What: /sys/firmware/efi/runtime-map/
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Date: December 2013
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Contact: Dave Young <dyoung@redhat.com>
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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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