Based on kernel version 4.9. Page generated on 2016-12-21 14:27 EST.
1 What: /sys/firmware/efi/runtime-map/ 2 Date: December 2013 3 Contact: Dave Young <firstname.lastname@example.org> 4 Description: Switching efi runtime services to virtual mode requires 5 that all efi memory ranges which have the runtime attribute 6 bit set to be mapped to virtual addresses. 7 8 The efi runtime services can only be switched to virtual 9 mode once without rebooting. The kexec kernel must maintain 10 the same physical to virtual address mappings as the first 11 kernel. The mappings are exported to sysfs so userspace tools 12 can reassemble them and pass them into the kexec kernel. 13 14 /sys/firmware/efi/runtime-map/ is the directory the kernel 15 exports that information in. 16 17 subdirectories are named with the number of the memory range: 18 19 /sys/firmware/efi/runtime-map/0 20 /sys/firmware/efi/runtime-map/1 21 /sys/firmware/efi/runtime-map/2 22 /sys/firmware/efi/runtime-map/3 23 ... 24 25 Each subdirectory contains five files: 26 27 attribute : The attributes of the memory range. 28 num_pages : The size of the memory range in pages. 29 phys_addr : The physical address of the memory range. 30 type : The type of the memory range. 31 virt_addr : The virtual address of the memory range. 32 33 Above values are all hexadecimal numbers with the '0x' prefix. 34 Users: Kexec