Re: [PATCH] Update Graphics Info Hob FrameBufferSize Based on UEFI Spec 2.0

["Michael D Kinney" <michael.d.kinney@intel.com>]

Hi Ashraf,

HOBs must never use UINTN or pointer fields.  HOBs must always be the same size no matter
what CPU or CPU mode the structure is compiler for.

This is also a non-backwards compatible change to a HOB structure.

For the case where the GraphicsOutputProtocol is build for X64 and uses this HOB as input,
the UINT32 value from the HOB can be cast to UINTN for the protocol.

Given that the cast is from UINT32 -> UINT32 for IA32 builds and UINT32->UINT64 for X64
builds, I do not see any case where there would be possible loss of data.  The cast would
always be to a type that is the same size or larger.

Can you please verify the compiler error you observed?

Thanks,

Mike

> -----Original Message-----
> From: S, Ashraf Ali <ashraf.ali.s@intel.com>
> Sent: Sunday, January 2, 2022 8:34 AM
> To: devel@edk2.groups.io
> Cc: S, Ashraf Ali <ashraf.ali.s@intel.com>; Chaganty, Rangasai V <rangasai.v.chaganty@intel.com>; Solanki, Digant H
> <digant.h.solanki@intel.com>; V, Sangeetha <sangeetha.v@intel.com>; Ni, Ray <ray.ni@intel.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>; Gao, Liming <gaoliming@byosoft.com.cn>; Liu, Zhiguang <zhiguang.liu@intel.com>
> Subject: [PATCH] Update Graphics Info Hob FrameBufferSize Based on UEFI Spec 2.0
> 
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=3793
> Basede on UEFI Spec 2.0 section 17.7.1 structure
> EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE say FrameBufferSize should be size of
> UINTN, in MdePkg\Include\Guid\GraphicsInfoHob.h
> EFI_PEI_GRAPHICS_INFO_HOB FrameBufferSize  is UINT32,
> 
> UefiPayloadPkg\GraphicsOutputDxe\GraphicsOutput.c
> MdeModulePkg\Universal\Console\GraphicsOutputDxe\GraphicsOutput.c
> 
> Private->GraphicsOutputMode.FrameBufferSize = \
> GraphicsInfo->FrameBufferSize;
> 
> UINT32 value is getting assigned to UINTN,
> in X64 build compiler will throw possible loss of data error.
> 
> so update the EFI_PEI_GRAPHICS_INFO_HOB  based on UEFI Spec 2.0
> 
> Signed-off-by: Ashraf Ali S <ashraf.ali.s@intel.com>
> Cc: Rangasai V Chaganty <rangasai.v.chaganty@intel.com>
> Cc: Digant H Solanki <digant.h.solanki@intel.com>
> Cc: Sangeetha V <sangeetha.v@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Zhiguang Liu <zhiguang.liu@intel.com>
> ---
>  MdePkg/Include/Guid/GraphicsInfoHob.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/MdePkg/Include/Guid/GraphicsInfoHob.h b/MdePkg/Include/Guid/GraphicsInfoHob.h
> index 237911e63a..92bd907f20 100644
> --- a/MdePkg/Include/Guid/GraphicsInfoHob.h
> +++ b/MdePkg/Include/Guid/GraphicsInfoHob.h
> @@ -26,7 +26,7 @@
> 
>  typedef struct {
>    EFI_PHYSICAL_ADDRESS                    FrameBufferBase;
> -  UINT32                                  FrameBufferSize;
> +  UINTN                                   FrameBufferSize;
>    EFI_GRAPHICS_OUTPUT_MODE_INFORMATION    GraphicsMode;
>  } EFI_PEI_GRAPHICS_INFO_HOB;
> 
> --
> 2.30.2.windows.1