Re: [PATCH v2 11/13] ArmPlatformPkg: Reserving framebuffer at build

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 22 December 2017 at 18:34,  <evan.lloyd@arm.com> wrote:
> From: Girish Pathak <girish.pathak at arm.com>
>
> Currently framebuffer memory is either reserved in special VRAM or
> dynamically allocated using boot services memory allocation functions.
> When allocated using boot services calls the memory has to be allocated
> as EfiBootServicesData. Unfortunately failures have been seen with this
> case.  There is also an unfortunate lack of control on the placement of
> the framebuffer.
>
> This change introduces two PCDs, PcdArmLcdFrameBufferBase and
> PcdArmLcdFrameBufferSize which enable build time reservation of the
> framebuffer, avoiding the need to allocate dynamically. This allows
> the framebuffer to appear as "I/O memory" outside of the normal RAM
> map, which is similar to the "VRAM" case.
>
> This change has no impact on current code, only enables the option
> of build time reservation of framebuffers.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Girish Pathak <girish.pathak@arm.com>
> Signed-off-by: Evan Lloyd <evan.lloyd@arm.com>
> ---
>  ArmPlatformPkg/ArmPlatformPkg.dec | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/ArmPlatformPkg/ArmPlatformPkg.dec b/ArmPlatformPkg/ArmPlatformPkg.dec
> index 9a61e4a511024c80e787500de5038779363f0d95..a887ffcfd9f3b168bfb19ff0a84e310c7891b527 100644
> --- a/ArmPlatformPkg/ArmPlatformPkg.dec
> +++ b/ArmPlatformPkg/ArmPlatformPkg.dec
> @@ -93,6 +93,10 @@ [PcdsFixedAtBuild.common]
>    gArmPlatformTokenSpaceGuid.PcdPL111LcdBase|0x0|UINT32|0x00000026
>    gArmPlatformTokenSpaceGuid.PcdArmHdLcdBase|0x0|UINT32|0x00000027
>
> +  ## If set, frame buffer memory will be reserved and mapped in the system RAM
> +  gArmPlatformTokenSpaceGuid.PcdArmLcdDdrFrameBufferSize|0x0|UINT32|0x00000043
> +  gArmPlatformTokenSpaceGuid.PcdArmLcdDdrFrameBufferBase|0x0|UINT64|0x00000044
> +

If these are only used in the VExpress edk2-platforms code, could you
please move them there instead? Thanks.

>    ## PL180 MCI
>    gArmPlatformTokenSpaceGuid.PcdPL180SysMciRegAddress|0x00000000|UINT32|0x00000028
>    gArmPlatformTokenSpaceGuid.PcdPL180MciBaseAddress|0x00000000|UINT32|0x00000029
> --
> Guid("CE165669-3EF3-493F-B85D-6190EE5B9759")
>