Re: [edk2-platform PATCH v1 1/1] Platform/RaspberryPi: Make SetVariable return EFI_UNSUPPORTED at runtime

["Ard Biesheuvel" <ardb@kernel.org>]

On Fri, 23 Jul 2021 at 11:15, Sunny Wang <Sunny.Wang@arm.com> wrote:
>
> The RPi does not support storing UEFI NV variables at runtime. For now,
> gRT->SetVariable at runtime returns EFI_OUT_OF_RESOURCES which is not a
> proper error and would cause FWTS failures. Therefore, this patch is
> to make gRT->SetVariable at runtime return EFI_UNSUPPORTED.
>
> For more information, please check the issues below:
>    -https://github.com/pftf/RPi4/issues/6
>    -https://github.com/pftf/RPi4/issues/93
>    -https://github.com/pftf/RPi4/issues/163
>
> I also tested this with the ACS 3.0 FWTS. All the failures
> reported in issue 93 and 163 can be fixed by this patch.
>
> Cc: Samer El-Haj-Mahmoud <samer.el-haj-mahmoud@arm.com>
> Cc: Sami Mujawar <sami.mujawar@arm.com>
> Cc: Jeremy Linton <jeremy.linton@arm.com>
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Pete Batard <pete@akeo.ie>
> Cc: Leif Lindholm <leif@nuviainc.com>
>
> Signed-off-by: Sunny Wang <sunny.wang@arm.com>

This looks ok to me, but we should also expose this fact via the
EFI_RT_PROPERTIES_TABLE, so that the OS can anticipate this result.

> ---
>  .../Drivers/VarBlockServiceDxe/VarBlockService.c     | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/Platform/RaspberryPi/Drivers/VarBlockServiceDxe/VarBlockService.c b/Platform/RaspberryPi/Drivers/VarBlockServiceDxe/VarBlockService.c
> index 572309439a..16d4d4f178 100644
> --- a/Platform/RaspberryPi/Drivers/VarBlockServiceDxe/VarBlockService.c
> +++ b/Platform/RaspberryPi/Drivers/VarBlockServiceDxe/VarBlockService.c
> @@ -2,6 +2,7 @@
>   *
>   *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
>   *  Copyright (c) 2006-2014, Intel Corporation. All rights reserved.
> + *  Copyright (c) 2021, ARM Limited. All rights reserved.
>   *
>   *  SPDX-License-Identifier: BSD-2-Clause-Patent
>   *
> @@ -596,6 +597,7 @@ FvbProtocolWrite (
>      EFI_DEVICE_ERROR      - The block device is not functioning correctly and
>                              could not be written
>      EFI_INVALID_PARAMETER - NumBytes or Buffer are NULL
> +    EFI_UNSUPPORTED         This function is not supported at runtime
>
>  --*/
>  {
> @@ -605,6 +607,16 @@ FvbProtocolWrite (
>    EFI_STATUS Status;
>    EFI_STATUS ReturnStatus;
>
> +  //
> +  // The current variables support relies on modifying RPI_EFI.FD on SD
> +  // card, which works fine at boot time. However, at runtime, the SD
> +  // controller is exposed via ACPI and subsequently owned by the OS.
> +  // Therefore, we need to direclty return EFI_UNSUPPORTED.
> +  //
> +  if (EfiAtRuntime ()) {
> +   return EFI_UNSUPPORTED;
> +  }
> +
>    //
>    // Check for invalid conditions.
>    //
> --
> 2.31.0.windows.1
>