kernel support for various performance events provided |
|
by software and hardware. |
|
|
|
Software events are supported either built-in or via the |
|
use of generic tracepoints. |
|
|
|
Most modern CPUs support performance events via performance |
|
counter registers. These registers count the number of certain |
|
types of hw events: such as instructions executed, cachemisses |
|
suffered, or branches mis-predicted - without slowing down the |
|
kernel or applications. These registers can also trigger interrupts |
|
when a threshold number of events have passed - and can thus be |
|
used to profile the code that runs on that CPU. |
|
|
|
The Linux Performance Event subsystem provides an abstraction of |
|
these software and hardware event capabilities, available via a |
|
system call and used by the "perf" utility in tools/perf/. It |
|
provides per task and per CPU counters, and it provides event |
|
capabilities on top of those. |
|
|
|
Say Y if unsure. |
|
|
|
config DEBUG_PERF_USE_VMALLOC |
|
default n |
|
bool "Debug: use vmalloc to back perf mmap() buffers" |
|
depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
|
select PERF_USE_VMALLOC |
|
help |
|
Use vmalloc memory to back perf mmap() buffers. |
|
|
|
Mostly useful for debugging the vmalloc code on platforms |
|
that don't require it. |
|
|
|
Say N if unsure. |
|
|
|
endmenu |
|
|
|
config SYSTEM_DATA_VERIFICATION |
|
def_bool n |
|
select SYSTEM_TRUSTED_KEYRING |
|
select KEYS |
|
select CRYPTO |
|
select CRYPTO_RSA |
|
select ASYMMETRIC_KEY_TYPE |
|
select ASYMMETRIC_PUBLIC_KEY_SUBTYPE |
|
select ASN1 |
|
select OID_REGISTRY |
|
select X509_CERTIFICATE_PARSER |
|
select PKCS7_MESSAGE_PARSER |
|
help |
|
Provide PKCS#7 message verification using the contents of the system |
|
trusted keyring to provide public keys. This then can be used for |
|
module verification, kexec image verification and firmware blob |
|
verification. |
|
|
|
config PROFILING |
|
bool "Profiling support" |
|
help |
|
Say Y here to enable the extended profiling support mechanisms used |
|
by profilers. |
|
|
|
config RUST |
|
bool "Rust support" |
|
depends on HAVE_RUST |
|
depends on RUST_IS_AVAILABLE |
|
depends on !MODVERSIONS |
|
depends on !GCC_PLUGINS |
|
depends on !RANDSTRUCT |
|
depends on !DEBUG_INFO_BTF |
|
select CONSTRUCTORS |
|
help |
|
Enables Rust support in the kernel. |
|
|
|
This allows other Rust-related options, like drivers written in Rust, |
|
to be selected. |
|
|
|
It is also required to be able to load external kernel modules |
|
written in Rust. |
|
|
|
See Documentation/rust/ for more information. |
|
|
|
If unsure, say N. |
|
|
|
config RUSTC_VERSION_TEXT |
|
string |
|
depends on RUST |
|
default $(shell,command -v $(RUSTC) >/dev/null 2>&1 && $(RUSTC) --version || echo n) |
|
|
|
config BINDGEN_VERSION_TEXT |
|
string |
|
depends on RUST |
|
default $(shell,command -v $(BINDGEN) >/dev/null 2>&1 && $(BINDGEN) --version || echo n) |
|
|
|
# |
|
# Place an empty function call at each tracepoint site. Can be |
|
# dynamically changed for a probe function. |
|
# |
|
config TRACEPOINTS |
|
bool |
|
|
|
endmenu # General setup |
|
|
|
source "arch/Kconfig" |
|
|
|
config RT_MUTEXES |
|
bool |
|
default y if PREEMPT_RT |
|
|
|
config BASE_SMALL |
|
int |
|
default 0 if BASE_FULL |
|
default 1 if !BASE_FULL |
|
|
|
config MODULE_SIG_FORMAT |
|
def_bool n |
|
select SYSTEM_DATA_VERIFICATION |
|
|
|
source "kernel/module/Kconfig" |
|
|
|
config INIT_ALL_POSSIBLE |
|
bool |
|
help |
|
Back when each arch used to define their own cpu_online_mask and |
|
cpu_possible_mask, some of them chose to initialize cpu_possible_mask |
|
with all 1s, and others with all 0s. When they were centralised, |
|
it was better to provide this option than to break all the archs |
|
and have several arch maintainers pursuing me down dark alleys. |
|
|
|
source "block/Kconfig" |
|
|
|
config PREEMPT_NOTIFIERS |
|
bool |
|
|
|
config PADATA |
|
depends on SMP |
|
bool |
|
|
|
config ASN1 |
|
tristate |
|
help |
|
Build a simple ASN.1 grammar compiler that produces a bytecode output |
|
that can be interpreted by the ASN.1 stream decoder and used to |
|
inform it as to what tags are to be expected in a stream and what |
|
functions to call on what tags. |
|
|
|
source "kernel/Kconfig.locks" |
|
|
|
config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE |
|
bool |
|
|
|
config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE |
|
bool |
|
|
|
# It may be useful for an architecture to override the definitions of the |
|
# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
|
# and the COMPAT_ variants in <linux/compat.h>, in particular to use a |
|
# different calling convention for syscalls. They can also override the |
|
# macros for not-implemented syscalls in kernel/sys_ni.c and |
|
# kernel/time/posix-stubs.c. All these overrides need to be available in |
|
# <asm/syscall_wrapper.h>. |
|
config ARCH_HAS_SYSCALL_WRAPPER |
|
def_bool n
|
|
|