Re: [edk2-devel] PATCH v1 1/1 MdePkg: Remove Itanium leftover data structure

["Zimmer, Vincent" <vincent.zimmer@intel.com>]

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I would suggest going forward to remove itanium hand-off information.  Now that the stable table has been dropped the community can assess the impact of this change over the next few months.

I can also follow-up on some of the more formal PI spec clean-up for elision of this info targeting a post PI1.8 document, too.


Vincent

From: Pawel Polawski <ppolawsk@redhat.com>
Sent: Tuesday, March 7, 2023 4:43 AM
To: devel@edk2.groups.io; thomas.lendacky@amd.com; Ni, Ray <ray.ni@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>; Zimmer, Vincent <vincent.zimmer@intel.com>; Kirkendall, Garrett <Garrett.Kirkendall@amd.com>
Cc: Gao, Liming <gaoliming@byosoft.com.cn>; Liu, Zhiguang <zhiguang.liu@intel.com>
Subject: Re: [edk2-devel] PATCH v1 1/1 MdePkg: Remove Itanium leftover data structure

Hi all,

I would like to kindly remind that the final decision on this topic has not been made yet.
If I understand correctly we need some more expertise from Intel about potential issues
caused by this change on binary based images (which assumes fixed size for this data structure and
cannot be changed)?

Best regards,
Pawel

On Tue, Jan 17, 2023 at 1:46 PM Paweł Poławski <ppolawsk@redhat.com<mailto:ppolawsk@redhat.com>> wrote:
Hi all,

Just to let you know: I performed a test with this modified version
of EDK2 and 1500 vCPU set in Qemu config. The test ended up with
success. I can confirm that space saved by removing Itanium data
structure allows to allocate more than 1024 vCPU using KVM accelerator.

On thing to note - to test this KVM needs to be modified, the same with
Qemu. Both - by default has vCPU limits so low that they will be
bottleneck for vCPU now.

Best regards,
Pawel

W dniu 10.01.2023 o 16:32, Lendacky, Thomas via groups.io<http://groups.io> pisze:
> + Garret
>
> On 1/10/23 03:36, Ni, Ray via groups.io<http://groups.io> wrote:
>>>>>> The challenge is that the non-Itanium CPU archs that may depend on
>>>>>> the
>>>>>> current binary layout of these structures.  This could be a binary
>>>>>> PEI CPU module, DXE CPU module, SMM CPU module, MM CPU modules,
>>>>>> UEFI App/Shell App that use the PPI or HOB.
>>
>> The CPU health record is stored in PPI first by SecCore, then saved to
>> HOB by CpuMpPei module.
>> Then CpuDxe gets the record from HOB.
>>
>> If SecCore, CpuMpPei, CpuDxe are built with different structure
>> definition,
>> the compatibility issue appears.
>>
>> The very well know binary separation module today for x86 is Intel's FSP.
>> I am not sure if today customer might use a pre-built FSP binary which
>> is built from
>> version #1 of edk2 while the SecCore and CpuDxe in platform binary are
>> built from
>> a different version of edk2.
>> I don't know how AMD distributes the binary module. + Tom
>>
>> If binary distribution is not adopted yet by industry, I prefer we
>> just update the
>> structure definition.
>>
>>>>>>
>>>>>> Even if we define a new HOB format, we have to decide when it is
>>>>>> used to support compatibility.  Perhaps always keep the current
>>>>>> logic if < 1024 CPUs.  If number of CPUs >= 1024, then produce
>>>>>> the new format of CPU information and update all consumers to
>>>>>> look for new format and use that with higher priority than the
>>>>>> old format.
>>
>> I don't like this approach because it still breaks the case when CPU
>> >=1024 and binary
>> distribution is used.
>>
>>>>>>
>>>>>> Another option is to keep the current format and allow multiple
>>>>>> HOBs to be produced if the CPU information does not fit in the
>>>>>> single HOB size limit of 64KB.  Then update all consumers to
>>>>>> look for 1 or more HOBs to collect all the information.  This
>>>>>> approach removes the CPU number limit as long as there is enough
>>>>>> temp RAM for the multiple HOBs.
>>
>> CpuDxe driver is one of the consumers.
>> 1. Old CpuMpPei (in FSP binary) + new CpuDxe (In Platform binary)
>>       This doesn't work because CpuMpPei still cannot produce the
>> huge-size HOB.
>> 2. New CpuMpPei (in FSP binary) + old CpuDxe (In Platform binary)
>>       This doesn't work because old CpuDxe doesn't look for multiple
>> HOBs.
>>
>>
>>
>>> -----Original Message-----
>>> From: devel@edk2.groups.io<mailto:devel@edk2.groups.io> <devel@edk2.groups.io<mailto:devel@edk2.groups.io>> On Behalf Of Pawel
>>> Polawski
>>> Sent: Tuesday, January 10, 2023 4:19 PM
>>> To: devel@edk2.groups.io<mailto:devel@edk2.groups.io>; Ni, Ray <ray.ni@intel.com<mailto:ray.ni@intel.com>>; Kinney, Michael
>>> D <michael.d.kinney@intel.com<mailto:michael.d.kinney@intel.com>>; Zimmer, Vincent
>>> <vincent.zimmer@intel.com<mailto:vincent.zimmer@intel.com>>
>>> Cc: Gao, Liming <gaoliming@byosoft.com.cn<mailto:gaoliming@byosoft.com.cn>>; Liu, Zhiguang
>>> <zhiguang.liu@intel.com<mailto:zhiguang.liu@intel.com>>
>>> Subject: Re: [edk2-devel] PATCH v1 1/1 MdePkg: Remove Itanium
>>> leftover data structure
>>>
>>> Hi everyone,
>>>
>>> If there is a chance you have some evaluation about this problem
>>> already?
>>>
>>> Best regards,
>>> Pawel
>>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>







--

Paweł Poławski

Red Hat<https://www.redhat.com/> Virtualization

ppolawsk@redhat.com<mailto:ppolawsk@redhat.com>
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