Re: [RFC PATCH v1 3/8] OvmfPkg/OvmfPkg.dec: Add 8259-related PCDs in OVMF DEC file

[Laszlo Ersek <lersek@redhat.com>]

On 04/03/19 09:00, Hao Wu wrote:
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1496
> 
> According to the DEC file in PcAtChipsetPkg, this commit adds the two
> 8259-driver-related PCDs into the OvmfPkg DEC file.
> 
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: David Woodhouse <dwmw2@infradead.org>
> Cc: Ray Ni <ray.ni@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> ---
>  OvmfPkg/OvmfPkg.dec | 26 ++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
> index fb89ebf3ad..cb838422aa 100644
> --- a/OvmfPkg/OvmfPkg.dec
> +++ b/OvmfPkg/OvmfPkg.dec
> @@ -128,6 +128,32 @@
>    gUefiOvmfPkgTokenSpaceGuid.PcdGuidedExtractHandlerTableSize|0x0|UINT32|0x1a
>    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfDecompressionScratchEnd|0x0|UINT32|0x1f
>  
> +  ## Pcd8259LegacyModeMask defines the default mask value for platform. This
> +  #  value is determined.
> +  #  1) If platform only support pure UEFI, value should be set to 0xFFFF or
> +  #     0xFFFE; Because only clock interrupt is allowed in legacy mode in pure
> +  #     UEFI platform.
> +  #  2) If platform install CSM and use thunk module:
> +  #     a) If thunk call provided by CSM binary requires some legacy interrupt
> +  #        support, the corresponding bit should be opened as 0.
> +  #        For example, if keyboard interfaces provided CSM binary use legacy
> +  #        keyboard interrupt in 8259 bit 1, then the value should be set to
> +  #        0xFFFC.
> +  #     b) If all thunk call provied by CSM binary do not require legacy
> +  #        interrupt support, value should be set to 0xFFFF or 0xFFFE.
> +  #
> +  #  The default value of legacy mode mask could be changed by
> +  #  EFI_LEGACY_8259_PROTOCOL->SetMask(). But it is rarely need change it
> +  #  except some special cases such as when initializing the CSM binary, it
> +  #  should be set to 0xFFFF to mask all legacy interrupt. Please restore the
> +  #  original legacy mask value if changing is made for these special case.
> +  gUefiOvmfPkgTokenSpaceGuid.Pcd8259LegacyModeMask|0xFFFF|UINT16|0x28
> +
> +  ## Pcd8259LegacyModeEdgeLevel defines the default edge level for legacy
> +  #  mode's interrrupt controller.
> +  #  For the corresponding bits, 0 = Edge triggered and 1 = Level triggered.
> +  gUefiOvmfPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel|0x0000|UINT16|0x29
> +
>  [PcdsDynamic, PcdsDynamicEx]
>    gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent|0|UINT64|2
>    gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashVariablesEnable|FALSE|BOOLEAN|0x10
> 

Thank you for wrapping the comments so nicely!


(1) In PcAtChipsetPkg.dec, both PCDs are declared under:

[PcdsFixedAtBuild, PcdsDynamic, PcdsDynamicEx, PcdsPatchableInModule]

but in OvmfPkg, this patch introduces both PCDs under just

[PcdsFixedAtBuild]

I think that's fine for now, but please mention this change in the
commit message.


(2) OVMF's PCD token space seems to have some holes, namely at: 3
decimal, 5 decimal, and 0x17.

Can you introduce the new PCDs with tokens 3 and 5, just to decrease the
fragmentation?


With (1) and (2) addressed:

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thanks,
Laszlo