[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <53A692F9.3060200@intel.com>
Date: Sun, 22 Jun 2014 16:25:29 +0800
From: "Chen, Tiejun" <tiejun.chen@...el.com>
To: Paolo Bonzini <pbonzini@...hat.com>, daniel.vetter@...ll.ch,
jani.nikula@...ux.intel.com, airlied@...ux.ie
CC: intel-gfx@...ts.freedesktop.org, xen-devel@...ts.xensource.com,
linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
qemu-devel@...gnu.org
Subject: Re: [RFC][PATCH] gpu:drm:i915:intel_detect_pch: back to check devfn
instead of check class type
On 2014/6/20 20:48, Paolo Bonzini wrote:
> Il 19/06/2014 11:53, Tiejun Chen ha scritto:
>> so this mean that isa bridge is still represented with Dev31:Func0
>> like the native OS. Furthermore, currently we're pushing VGA
>> passthrough support into qemu upstream, and with some discussion,
>> we wouldn't set the bridge class type and just expose this devfn.
>
> Even this is not really optimal. It just happens to work just because
> QEMU's machine is currently a PCI machine with the ISA bridge on 00:01.0.
>
> As soon as you'll try doing integrated graphics passthrough on a PCIe
> machine type (such as QEMU's "-M q35") things will break down just as
> badly.
>
Sorry, I can't understand why this is related to the ISA bridge, 00:01.0
or even other PCIe machine type.
In virtualized case we always need to create this ISA bridge as a devfn,
00:15.0, work for the i915 driver to support IGD passthrough.
In qemu-xen-traditional, this ISA bridge is already created as follows:
1> We set this ISA type explicitly;
2> We register that as 00:15.0.
In qemu-upstream, as you commented we can't create this as a ISA class
type explicitly. So we compromise by faking this ISA bridge without ISA
class type setting (as I recall you already said this way is slightly
better). Maybe we will figure better way in the future. But anyway, this
is always registered as 00:15.0, right? So I think the i915 driver can
go back to probe the devfn like the native environment.
If I'm wrong please correct me.
Thanks
Tiejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists