[+] Adding back LOD mailing list

Hi Leo,

From: Leonardo Augusto Guimarães Garcia leonardo.garcia@linaro.org Sent: Wednesday, August 30, 2023 1:59 PM To: Marcin Juszkiewicz marcin.juszkiewicz@linaro.org; Jonathan Cameron jonathan.cameron@huawei.com; Salil Mehta salil.mehta@huawei.com Cc: Lorenzo Pieralisi lorenzo.pieralisi@linaro.org; Joyce Qi joyce.qi@linaro.org; James Morse james.morse@arm.com; Salil Mehta salil.mehta@opnsrc.net; Radoslaw Biernacki rad@semihalf.com; Leif Lindholm quic_llindhol@quicinc.com; Peter Maydell peter.maydell@linaro.org Subject: Re: [Linaro-open-discussions] Re: About the LOD next week (Aug 22th)

On 2023/08/30 09:11, Marcin Juszkiewicz wrote:

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W dniu 30.08.2023 o 13:59, Jonathan Cameron pisze:

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Salil Mehta salil.mehta@huawei.com wrote:

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But I am not sure about qemu-sbsa. Maybe someone can help throw light on the goals of qemu-sbsa and who wants it?

Architecture verification - not use as a VM except for that purpose. It's not a replacement for virt - purpose is completely different.

Of the current machines in QEMU the only one that I can see vCPU HP mattering for is virt as that's the one targeting cloud VMs etc.

Clouds use 'virt' as it was made for that purpose. And vCPU hotplug may have sense there.

SBSA Reference Platform (sbsa-ref in QEMU) is emulation of physical computer (similar to 'q35' in x86-64 world). It does not use any of virtio expansions but emulate expansion cards so you get 'bochs-display' instead of 'virtio-gpu', 'ahci' instead of 'virtio-blk/scsi' etc.

The goal is to have virtual system which can be used to check how operating systems behave on SBSA hardware.

We are going for SBSA level 3 compliance and we are getting closer.

Does vCPU hotplug make sense for sbsa-ref? Probably not as you do not hotplug cpus into your physical box, right?

This is correct. Today we don't have Arm physical machines that support CPUs hot plug/unplug.

Given that, I agree with Jonathan that the cVPU hot plug/unplug code don't need to worry about SBSA QEMU implementation. There shouldn't be any use case for that in the foreseeable future.

Agreed for the reasons mentioned above. Thanks again for the confirmation.

Thanks Salil.

Cheers,

Leo