0001 What: /sys/firmware/efi/runtime-map/
0002 Date: December 2013
0003 Contact: Dave Young <dyoung@redhat.com>
0004 Description: Switching efi runtime services to virtual mode requires
0005 that all efi memory ranges which have the runtime attribute
0006 bit set to be mapped to virtual addresses.
0007
0008 The efi runtime services can only be switched to virtual
0009 mode once without rebooting. The kexec kernel must maintain
0010 the same physical to virtual address mappings as the first
0011 kernel. The mappings are exported to sysfs so userspace tools
0012 can reassemble them and pass them into the kexec kernel.
0013
0014 /sys/firmware/efi/runtime-map/ is the directory the kernel
0015 exports that information in.
0016
0017 subdirectories are named with the number of the memory range::
0018
0019 /sys/firmware/efi/runtime-map/0
0020 /sys/firmware/efi/runtime-map/1
0021 /sys/firmware/efi/runtime-map/2
0022 /sys/firmware/efi/runtime-map/3
0023 ...
0024
0025 Each subdirectory contains five files:
0026
0027 ========= =========================================
0028 attribute The attributes of the memory range.
0029 num_pages The size of the memory range in pages.
0030 phys_addr The physical address of the memory range.
0031 type The type of the memory range.
0032 virt_addr The virtual address of the memory range.
0033 ========= =========================================
0034
0035 Above values are all hexadecimal numbers with the '0x' prefix.
0036 Users: Kexec
