Re: [Xen-devel] Memory mapping for PEG/PCIe Graphics Passthrough to <any> DomU

[Alexia Benington <alexbenington@xxxxxxxxx>]

Hi,

I've been trying to get this to work for some months, albeit not
full-time. I concur that many would like to see it working. Some have
posted that they managed to get it to work correctly, however, they
almost always never reply to queries on how they got it to work, or
their observations.

I did manage to get rid of the yellow exclamation mark. You'll need to
disable the emulated VGA bios, pretty much as described here
http://lists.xensource.com/archives/html/xen-devel/2008-12/msg00474.html.

Even after doing so, some of the registers are not directly passed
through. See 
http://lists.xensource.com/archives/html/xen-devel/2009-02/msg01131.html.
I'm not sure if that may affect anything.

I've experimented with an Intel DQ45CB, nVidia Quadro NVS 290, nVidia
GF9500, ATI Radion HD 2600XT. The best results I get are when using
the onboard igfx as the primary, which is also being passed through.

There is also a writeup which you might want to take a look
http://staff.science.uva.nl/~delaat/sne-2008-2009/p22/report.pdf.

I'm also trying to get DomU's output to the display.

-Alex

2009/3/30 Tim Moore <timothy.moore@xxxxxxxxxxx>:
> Hi
>
>
>
> I have been testing xen-unstable.hg (29/03/09) over the past few days ..
> trying to enable passthrough for VGA.
>
>
>
> I am using Debian 5.0 (lenny) x64 and compiling from source each time. Tried
> both linux-2.6.18.8 and linux-2.6.27.5 from Xenbits …
>
>
>
> Hardware is Nvidia Geforce 8800 512mb GTS PCIe on Intel X58 (ASUS P6T
> Deluxe) with Core i7 920 CPU.
>
> (had to hack the xen/drviers/pci/passthrough/vtd/dmar.c (line 388) and
> remove the DMAR bail because of bad RMRR tables.
>
> I also have ATI X300 PCIe for Dom0 Console.
>
>
>
> Using Xen parameter: iommu=passthrough,pv
>
> Using Dom) parameter: pciback.hide=(‘…’)
>
>
>
> I compiled pciback as embedded in the kernel and I have tried many different
> scenarios:
>
>
>
> 1) Nvidia Primary (hidden with pciback.hide= kernel param) (no ATI card
> installed)
>
> 2) ATI Primary, with Nvidia hidden (with pciback.hide= kernel param)
>
> 3) all scenarios with pciback as module and using echo devn >
> /sys/bus/pci/drivers/pciback/new_slot and bind
>
>
>
> In all scenarios I can successfully see the correct PCI device in the
> DomU(s), I have tried primarily Windows XP 32bit SP3 and also:
> linux-2.6.18.8 and linux-2.6.27.5 PV and non PV kernels as DomU and
> (although I didn’t load a driver) the lspci –vvv showed the devices.
>
>
>
> Now, I progressed to installing drivers under the Win32 DomU against the
> Nvidia card, windows correctly identified the device and installed the
> driver! (latest from nvidia.com). As we all know – Windows wanted a reboot-
> beforehand a quick check of the device and it has a Yellow exclamation
> indicating reboot required and resources unavailable.
>
> Reboot and XP starts up … BSOD .. nv4 driver fails .. L
>
>
>
> Tried with the ATI X300 Primary (no NVidia connected) and went through the
> same steps. Windows XP now boots without crash although the ATI device still
> shows a yellow exclamation and insufficient resources.
>
>
>
> To summarise, pciback functions as expected for PCIe in Dom0 and DomU sees
> the device. All tools work fine (xm pci-attach / pci-detach / pci-list) and
> devid show and are managed correctly.
>
>
>
> I have read all that there is on this subject and have come to the
> conclusion that this is a problem with qemu-dm and the memory mapping for
> the new Video device, the Cirrus or stdvga card is always present which I
> believe may be causing the problem. I have tried nographics=1 but qemu-dm
> still maps the Video BIOS.
>
>
>
> Then I noticed that qemu-dm has the new options for “-vga none” .. so I
> built a wrapper script for qemu-dm to launch with this param. Unfortuntately
> the DomU doesn’t startup and the qemu log does not show any mention of the
> Video memory ! so I believe the switch works, but the DomU then fails to
> boot L
>
>
>
> To solve this and make it usable I think some development of qemu with
> regards to the Cirrus VGA and memory management when using more than 1 vga
> controller is necessary in order to remap the Cirrus or secondary vga
> adapters in memory correctly. (its also difficult to configure a Windows
> machine for a second vga when the primary is disabled lol.)
>
>
>
> Also, I have run strace using a qemu-dm wrapper (very verbose) and analysed
> the results –nothing seems obvious, but i`m not an expert by far ….
>
>
>
> Windows has been able to support multiple VGA cards for a long time; I
> assume that MS is remapping these somehow?
>
>
>
> I have read in 2 different places that this has worked for others before
> (without the legacy patch for igfx) and with xen-unstable.hg .. why does it
> not work for me ?
>
>
>
> Any help / direction to further debug would be helpful .. I think many
> people would like to get this one working once and for all!
>
>
>
> Tim
>
> _______________________________________________
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> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>
>

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