Hi,
On Wed, Nov 09, 2022 at 06:27:50PM +0100, Ard Biesheuvel wrote:
> For debugging purposes, allow the runtime override mask to be set from a
> EFI variable if one exists. For instance, the RT supported mask can be
> set to 0xfffd to disable the SetTime() runtime service, and enable all
> others:
>
> echo -ne "\x7\0\0\0\xfd\xff" \
> > /sys/firmware/efi/efivars/LinuxRtMaskOverride-eb66918a-7eef-402a-842e-931d21c38ae9
I'm really sorry, I applied this patch, but I couldn't find the file
(LinuxRtMaskOverride*) under efivars, and couldn't find another way of
setting the variable.
Thanks,
Alex
>
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> ---
> drivers/firmware/efi/efi.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index a46df5d1d0942751..faed1ef78c044924 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -367,7 +367,17 @@ static int __init efisubsys_init(void)
> }
> }
>
> - if (efi_rt_services_supported(EFI_RT_SUPPORTED_TIME_SERVICES))
> + if (efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) {
> + unsigned long size = sizeof(efi.runtime_supported_mask);
> +
> + if (efi.get_variable(L"LinuxRtMaskOverride",
> + &EFI_RT_PROPERTIES_TABLE_GUID, NULL, &size,
> + &efi.runtime_supported_mask) == EFI_SUCCESS)
> + pr_info("Overriding runtime_supported_mask to 0x%x\n",
> + efi.runtime_supported_mask);
> + }
> +
> + if (efi_rt_services_supported(EFI_RT_SUPPORTED_GET_TIME))
> platform_device_register_simple("rtc-efi", 0, NULL, 0);
>
> /* We register the efi directory at /sys/firmware/efi */
> --
> 2.35.1
>
