Re: Dropped/disabled NVME support in qemu

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Cc'ing NVMe emulation maintainers.

On 12/21/20 6:12 AM, Guenter Roeck wrote:
> Hi all,
> 
> since qemu v5.1, nvme support has been dropped from several architectures.
> Well, it was not exactly dropped, but disabled.
> 
> On those architectures, trying to boot from an nvme drive now results
> in the following or a similar error message.
> 
> qemu-system-alpha: -device nvme,serial=foo,drive=d0: MSI-X is not supported by interrupt controller
> 
> This is the result of the following two commits.
> 
> fbf2e5375e ("hw/block/nvme: Verify msix_vector_use() returned value")
> 1c0c2163aa ("hw/block/nvme: verify msix_init_exclusive_bar() return value")
> 
> Affected architectures are alpha, parisc, ppc, sh, and sparc, and every other
> architecture/platform where the interrupt controller does not support MSI-X.
> After reverting above patches, I can boot from nvme again.
> 
> This does not really matter for me - I run my own versions of qemu anyway,
> and don't mind carrying reverts if I have to. However, for my education,
> I would like to understand why nvme support was disabled, especially since
> it seemed to work for me just fine for years. Can someone please explain ?
> 
> Thanks,
> Guenter
>