That makes sense, Andrew. Thanks for the info.
Regards,
Rohit
> Rohit,
>
> FYI I seem to remember when we added the bitfield verbiage to the UEFI Spec
> it was because there was lots of platform code that was using it. We did not
> really want to encourage its use it in public interfaces.
>
> Given there is lots of code 1st kind of things going on I’d figured I’d
> mention this.
>
> Thanks,
>
> Andrew Fish
>
>
> On Aug 23, 2022, at 2:28 PM, Rohit Mathew <rohit.mat...@arm.com> wrote:
> >
> > Hi Andrew,
> >
> > From: Andrew Fish <af...@apple.com>
> > Sent: 23 August 2022 21:11
> > To: devel@edk2.groups.io; Rohit Mathew <rohit.mat...@arm.com>
> > Cc: usern...@nvidia.com; Sami Mujawar <sami.muja...@arm.com> ; Alexei
> > Fedorov <alexei.fedo...@arm.com> ; Mike Kinney <michael.d.kin...@intel.com>
> > ; gaolim...@byosoft.com.cn; zhiguang....@intel.com; Swatisri Kantamsetti
> > <swatis...@nvidia.com> ; Thomas Abraham <thomas.abra...@arm.com> ; Thanu
> > Rangarajan <thanu.rangara...@arm.com> ; nd <n...@arm.com>
> > Subject: Re: [edk2-devel] [PATCH 1/2] Mde Pkg: Support for MPAM ACPI Table
> >
> >
> >
> >
> >
> > On Aug 19, 2022, at 1:26 AM, Rohit Mathew <rohit.mat...@arm.com> wrote:
> > > >
> > > > Hi Swatisri,
> > > >
> > > > Thanks for the patch. Please find my comments inline marked [Rohit] -
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Name
> > > > > via groups.io
> > > > > Sent: 16 August 2022 21:18
> > > > > To: devel@edk2.groups.io; Sami Mujawar <sami.muja...@arm.com> ;
> > > > > Alexei Fedorov <alexei.fedo...@arm.com> ;
> > > > > michael.d.kin...@intel.com;
> > > > > gaolim...@byosoft.com.cn; zhiguang....@intel.com
> > > > > Cc: Swatisri Kantamsetti <swatis...@nvidia.com>
> > > > > Subject: [edk2-devel] [PATCH 1/2] Mde Pkg: Support for MPAM ACPI
> > > > > Table
> > > > >
> > > > > From: Swatisri Kantamsetti <swatis...@nvidia.com>
> > > > >
> > > > > Added MPAM table header, MSC and Resource Node info structures
> > > > >
> > > > > Signed-off-by: Swatisri Kantamsetti <swatis...@nvidia.com>
> > > > > ---
> > > > > MdePkg/Include/IndustryStandard/Acpi64.h | 5 ++
> > > > > MdePkg/Include/IndustryStandard/Mpam.h | 69
> > > > > ++++++++++++++++++++++++
> > > > > 2 files changed, 74 insertions(+)
> > > > > create mode 100644 MdePkg/Include/IndustryStandard/Mpam.h
> > > > >
> > > > > diff --git a/MdePkg/Include/IndustryStandard/Acpi64.h
> > > > > b/MdePkg/Include/IndustryStandard/Acpi64.h
> > > > > index fe5ebfac2b..e54f631186 100644
> > > > > --- a/MdePkg/Include/IndustryStandard/Acpi64.h
> > > > > +++ b/MdePkg/Include/IndustryStandard/Acpi64.h
> > > > > @@ -2952,6 +2952,11 @@ typedef struct {
> > > > > ///
> > > > > #define
> > > > > EFI_ACPI_6_4_PROCESSOR_PROPERTIES_TOPOLOGY_TABLE_STRUCTURE_SI
> > > > > GNATURE SIGNATURE_32('P', 'P', 'T', 'T')
> > > > >
> > > > > +///
> > > > > +/// "MPAM" Memory System Resource Partitioning And Monitoring Table
> > > > > ///
> > > > > +#define
> > > > > +EFI_ACPI_6_4_MEMORY_SYSTEM_RESOURCE_PARTITIONING_MONITORI
> > > > > NG_TABLE_STRUC
> > > > > +TURE_SIGNATURE SIGNATURE_32('M', 'P', 'A', 'M')
> > > > > +
> > > > > ///
> > > > > /// "PSDT" Persistent System Description Table /// diff --git
> > > > > a/MdePkg/Include/IndustryStandard/Mpam.h
> > > > > b/MdePkg/Include/IndustryStandard/Mpam.h
> > > > > new file mode 100644
> > > > > index 0000000000..e0f75f0114
> > > > > --- /dev/null
> > > > > +++ b/MdePkg/Include/IndustryStandard/Mpam.h
> > > > > @@ -0,0 +1,69 @@
> > > > > +/** @file
> > > > > + ACPI Memory System Resource Partitioning And Monitoring (MPAM)
> > > > > + as specified in ARM spec DEN0065
> > > > > +
> > > > > + Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
> > > > > + Copyright (c) 2022, ARM Limited. All rights reserved.
