Re: [Qemu-devel] [PATCH 2/7] megasas: Enable MSI-X support

[Michael S. Tsirkin]

On Wed, Apr 16, 2014 at 07:47:37PM +0200, Andreas Färber wrote:
> Am 16.04.2014 19:40, schrieb Michael S. Tsirkin:
> > On Wed, Apr 16, 2014 at 06:48:08PM +0200, Andreas Färber wrote:
> >> Am 16.04.2014 18:32, schrieb Alexander Graf:
> >>>
> >>> On 16.04.14 16:44, Hannes Reinecke wrote:
> >>>> MSI-X support has been fixed in qemu, so we can enable it again.
> >>>>
> >>>> Signed-off-by: Hannes Reinecke <address@hidden>
> >>>> ---
> >>>>   hw/scsi/megasas.c | 19 ++++++-------------
> >>>>   1 file changed, 6 insertions(+), 13 deletions(-)
> >>>>
> >>>> diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c
> >>>> index 1781525..df45286 100644
> >>>> --- a/hw/scsi/megasas.c
> >>>> +++ b/hw/scsi/megasas.c
> >>>> @@ -2084,7 +2084,8 @@ static const VMStateDescription vmstate_megasas = {
> >>>>       .minimum_version_id = 0,
> >>>>       .minimum_version_id_old = 0,
> >>>>       .fields      = (VMStateField[]) {
> >>>> -        VMSTATE_PCI_DEVICE(parent_obj, MegasasState),
> >>>> +        VMSTATE_PCIE_DEVICE(parent_obj, MegasasState),
> >>>> +        VMSTATE_MSIX(parent_obj, MegasasState),
> >>>
> >>> This requires a version change for vmstate, no?
> >>
> >> The PCI -> PCIE change yes. mst might have objections for bumping an x86
> >> PCI device?
> > 
> > Yes.
> > It should be possible to make this conditional on having a pcie
> > capability, and disable pcie capability for old pc versions.
> 
> I did have a patch merging their vmstate_ structs based on some test in
> the series I ping'ed, unfortunately the difference was mostly config
> space size, so not immediately obvious how to set via compat_props, but
> likely solvable somehow.

Check pci_is_express ?

> >> The MSIX addition should be safe AFAICT since old versions would not
> >> enable MSI-X.
> > 
> > Yes but I don't see a code like this - where's code in PC
> > disabling msix for old versions?
> 
> The default value for use_msix (use-msix?) in v2 is already false, so no
> need to set it to false again in compat_props?
> 
> Andreas

Ah, I didn't notice that. Sure, if it's off by default there's
no need for compat code.

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