Re: [edk2-devel] [PATCH v2 15/30] EmbeddedPkg: Add PcdPrePiCpuIoSize width for LOONGARCH64

["Pedro Falcato" <pedro.falcato@gmail.com>]

On Wed, Nov 15, 2023 at 6:55 PM Leif Lindholm <quic_llindhol@quicinc.com> wrote:
>
> On 2023-11-06 03:29, Chao Li wrote:
> > Added LoongArch64 architecture CPU IO width.
> >
> > https://bugzilla.tianocore.org/show_bug.cgi?id=4584
> >
> > Cc: Leif Lindholm <quic_llindhol@quicinc.com>
> > Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> > Cc: Abner Chang <abner.chang@amd.com>
> > Cc: Daniel Schaefer <git@danielschaefer.me>
> > Signed-off-by: Chao Li <lichao@loongson.cn>
>
> Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
>
> I note that as a result of this we are now definining this token
> individually for 5 different architectures, in order to provide two
> different default values. We should probably look at consolidating
> those, but that responsibility doesn't have to land on this set.
>
> /
>      Leif
>
> > ---
> >   EmbeddedPkg/EmbeddedPkg.dec | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/EmbeddedPkg/EmbeddedPkg.dec b/EmbeddedPkg/EmbeddedPkg.dec
> > index 341ef5e6a6..241d4f3acc 100644
> > --- a/EmbeddedPkg/EmbeddedPkg.dec
> > +++ b/EmbeddedPkg/EmbeddedPkg.dec
> > @@ -165,6 +165,9 @@
> >   [PcdsFixedAtBuild.X64]
> >     gEmbeddedTokenSpaceGuid.PcdPrePiCpuIoSize|16|UINT8|0x00000011
> >
> > +[PcdsFixedAtBuild.LOONGARCH64]
> > +  gEmbeddedTokenSpaceGuid.PcdPrePiCpuIoSize|16|UINT8|0x00000011
> > +

Leif,

Can you clarify the meaning of PcdPrePiCpuIoSize? I was thinking it's
supposed to be the size of the port-mapped IO for the
architecture/platform (as hinted by in X64 = IA32 = 16, and ARM=0),
but from a quick git grep I can tell that
1) most platforms define it to something else (ArmVirt defines it to
16, real platforms have a plethora of other values)
2) gEmbeddedTokenSpaceGuid.PcdPrePiCpuIoSize has no internal consumer
in EmbeddedPkg, but only in ArmPlatformPkg and LoongArchQemuPkg (and
BeagleBoardPkg's PrePi)
3) Platform/Loongson/LoongArchQemuPkg/Loongson.dec:
gEmbeddedTokenSpaceGuid.PcdPrePiCpuIoSize|0|UINT8|0x00010001 <-- ??

and FWIW, LoongArch does not seem to have port-mapped IO at all.

-- 
Pedro


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