Re: [Qemu-devel] Headsup: windows virtio networking does not work on current git

[Vadim Rozenfeld]

On Thu, 2013-02-07 at 12:18 +0200, Michael S. Tsirkin wrote:
> On Thu, Feb 07, 2013 at 08:24:10PM +1100, Vadim Rozenfeld wrote:
> > On Thu, 2013-02-07 at 11:33 +1030, Rusty Russell wrote:
> > > Vadim Rozenfeld <address@hidden> writes:
> > > > On Tue, 2013-02-05 at 13:58 +0200, Michael S. Tsirkin wrote:
> > > >> On Tue, Feb 05, 2013 at 03:45:38PM +0400, Michael Tokarev wrote:
> > > >>  Is it really
> > > >> > that bad that the config space size changed?  Why it has this effect?
> > > > Because in this case it's hard to distinguish between resource's
> > > > corruption and HW update.
> > > 
> > > But it's also true that if we'd incremented revid you'd have the same
> > > failure in this case, right?
> > 
> > It depends. If we have explicitly specified revision id in inf file and
> > this id doesn't mach the new revision id, Windows will not try to load
> > the "incompatible" driver, and finish up with "device driver not found"
> > dialog.
> > 
> > Best regards,
> > Vadim.
> >   
> > > 
> > > Cheers,
> > > Rusty.
> 
> Well that's all in theory, in practice it does not look like revision ID
> is specified in the NetKVM inf so this won't work?
> 
> From what I see this inf specifies:
> 
> NetKVM/wlh/netkvm.inf:%kvmnet6.DeviceDesc%    = kvmnet6.ndi, 
> PCI\VEN_1AF4&DEV_1000&SUBSYS_00011AF4
> NetKVM/wxp/netkvm.inf:%kvmnet5.DeviceDesc%    = kvmnet5.ndi, 
> PCI\VEN_1AF4&DEV_1000&SUBSYS_00011AF4
> NetKVM/wxp/netkvm2k.inf:%kvmnet5.DeviceDesc%    = kvmnet5.ndi, 
> PCI\VEN_1AF4&DEV_1000&SUBSYS_00011AF4
> 
> So we can tweak any of vendor device and subsystem id.
> 
Unfortunately, it won't. Only balloon has revision id, specified as a
part of device HW descriptor. But it's only because virtio doesn't use 
revision ids. Otherwise it differential will be there. 
> 
> Changing subsystem vendor ID actually will be completely
> transparent to linux which for some reason looks at the
> subsystem device ID (why? no idea) but not the subsystem vendor ID.
> Of course this requires a valid vendor ID, getting this
> costs $3000 I think.
> We could tweak device ID too but that might break some other guests
> which don't copy the crazy 'replace device id with subsystem device id'
> logic from Linux.
>