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36 lines
1.3 KiB
36 lines
1.3 KiB
What: /sys/firmware/efi/runtime-map/ |
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Date: December 2013 |
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Contact: Dave Young <[email protected]> |
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Description: Switching efi runtime services to virtual mode requires |
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that all efi memory ranges which have the runtime attribute |
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bit set to be mapped to virtual addresses. |
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The efi runtime services can only be switched to virtual |
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mode once without rebooting. The kexec kernel must maintain |
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the same physical to virtual address mappings as the first |
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kernel. The mappings are exported to sysfs so userspace tools |
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can reassemble them and pass them into the kexec kernel. |
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/sys/firmware/efi/runtime-map/ is the directory the kernel |
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exports that information in. |
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subdirectories are named with the number of the memory range:: |
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/sys/firmware/efi/runtime-map/0 |
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/sys/firmware/efi/runtime-map/1 |
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/sys/firmware/efi/runtime-map/2 |
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/sys/firmware/efi/runtime-map/3 |
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... |
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Each subdirectory contains five files: |
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========= ========================================= |
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attribute The attributes of the memory range. |
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num_pages The size of the memory range in pages. |
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phys_addr The physical address of the memory range. |
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type The type of the memory range. |
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virt_addr The virtual address of the memory range. |
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========= ========================================= |
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Above values are all hexadecimal numbers with the '0x' prefix. |
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Users: Kexec
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