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Diffstat (limited to 'Documentation/filesystems/efivarfs.rst')
| -rw-r--r-- | Documentation/filesystems/efivarfs.rst | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/filesystems/efivarfs.rst b/Documentation/filesystems/efivarfs.rst index 90ac65683e7e..0551985821b8 100644 --- a/Documentation/filesystems/efivarfs.rst +++ b/Documentation/filesystems/efivarfs.rst @@ -24,3 +24,20 @@ files that are not well-known standardized variables are created as immutable files. This doesn't prevent removal - "chattr -i" will work - but it does prevent this kind of failure from being accomplished accidentally. + +.. warning :: + When a content of an UEFI variable in /sys/firmware/efi/efivars is + displayed, for example using "hexdump", pay attention that the first + 4 bytes of the output represent the UEFI variable attributes, + in little-endian format. + + Practically the output of each efivar is composed of: + + +-----------------------------------+ + |4_bytes_of_attributes + efivar_data| + +-----------------------------------+ + +*See also:* + +- Documentation/admin-guide/acpi/ssdt-overlays.rst +- Documentation/ABI/stable/sysfs-firmware-efi-vars |