| 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 |