Do we have some topic to discuss for the Linaro-open-disscussions next week?
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> 1. Re: LOD Call notes: 22 March 2022 - vCPU Hotplug Update
> (Jonathan Cameron)
> Message: 1
> Date: Wed, 13 Apr 2022 19:17:32 +0100
> From: Jonathan Cameron <Jonathan.Cameron(a)Huawei.com>
> Subject: [Linaro-open-discussions] Re: LOD Call notes: 22 March 2022 -
> vCPU Hotplug Update
> To: Ilkka Koskinen <ilkka(a)os.amperecomputing.com>
> Cc: linaro-open-discussions(a)op-lists.linaro.org
> Message-ID: <20220413191732.00000e4e(a)Huawei.com>
> Content-Type: text/plain; charset="US-ASCII"
> On Thu, 31 Mar 2022 11:47:26 -0700 (PDT)
> Ilkka Koskinen <ilkka(a)os.amperecomputing.com> wrote:
>> Hi everyone,
>> On Tue, 22 Mar 2022, Jonathan Cameron via Linaro-open-discussions wrote:
>>> Hi All,
>>> A quick set of notes on the discussion on vCPU hotplug.
>>> Great to have Ed join the discussion. If we are going to
>>> have further calls on this topic we may want to move the time to be
>>> more friendly for the US.
>>> Current status
>>> * ACPI spec change via code first route approved.
>>> * Kernel patches being reworked / rebased by ARM. Expected to be sent
>>> out in 5.19 cycle.
>>> * QEMU patches being updated by Huawei. Will do at least some light testing
>>> and then push out a public git tree so that others can test - will aim
>>> to do this so it aligns with kernel code availability.
>>> * Ed (Ampere) gave an update to say they are interested in pushing this
>>> forwards ASAP and have customer / OS vendor engagement which will be
>>> very useful in moving towards a complete solution, particularly ensuring
>>> good test coverage etc.
>>> Noted that current QEMU patches may not cover all corner cases, for example
>>> live migration of VMs that have vCPUs hotplugged. Might 'just work'
>>> but we haven't tested it yet so probably not.
>>> Given we didn't really add anything on DOE / SPDM over previous calls,
>>> I don't plan to send out anything on that topic this time.
>>> Thanks to Joyce for hosting the call. If I noted down anything wrong,
>>> or incomplete let the list know.
>>> Linaro-open-discussions mailing list -- linaro-open-discussions(a)op-lists.linaro.org
>> Thanks for the great meeting and the update! As Ed mentioned (and you
>> wrote above), we're interested in joining the vCPU Hotplug development.
> Hi Ilkka
> Great to have you on board for this.
> Status wise, on QEMU side we have the new interface up and running
> (it was a whole 2 lines of code once we'd dealt with some rebasing related issues).
> Rather more changes were needed to make it work sensibly on top of Gavin Shan's
> QEMU topology configuration patch set.
> The code going through some light internal review before we put it up somewhere
> public. Note it's definitely not production quality code but it is somewhere
> to start from. Given Easter related vacations I doubt we'll get enough
> eyes on it until next week.
> We were thrown briefly by the fact there is a recently added
> apcica/actbl2.h entry for MADT_ONLINE_CAPABLE but it's a different bit.
> Seems x86 folk wanted something similar last year. We'll have to do something
> ugly in ACPICA to mangle the name for the new bit to avoid that collision.
> Lorenzo, I'm assuming the ACPCIA one line patch to add that define is
> something the ARM team will deal with?
> There are some known limitations though that we'll need to sort out before
> upstreaming the QEMU support. One of which is SVE currently breaks things.
> Plenty of time though as kernel needs to be upstream first anyway.
> Testing wise we are using QEMU on top of QEMU so we can poke corners of the
> architecture don't have hardware for (e.g. SVE :). Even on a rubbish x86
> desktop it's not that slow :)
> Lorenzo, any update on kernel side of things or expected time scale for
> more information?
> Obviously we have some hacked patches based on Salil's original proposal
> that sanity check the QEMU side of things but I suspect the final version
> will look rather different :)
> One question on the spec change for Lorenzo. It's not entirely clear
> but I think we should not be using _MAT when 'hotplugging' the vCPUs?
> For now the QEMU code provides the relevant entries anyway but
> it would be nice to drop that if not necessary (it's not a huge
> amount of code or complexity though so not a big thing either way).
> Thanks and an early happy Easter to those celebrating on Sunday.
>> Br, Ilkka
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> End of Linaro-open-discussions Digest, Vol 19, Issue 1