Re: [Qemu-devel] [Xen-devel] [v2][PATCH] libxl: add one machine property to support IGD GFX passthrough

[Ian Campbell <Ian.Campbell@citrix.com>]

On Wed, 2015-02-11 at 10:45 +0800, Chen, Tiejun wrote:
> On 2015/2/9 19:05, Ian Campbell wrote:
> > On Mon, 2015-02-09 at 14:28 +0800, Chen, Tiejun wrote:
> >
> >> What about this?
> >
> > I've not read the code in detail,since I'm travelling but from a quick
> > glance it looks to be implementing the sort of thing I meant, thanks.
> 
> Thanks for your time.
> 
> >
> > A couple of higher level comments:
> >
> > I'd suggest to put the code for reading the vid/did into a helper
> > function so it can be reused.
> 
> Looks good.
> 
> >
> > You might like to optionally consider add a forcing option somehow so
> > that people with new devices not in the list can control things without
> > the need to recompile (e.g. gfx_passthru_kind_override?). Perhaps that
> > isn't needed for a first cut though and it would be a libxl API so
> > thought required.
> 
> What about 'gfx_passthru_force'? Because what we're doing is, we want to 
> make sure if we have a such a IGD that needs to workaround by posting a 
> parameter to qemu. So in case of non-listed devices we just need to 
> provide a bool to force this regardless of that real device.

If we are going to do this then I think we need to arrange for the
interface to be able to express the need to force the workarounds for a
particular device. IOW a boolean will not suffice since it doesn't
indicate that IGD workarounds are needed.

Probably it would be simplest to just leave this functionality out for
the time being and revisit if/when maintaining the list becomes an
annoyance or an end user trips over it.

Ian.