On Wed, 19 Aug 2020 at 11:28, Lee, Chun-Yi <joeyli.kernel@xxxxxxxxx> wrote:
>
> The efivars filesystem depends on GetVariable or GetNextVariable EFI
> runtime services. So the /sys/firmware/efi/efivars does not need to be
> created when GetVariable and GetNextVariable are not available.
>
> It is useful for userland to determine the availability of efivars
> filesystem.
>
> Cc: Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx>
> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
> Signed-off-by: "Lee, Chun-Yi" <jlee@xxxxxxxx>
Hello Joey,
This is not the right check to perform here: the efivarfs code could
be instantiated using a different efivars abstraction, so whether the
RT services are implemented is not entirely relevant.
Please look at commit f88814cc2578c121e6edef686365036db72af0ed
("efi/efivars: Expose RT service availability via efivars
abstraction") for an explanation of the underlying issue, and update
your patch accordingly.
> ---
> drivers/firmware/efi/efi.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index fdd1db025dbf..929fbf4dfd5d 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -404,11 +404,14 @@ static int __init efisubsys_init(void)
> if (error)
> goto err_remove_group;
>
> - /* and the standard mountpoint for efivarfs */
> - error = sysfs_create_mount_point(efi_kobj, "efivars");
> - if (error) {
> - pr_err("efivars: Subsystem registration failed.\n");
> - goto err_remove_group;
> + if (efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE |
> + EFI_RT_SUPPORTED_GET_NEXT_VARIABLE_NAME)) {
> + /* and the standard mountpoint for efivarfs */
> + error = sysfs_create_mount_point(efi_kobj, "efivars");
> + if (error) {
> + pr_err("efivars: Subsystem registration failed.\n");
> + goto err_remove_group;
> + }
> }
>
> if (efi_enabled(EFI_DBG) && efi_enabled(EFI_PRESERVE_BS_REGIONS))
> --
> 2.16.4
>
