Re: [Qemu-devel] [PATCH v2 for-2.5] virtio-pci: Set the QEMU_PCI_CAP_EXPRESS capability early in its DeviceClass realize method

[Michael S. Tsirkin]

On Wed, Dec 02, 2015 at 07:12:47PM +0200, Shmulik Ladkani wrote:
> Hi Michael,
> 
> On Wed, 2 Dec 2015 18:49:24 +0200 "Michael S. Tsirkin" <address@hidden> wrote:
> > On Wed, Dec 02, 2015 at 05:11:28PM +0200, Marcel Apfelbaum wrote:
> > > The only thing I want to mention here, (see earlier discussion: 
> > > https://www.mail-archive.com/address@hidden/msg338963.html)
> > > is that in some cases the PCI config space will have PCIe length, even if 
> > > the device is not express.
> > > 
> > > To be more precise, the only interesting scenario is when we plug a 
> > > virtio device directly into
> > > the root complex, in this case we'll have a PCI device with a PCIe config 
> > > space.
> > > 
> > > However this happens for other devices as well, it looks like a common 
> > > practice.
> > 
> > Problem is, if this happens migration breaks as we
> > changed config space size from 2.4.
> 
> Correct me if wrong, but as long as a pre 2.5 hardware is used, Marcel's
> x-disable-pcie gets on (see HW_COMPAT_2_4), thus the device will not be
> a "pci_is_express", and it will have a small config space size. Isn't it
> so?
> 
> Regards,
> Shmulik

OK. Still, I do not want to migrate 4k of config space
for pci devices.

-- 
MST