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108 lines
3.6 KiB
108 lines
3.6 KiB
============================================= |
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Kernel initialisation parameters on ARM Linux |
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============================================= |
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The following document describes the kernel initialisation parameter |
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structure, otherwise known as 'struct param_struct' which is used |
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for most ARM Linux architectures. |
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This structure is used to pass initialisation parameters from the |
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kernel loader to the Linux kernel proper, and may be short lived |
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through the kernel initialisation process. As a general rule, it |
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should not be referenced outside of arch/arm/kernel/setup.c:setup_arch(). |
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There are a lot of parameters listed in there, and they are described |
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below: |
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page_size |
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This parameter must be set to the page size of the machine, and |
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will be checked by the kernel. |
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nr_pages |
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This is the total number of pages of memory in the system. If |
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the memory is banked, then this should contain the total number |
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of pages in the system. |
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If the system contains separate VRAM, this value should not |
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include this information. |
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ramdisk_size |
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This is now obsolete, and should not be used. |
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flags |
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Various kernel flags, including: |
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===== ======================== |
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bit 0 1 = mount root read only |
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bit 1 unused |
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bit 2 0 = load ramdisk |
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bit 3 0 = prompt for ramdisk |
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===== ======================== |
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rootdev |
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major/minor number pair of device to mount as the root filesystem. |
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video_num_cols / video_num_rows |
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These two together describe the character size of the dummy console, |
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or VGA console character size. They should not be used for any other |
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purpose. |
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It's generally a good idea to set these to be either standard VGA, or |
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the equivalent character size of your fbcon display. This then allows |
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all the bootup messages to be displayed correctly. |
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video_x / video_y |
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This describes the character position of cursor on VGA console, and |
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is otherwise unused. (should not be used for other console types, and |
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should not be used for other purposes). |
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memc_control_reg |
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MEMC chip control register for Acorn Archimedes and Acorn A5000 |
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based machines. May be used differently by different architectures. |
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sounddefault |
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Default sound setting on Acorn machines. May be used differently by |
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different architectures. |
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adfsdrives |
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Number of ADFS/MFM disks. May be used differently by different |
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architectures. |
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bytes_per_char_h / bytes_per_char_v |
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These are now obsolete, and should not be used. |
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pages_in_bank[4] |
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Number of pages in each bank of the systems memory (used for RiscPC). |
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This is intended to be used on systems where the physical memory |
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is non-contiguous from the processors point of view. |
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pages_in_vram |
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Number of pages in VRAM (used on Acorn RiscPC). This value may also |
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be used by loaders if the size of the video RAM can't be obtained |
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from the hardware. |
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initrd_start / initrd_size |
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This describes the kernel virtual start address and size of the |
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initial ramdisk. |
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rd_start |
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Start address in sectors of the ramdisk image on a floppy disk. |
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system_rev |
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system revision number. |
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system_serial_low / system_serial_high |
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system 64-bit serial number |
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mem_fclk_21285 |
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The speed of the external oscillator to the 21285 (footbridge), |
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which control's the speed of the memory bus, timer & serial port. |
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Depending upon the speed of the cpu its value can be between |
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0-66 MHz. If no params are passed or a value of zero is passed, |
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then a value of 50 Mhz is the default on 21285 architectures. |
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paths[8][128] |
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These are now obsolete, and should not be used. |
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commandline |
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Kernel command line parameters. Details can be found elsewhere.
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