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Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode
From: |
Eduardo Habkost |
Subject: |
Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode |
Date: |
Wed, 26 Aug 2020 10:04:41 -0400 |
On Wed, Aug 26, 2020 at 02:38:49PM +0200, Igor Mammedov wrote:
> On Fri, 21 Aug 2020 17:12:19 -0500
> Babu Moger <babu.moger@amd.com> wrote:
>
> > To support some of the complex topology, we introduced EPYC mode apicid
> > decode.
> > But, EPYC mode decode is running into problems. Also it can become quite a
> > maintenance problem in the future. So, it was decided to remove that code
> > and
> > use the generic decode which works for majority of the topology. Most of the
> > SPECed configuration would work just fine. With some non-SPECed user inputs,
> > it will create some sub-optimal configuration.
> > Here is the discussion thread.
> > c0bcc1a6-1d84-a6e7-e468-d5b437c1b254@amd.com/">https://lore.kernel.org/qemu-devel/c0bcc1a6-1d84-a6e7-e468-d5b437c1b254@amd.com/
> >
> > This series removes all the EPYC mode specific apicid changes and use the
> > generic
> > apicid decode.
>
> the main difference between EPYC and all other CPUs is that
> it requires numa configuration (it's not optional)
> so we need an extra patch on top of this series to enfoce that, i.e:
>
> if (epyc && !numa)
> error("EPYC cpu requires numa to be configured")
>
> I think there was a patch in previous revisions that aimed for this.
> Simplest form would be above snippet.
>
> More complex one, would be moving auto_enable_numa from MachineClass to
> MachineState so we can change it at runtime if EPYC is used. That should
> take care of use case where user hasn't provided -numa.
This sounds like a good solution. It actually sounds simpler
than the alternatives (which just move the complexity to other
components).
We can keep MachineClass::auto_enable_numa as is, and just use it
to initialize the default value of MachineState::auto_enable_numa.
--
Eduardo
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, (continued)
- RE: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Babu Moger, 2020/08/26
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Dr. David Alan Gilbert, 2020/08/26
- RE: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Babu Moger, 2020/08/26
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Igor Mammedov, 2020/08/27
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Daniel P . Berrangé, 2020/08/28
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Igor Mammedov, 2020/08/28
- RE: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Babu Moger, 2020/08/28
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Igor Mammedov, 2020/08/28
Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode,
Eduardo Habkost <=