| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 1 | |
| 2 | efivarfs - a (U)EFI variable filesystem |
| 3 | |
| 4 | The efivarfs filesystem was created to address the shortcomings of |
| 5 | using entries in sysfs to maintain EFI variables. The old sysfs EFI |
| 6 | variables code only supported variables of up to 1024 bytes. This |
| 7 | limitation existed in version 0.99 of the EFI specification, but was |
| 8 | removed before any full releases. Since variables can now be larger |
| 9 | than a single page, sysfs isn't the best interface for this. |
| 10 | |
| 11 | Variables can be created, deleted and modified with the efivarfs |
| 12 | filesystem. |
| 13 | |
| 14 | efivarfs is typically mounted like this, |
| 15 | |
| 16 | mount -t efivarfs none /sys/firmware/efi/efivars |
| 17 | |
| 18 | Due to the presence of numerous firmware bugs where removing non-standard |
| 19 | UEFI variables causes the system firmware to fail to POST, efivarfs |
| 20 | files that are not well-known standardized variables are created |
| 21 | as immutable files. This doesn't prevent removal - "chattr -i" will work - |
| 22 | but it does prevent this kind of failure from being accomplished |
| 23 | accidentally. |