Re: [PATCH 3/3] nvme-pci: disable namespace identifiers for Qemu controllers

[Klaus Jensen <its@irrelevant.dk>]

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On Apr 13 17:50, Christoph Hellwig wrote:
> On Wed, Apr 13, 2022 at 05:49:29PM +0200, Klaus Jensen wrote:
> > This means that the 'use-intel-id' compatibility parameter may cause a
> > 5.2 nvme device to present itself with the Intel PCI vendor/device id,
> > either because the user explicitly set it, or because the machine is
> > launched using a pre-5.2 machine type (i.e. `-machine pc-q35-5.1`),
> > which you would normally do if you want launch an existing VM on a new
> > version of QEMU.
> 
> But if it presents an old machine it also shouldn't support a new
> identify call, right?
> 

You are absolutely right in the case of live-migration, but hw/nvme is
marked unmigratable, so we do not worry about that.

We probably screwed up with the compatibility parameter here, since it
really only guarantees the id and some headaches for you as driver
maintainer. I'm sorry about that - I'll keep this in mind for the
future.

Regardless, the fact remains that it is possible to have a device with a
buggy uuid namespace descriptor using the Intel identifier, so we should
add the quirk for that as well.

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