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