Re: [Xen-users] Cannot make VGA Passthrough with Xen 4.4.1

[Carl Schneider <carl.schneider+mailinglists@xxxxxx>]

Am 19.09.2016 um 20:43 schrieb Peter Milesson:
> On 2016-09-19 20:05, Manuel R. Campos wrote:
>> Hello to everybody,
>>
>> I have in my system this Xen version, I decided to use the one from
>> repos. Right now I'm using a Debian 8 (Kernel 4.1.21) with an
>> i7-4700EQ (I can use Vt-d and is enabled by dmesg) with 16 GB of RAM.
>> Manuel R. Campos Roldán
>>
> Hi Manuel,
> 
> Have you got a working IOMMU? If not, forget it.


Hi all,

@Milesson:
he already said that VT-d shows up in the dmesg - so that should be fine
(his CPU supports it, following
http://ark.intel.com/products/75469/Intel-Core-i7-4700EQ-Processor-6M-Cache-up-to-3_40-GHz).


@Manuel:
It would be nice if you could provide your kernel parameters, if you try
to bind on pciback there. So, how do you bind the device on pciback?
What GPU do you try to pass through?



My Radeon HD 7870 is pretty dangerous to pass through, because if any
driver touched it before passing it through, it will force the whole
system down (even when I just reboot the VM), pretty much as you
described it. Thus I need to bind it as soon as possible to pciback.

For that, I use the kernel parameter xen-pciback.hide=(XX.YY.Z) (change
to your PCI-address), which I added to GRUB_CMDLINE_LINUX under
/etc/default/grub (location _may_ vary).

Also note that it might be needed that any sound card that the GPU may
provide needs to be passed through, too. This is because they are
grouped together into one IOMMU-Group. There is a kernel patch to change
that behavior, but it may not work and may improve unforeseen instablities.


By the way, why does the config state 0a:00.0, but your command 00:02.0?
It sound like you try to attach an integrated GPU with the command, and
shoot away your output with that? Maybe provide the output of `lspci`, too?


Cheers,
CRT




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