Single EFI fix for v5.9-rc:
- ensure that the EFI bootloader control module only probes successfully
on systems that support the EFI SetVariable runtime service
efi: efibc: check for efivars write capability
Branden reports that commit
f88814cc2578c1 ("efi/efivars: Expose RT service availability via efivars abstraction")
regresses UEFI platforms that implement GetVariable but not SetVariable
when booting kernels that have EFIBC (bootloader control) enabled.
The reason is that EFIBC is a user of the efivars abstraction, which was
updated to permit users that rely only on the read capability, but not on
the write capability. EFIBC is in the latter category, so it has to check
explicitly whether efivars supports writes.
Fixes: f88814cc2578c1 ("efi/efivars: Expose RT service availability via efivars abstraction")
Tested-by: Branden Sherrell <sherrellbc@gmail.com>
Link: https://lore.kernel.org/linux-efi/AE217103-C96F-4AFC-8417-83EC11962004@gmail.com/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
1 file changed
