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Re: [Xen-devel] [PATCH 0/2] graphics passthrough with VT-d

To: "Han, Weidong" <weidong.han@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 0/2] graphics passthrough with VT-d
From: Jean Guyader <jean.guyader@xxxxxxxxxx>
Date: Fri, 28 Aug 2009 09:24:31 +0100
Cc: "'xen-devel@xxxxxxxxxxxxxxxxxxx'" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Lin, Ben Y" <ben.y.lin@xxxxxxxxx>, "Kay, Allen M" <allen.m.kay@xxxxxxxxx>, Fraser <Keir.Fraser@xxxxxxxxxxxxx>, Keir, "'bengheng@xxxxxxxxxxxxxx'" <bengheng@xxxxxxxxxxxxxx>
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On Fri, Aug 28, 2009 at 03:53:56AM -0400, Han, Weidong wrote:
> Hi all,
> Recently, more and more people are interesting in gfx passthrough. But now 
> xen-unstable doesn't support it, although some guys (Jean Guyader, Beng Heng, 
> Ng) posted gfx passthrough patches. If xen-unstable includes gfx passthrough 
> support, people can be easy to try it.
> gfx passthrough is more complicated than other PCI device passthrough such as 
> NIC, and is hard to use a generic approach for all gfx passthrough. But there 
> are some necessary changes for gfx passthrough:
>   1. disable emulated VGA adapter, instead use passthroughed gfx
>   2. load VGA bios of the gfx to guest
>   3. passthrough legacy VGA IO ports and MMIOs to guest
> This patchset implements above common changes. Based on the common changes, 
> we are investigating to support more gfx cards and guest OSs. We will post 
> the hacks in future.
> The patchset supports to passthrough the primary gfx and discrete gfx. With 
> the patchset, virtualization friendly gfx cards can be passthroughed (e.g. 
> Nvidia FX3800), IGD and many discrete gfx cards are not supported yet. 
> This is easy to use, the only difference from other PCI passthrough is to add 
> following lines to hvm configure file:
> #----------------------------------------------------------------------------------------
> # 0: no gfx passthru, 1: IGD passthru, 2: discrete gfx passthru, default is 0
> gfx_passthru=2
> and also pls passthrough a USB controller for keyboard/mouse use in guest. 
> (Now there are some issues on USB controller passthrough with pv-ops dom0, so 
> currently prefer to use 2.6.18 dom0.)

Once we have those patch inside xen-unstable, I could commit the patch we have 
for XCI
to share the host keyboard/mouse with multiple vms.

> The patchset is as follows:
> 1. PATCH 1/2: changes in xen-unstable
>       - retrieves VGA bios from host VGA BIOS address (0xC0000), then load it 
> to guest VGA BIOS address (This is the same with XCI).
>       - Enlarge guest MMIO range to contain gfx card's large memory 
>       - add a config option 'gfx_passthru' for gfx passthrough
> 2. PATCH 2/2: changes in QEMU
>       - disable emulated VGA adapter 
>       - register/unregister legacy VGA I/O ports and MMIOs


Has those patch been tested with an intel IGD?

Because I think they are some pieces missing: 
        - GMCH mapping in the guest.
        - VID DID pt for the host bridge (for linux hvm guest).
        - TOM pass through for winxp guest.


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