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

[Michael S. Tsirkin]

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.

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.

-- 
MST