Re: [Xen-devel] Cannot start Fedora 19 HVM domU with VGA passthru

[Gordan Bobic <gordan@xxxxxxxxxx>]

On Thu, 18 Jul 2013 18:55:55 +0800, "Singapore Citizen Mr. Teo En Ming 
(Zhang Enming)" <singapore.mr.teo.en.ming@xxxxxxxxx> wrote:
> On 18/07/2013 18:44, Gordan Bobic wrote:
> > On Thu, 18 Jul 2013 18:40:51 +0800, "Singapore Citizen Mr. Teo En 
> > Ming (Zhang Enming)" <singapore.mr.teo.en.ming@xxxxxxxxx> wrote:
> > > On 18/07/2013 18:29, Gordan Bobic wrote:
> > > > On Thu, 18 Jul 2013 18:20:08 +0800, "Singapore Citizen Mr. Teo En 
> > > > Ming (Zhang Enming)" <singapore.mr.teo.en.ming@xxxxxxxxx> wrote:
> > > > > On 18/07/2013 18:09, Gordan Bobic wrote:
> > > > > > On Thu, 18 Jul 2013 18:07:27 +0800, "Singapore Citizen Mr. Teo 
> > > > > > En Ming (Zhang Enming)" <singapore.mr.teo.en.ming@xxxxxxxxx> 
> > > > > > wrote:
> > > > > > > On 18/07/2013 16:46, Gordan Bobic wrote:
> > > > > > > > On Thu, 18 Jul 2013 16:37:34 +0800, "Singapore Citizen Mr. Teo 
> > > > > > > > En Ming (Zhang Enming)" <singapore.mr.teo.en.ming@xxxxxxxxx> 
> > > > > > > > wrote:
> > > > > > > > > Although Fedora 19 HVM domU with VGA passthrough cannot 
> > > > > > > > > start, Debian
> > > > > > > > > 7.1.0 amd64 HVM domU with VGA passthrough can start. In 
> > > > > > > > > Debian 7.1.0
> > > > > > > > > amd64 HVM domU with VGA passthrough, Intel HD Graphics 4600 
> > > > > > > > > is listed
> > > > > > > > > in lspci -vvv. Please refer to lspci.txt. It is strange that 
> > > > > > > > > no kernel
> > > > > > > > > module is being loaded for Intel HD Graphics 4600. There is 
> > > > > > > > > no "Kernel
> > > > > > > > > driver in use" statement after VGA compatible controller: 
> > > > > > > > > Intel
> > > > > > > > > Corporation Haswell Integrated Graphics Controller (rev 06) 
> > > > > > > > > (prog-if
> > > > > > > > > 00 [VGA controller]).
> > > > > > > > >
> > > > > > > > > No kernel driver is seen in lsmod. Please refer to lsmod.txt
> > > > > > > > >
> > > > > > > > > When I tried to load the kernel module by executing "modprobe 
> > > > > > > > > i915",
> > > > > > > > > it complains "no such device".
> > > > > > > > >
> > > > > > > > > ERROR: could not insert 'i915': No such device
> > > > > > > > >
> > > > > > > > > So is my Intel HD Graphics 4600 VGA Passthrough to Debian 
> > > > > > > > > 7.1.0 amd64
> > > > > > > > > HVM domU considered successful since the i915 driver cannot 
> > > > > > > > > be loaded?
> > > > > > > > > Thank you very much.
> > > > > > > > If you have a driver in dom0 claiming the device (other than 
> > > > > > > > the xen-pciback
> > > > > > > > driver), you cannot pass through that device. If you do lspci 
> > > > > > > > -ccc on F19
> > > > > > > > and you see the driver in use for that device being something 
> > > > > > > > other than
> > > > > > > > xen-pciback, that would explain why you can't pass it through.
> > > > > > > >
> > > > > > > > Also, did you first do xl pci-assignable-add for that device? 
> > > > > > > > This attempts
> > > > > > > > to detach the device from it's current driver but doesn't 
> > > > > > > > always work
> > > > > > > > especially for GPUs. The only solution is blacklist the driver 
> > > > > > > > for the
> > > > > > > > device in dom0. The downside is that you cannot run a GUI in 
> > > > > > > > dom0 on that
> > > > > > > > device.
> > > > > > > I cannot start Fedora 19 HVM domU with VGA passthrough at all. 
> > > > > > > Could
> > > > > > > you advise me on the workaround?
> > > > > > >
> > > > > > > As for the Intel HD Graphics (i915) driver, I have it 
> > > > > > > blacklisted in
> > > > > > > /etc/modprobe.d/blacklist.conf already. Please refer to 
> > > > > > > attached
> > > > > > > blacklist.conf.
> > > > > > Have you confirm that no other driver is bound to the device in 
> > > > > > lspci -vvv?
> > > > > > Also what version of Xen are you running on each of the distros, 
> > > > > > and which
> > > > > > dom0 kernel?
> > > > > I have checked "lsmod | grep i915" and the command doesn't return
> > > > > anything, which means the kernel module i915 is not loaded in 
> > > > > dom0.
> > > > Check lspci -vvv,find the device in the output and look for the 
> > > > lines that say:
> > > > Kernel driver in use:
> > > > Kernel modules:
[...]

> > > I have checked lspci -vvv in Ubuntu 13.04 dom0 and the Kernel 
> > > driver
> > > in use is pciback for Intel HD Graphics 4600 IGD.
> > >
> > > As for Fedora 19 HVM domU, I don't know because I cannot start it.
> > Starting is not required to do this. Do it before starting the domU.
> Sorry, I don't understand what you're trying to say.
On F19, don't worry about starting the domU. In dom0, do lspci -vvv,
find the Intel graphics device in the output and find what kernel
driver / module are bound to it, if any. You can only pass through
a PCI device that is connected to the xen pciback driver, and even
then often only if no other driver had connected to the device first
since that might leave it in an unknown state.

Gordan

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