Re: [Qemu-ppc] [Qemu-devel] [qemu-s390x] [RFC PATCH 1/3] hw/Kconfig: PCI bus implies PCI_DEVICES

[Collin Walling]

On 7/17/19 9:52 AM, Paolo Bonzini wrote:
> On 17/07/19 14:59, Collin Walling wrote:
> > On 7/16/19 11:04 AM, Thomas Huth wrote:
> > > On 16/07/2019 15.06, Markus Armbruster wrote:
> > > > Paolo Bonzini <address@hidden> writes:
> > > >
> > > > > On 15/07/19 18:12, Cornelia Huck wrote:
> > > > > > > Is it INTx vs. MSI vs. MSI-X?
> > > > > >
> > > > > > I think for s390x we need (INTx || MSI) vs MSI-X...
> > > > >
> > > > > I think MSI vs MSI-X is just how it's configured, not the actual
> > > > > behavior, so it should be irrelevant.
> > > >
> > > > My best guesses from confusing information, please correct
> > > > misunderstandings:
> > > >
> > > > 1. PCI devices need to support MSI or MSI-X to work with s390x.
> > >
> > > I think Cornelia mentioned that we might even require MSI-X there ...
> > > Collin (being listed as "S390 PCI" maintainer), can you confirm?
> >
> > MSI-X is mandatory for PCI devices in the s390 architecture.
>
> How are MSI and MSI-X distinguished?
>
> Paolo

PCI host plugging will check for the MSI-X capability on the
PCI device. If the MSI-X cap is missing, we fail device plugging.
We do not check for MSI. Only MSI-X.

Specifically, the capability is represented by PCI_CAP_ID_MSIX
in pci_regs.h