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