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?
2. We want a way to Kconfig the PCI devices that work, i.e. only the
ones that support MSI or MSI-X.
I don't like calling devices without any MSI capability "classic" or
"conventional devices". I'd rather call them "MSI-capable" or
"MSI/MSI-X devices".
But you still need a config switch that you can set to enable the
non-MSI devices ... what's so wrong with "conventional" if that's even
the wording from the PCI SIG?
Since PCI-E devices must implement MSI or MSI-X, we could perhaps
configure just the PCI-E devices for s390x. No need to invent a new
name then. Do we even have device models that can do MSI but not E?
I don't know if anybody ever tried a non-virtio PCIe device from QEMU on
s390x ... I guess there will be quite a bit of other hurdles, too (e.g.
the Linux driver also has to work without MMIO), so I'm not sure whether
we really want to enable all PCIe devices there...
Thomas