> > > > > + SPDX-License-Identifier: BSD-2-Clause-Patent **/
> > > > > +
> > > > > +#ifndef _MPAM_H_
> > > > > +#define _MPAM_H_
> > > > > +
> > > > > +#pragma pack(1)
> > > > > +
> > > > > +///
> > > > > +/// Memory System Resource Partitioning and Monitoring Table (MPAM)
> > > > > ///
> > > > > +typedef struct {
> > > > > + EFI_ACPI_DESCRIPTION_HEADER Header;
> > > > > + UINT32 NumNodes;
> > > > > + UINT32 NodeOffset;
> > > > > + UINT32 Reserved;
> > > > > +}
> > > > > +EFI_ACPI_6_4_MEMORY_SYSTEM_RESOURCE_PARTITIONING_MONITORI
> > > > > NG_TABLE_HEADE
> > > > > +R;
> > > >
> > > > [Rohit] Shouldn't the header be followed by MSC node body type as
> > > > defined in MPAM ACPI 1.0, section 2, table 3 - The MPAM table and
> > > > section 2.1, table 4 - MSC Node body?
> > > >
> > > >
> > > >
> > > > > +
> > > > > +///
> > > > > +/// MPAM Revision (as defined in ACPI 6.4 spec.) /// #define
> > > > > +EFI_ACPI_6_4_MEMORY_SYSTEM_RESOURCE_PARTITIONING_MONITORI
> > > > > NG_TABLE_REVIS
> > > > > +ION 0x01
> > > > > +
> > > > > +///
> > > > > +/// Memory System Controller Node Structure ///
> > > > > +
> > > > > +typedef struct {
> > > > > + UINT16 Length;
> > > > > + UINT16 Reserved;
> > > > > + UINT32 Identifier;
> > > > > + UINT64 BaseAddress;
> > > > > + UINT32 MmioSize;
> > > > > + UINT32 OverflowInterrupt;
> > > > > + UINT32 OverflowInterruptFlags;
> > > >
> > > > [Rohit] Would it be better to have a type (possibly bitfield struct)
> > > > instead of a plain UINT32 for Flags? (MPAM ACPI 1.0, section 2.1.1,
> > > > table 5 - Interrupt flags)
> > > >
> > > >
> > > >
> > > Probably better NOT to use bitfields in APIs that are produced and
> > > consumed by different worlds. While the the UEFI does speak to the bit
> > > order of or a bitfield the rules around packing of bitfields is compiler
> > > defined.
> > >
> > > I just saw a bug last week with bitfield compatibility that was
> > > introduced by clang fixing its -mms-bitfields implementation. The GCC
> > > rules for packing bitfields is different than VC++ so that is why the
> > > compiler flag -mms-bitfields exists in the 1st place . A clang
> > > -mms-bitfields bug got fixed and it broke the code as the extra padding
> > > required by VC++ got added to the bitfield.
> >
> > [Rohit] Thanks for bringing this point. I think, this type could be left
> > untouched in that case.
> >
> > > Thanks,
> > >
> > > Andrew Fish
> > >
> > >
> > >
> > > > > + UINT32 Reserved1;
> > > > > + UINT32 OverflowInterruptAff;
> > > > > + UINT32 ErrorInterrupt;
> > > > > + UINT32 ErrorInterruptFlags;
> > > >
> > > > [Rohit ] Same comment as before above.
> > > >
> > > >
> > > >
> > > > > + UINT32 Reserved2;
> > > > > + UINT32 ErrorInterruptAff;
> > > > > + UINT32 MaxNRdyUsec;
> > > > > + UINT64 LinkedDeviceHwId;
> > > > > + UINT32 LinkedDeviceInstanceHwId;
> > > > > + UINT32 NumResourceNodes;
> > > > > +} EFI_ACPI_6_4_MPAM_MSC_NODE;
> > > > > +
> > > > > +///
> > > > > +/// Resource Node Structure
> > > > > +///
> > > > > +
> > > > > +typedef struct {
> > > > > + UINT32 Identifier;
> > > > > + UINT8 RisIndex;
> > > > > + UINT16 Reserved1;
> > > > > + UINT8 LocatorType;
> > > > > + UINT64 Locator;
> > > >
> > > > [Rohit ] Shouldn't " Locator " field be 12 bytes in size, possibly a
> > > > separate type? (MPAM ACPI 1.0, section 2.2, table 7 - Resource node and
> > > > section 2.3.2 table 10 - locator descriptor)
> > > >
> > > >
> > > >
> > > > > + UINT32 NumFuncDep;
> > > > > +} EFI_ACPI_6_4_MPAM_RESOURCE_NODE;
> > > >
> > > > [Rohit] Since "NumFuncDep" field is part of
> > > > EFI_ACPI_6_4_MPAM_RESOURCE_NODE type and this could be non-zero, should
> > > > we also need the type for functional dependency descriptors? (MPAM ACPI
> > > > 1.0, section 2.2.1, table 8 - Functional dependency descriptor)
> > > >
> > > > [Rohit] Also, could some of the commonly used macros be added to this
> > > > header, please? (location types, MPAM interrupt mode, interrupt types,
> > > > affinity type, etc)
> > > >
> > > >
> > > >
> > > > > +
> > > > > +#pragma pack()
> > > > > +
> > > > > +#endif
> > > > > --
> > > > > 2.17.1
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Regards,
> > > > Rohit
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