Re: [Xen-devel] [PATCH 1/3] xen/tools: Add 64 bits big bar support

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 16 Aug 2012, Hao, Xudong wrote:
> > -----Original Message-----
> > From: Stefano Stabellini [mailto:stefano.stabellini@xxxxxxxxxxxxx]
> > Sent: Wednesday, August 15, 2012 6:21 PM
> > To: Hao, Xudong
> > Cc: xen-devel@xxxxxxxxxxxxx; Ian Jackson; Zhang, Xiantao
> > Subject: Re: [Xen-devel] [PATCH 1/3] xen/tools: Add 64 bits big bar support
> > 
> > On Wed, 15 Aug 2012, Xudong Hao wrote:
> > > Currently it is assumed PCI device BAR access < 4G memory. If there is 
> > > such a
> > > device whose BAR size is larger than 4G, it must access > 4G memory
> > address.
> > > This patch enable the 64bits big BAR support on hvmloader.
> > >
> > > Signed-off-by: Xiantao Zhang <xiantao.zhang@xxxxxxxxx>
> > > Signed-off-by: Xudong Hao <xudong.hao@xxxxxxxxx>
> > 
> > It is very good to see that this problem has been solved!
> > 
> > Considering that at this point it is too late for the 4.2 release cycle,
> > it might be worth spinning a version of this patches for SeaBIOS and
> > upstream QEMU, that now supports PCI passthrough.
> > 
> 
> Hi, Stefano
> 
> Does Xen already switch to SeaBIOS and upstream QEMU? I saw SeaBIOS does not 
> update for 5 months.

Yes, they are available but not the default yet for HVM guests.
In order to enable upstream QEMU you need to pass:

device_model_version='qemu-xen'

in the VM config file.


> You mean upstream QEMU is this tree git://git.qemu.org/qemu.git ? I heard 
> somebody said PCI device assignment does not work for this tree, but device 
> hot-add/remove works.

qemu-upstream-unstable, the upstream QEMU based tree used with Xen 4.2,
(git://xenbits.xensource.com/qemu-upstream-unstable.git) is based on
QEMU 1.0 and doesn't support PCI passthrough.

However upstream QEMU (git://git.qemu.org/qemu.git) does, and I am going
to rebase on it early when the 4.3 development cycle opens.  So it is
probably a good idea for you to try out upstram QEMU now.
We have a wiki page on how to build and run upstream QEMU on
xen-unstable:

http://wiki.xen.org/wiki/QEMU_Upstream

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