Re: [Xen-devel] [PATCH v4 2/8] pc: move igd support code to igd.c

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Gerd Hoffmann [mailto:kraxel@xxxxxxxxxx]
> Sent: Wednesday, March 09, 2016 11:08 PM
> 
>   Hi,
> 
> > +/* Here we just expose minimal host bridge offset subset. */
> > +static const IGDHostInfo igd_host_bridge_infos[] = {
> > +    {0x08, 2},  /* revision id */
> > +    {0x2c, 2},  /* sybsystem vendor id */
> > +    {0x2e, 2},  /* sybsystem id */
> 
> Can anyone clarify where this comes from?

Add Allen who is the original author.

> 
> Setting the subsystem id without also setting the pci id looks wrong,
> given that each pci id has its own subsystem id namespace.
> 
> Testing (with alex vfio patches) shows that dropping this seems to have
> no bad effects.  Things are still working fine of we only set these ...

It's possible that original list may become more than what current
driver requires...

> 
> > +    {0x50, 2},  /* SNB: processor graphics control register */
> > +    {0x52, 2},  /* processor graphics control register */
> > +    {0xa4, 4},  /* SNB: graphics base of stolen memory */
> > +    {0xa8, 4},  /* SNB: base of GTT stolen memory */
> 
> ... gfx registers in host bridge pci config space.
> 

Yes.

Thanks
Kevin
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