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Re[3]: [Xen-devel] Memory mapping for PEG/PCIe Graphics Passthrough to <

For what i understand of it, the video drivers (linux or windows alike)
expect the videobios to be in a hardcoded region, but cannot access it,
even with vt-d/iommu.

Is there a way to map regions from dom0 to domU (same or different address
?)

I haven't been able to seriously try it because of, guess what .. bad RMRR
tables. Currently waiting for a response of ASUS and AMI on this issue.


There is also a small thread on LKML about vga passthrough issues
http://lkml.indiana.edu/hypermail/linux/kernel/0904.3/01787.html

--
Sander



Hello Alexia,

Monday, March 30, 2009, 5:47:05 PM, you wrote:

> Hi Tim,

> It depends on your definition of success. If it helps, I've attached a
> screenshot of DomU's device manager. Dom0 will, obviously, lose access
> to the display, when the gfx is handed to pciback. I'll be glad to
> describe further if you require.

> With nVidia Quadro, the driver sits in an idling loop. According to
> the bugcheck error code, it's waiting for some kind of response from
> the gfx. I suppose this reflects Jean's point that some drivers are
> not very compatible.

> I was mostly trying Jean's patch, which he released sometime last
> year, into Xen unstable. I'm also curious how some have mentioned that
> they were able to get vga passthrough to work correctly without
> applying the patch. It might mostly work, but you'll still get the
> emulated VGA in DomU.

> -Alex

> 2009/3/30 Tim Moore <timothy.moore@xxxxxxxxxxx>:
>> Hi Alex,
>>
>>
>>
>> When you say you had success with the onboard igfx, how much success? Have
>> you ever had a passthrough VGA display from a DomU ?
>>
>>
>>
>> I have also seen the write-up too although a lot of work has been done on
>> the VT-d support lately and I`m hoping to raise this again on the developer
>> list and start to document some of the problems/issues so as we can find a
>> way do solve it !
>>
>>
>>
>> Thanks for the reply! It still leaves this issue unsolved though ;(
>>
>>
>>
>> Tim
>>
>>
>>
>> ________________________________
>>
>> Subject: Re: [Xen-devel] Memory mapping for PEG/PCIe Graphics Passthrough to
>>
>>         <any> DomU
>>
>> From: Alexia Benington <alexbenington@xxxxxxxxx>
>>
>> To: Tim Moore <timothy.moore@xxxxxxxxxxx>
>>
>> Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
>>
>>
>>
>> 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/msg=
>>
>> 01131.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. Tr=
>>
>> ied
>>
>>> both linux-2.6.18.8 and linux-2.6.27.5 from Xenbits =85
>>
>>>
>>
>>>
>>
>>>
>>
>>> 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=3Dpassthrough,pv
>>
>>>
>>
>>> Using Dom) parameter: pciback.hide=3D(=91=85=92)
>>
>>>
>>
>>>
>>
>>>
>>
>>> I compiled pciback as embedded in the kernel and I have tried many differ=
>>
>> ent
>>
>>> scenarios:
>>
>>>
>>
>>>
>>
>>>
>>
>>> 1) Nvidia Primary (hidden with pciback.hide=3D kernel param) (no ATI card
>>
>>> installed)
>>
>>>
>>
>>> 2) ATI Primary, with Nvidia hidden (with pciback.hide=3D 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=92t load a driver) the lspci =96vvv 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 =96 Windows wanted a reb=
>>
>> oot-
>>
>>> beforehand a quick check of the device and it has a Yellow exclamation
>>
>>> indicating reboot required and resources unavailable.
>>
>>>
>>
>>> Reboot and XP starts up =85 BSOD .. nv4 driver fails .. L
>>
>>>
>>
>>>
>>
>>>
>>
>>> Tried with the ATI X300 Primary (no NVidia connected) and went through th=
>>
>> e
>>
>>> same steps. Windows XP now boots without crash although the ATI device st=
>>
>> ill
>>
>>> shows a yellow exclamation and insufficient resources.
>>
>>>
>>
>>>
>>
>>>
>>
>>> To summarise, pciback functions as expected for PCIe in Dom0 and DomU see=
>>
>> s
>>
>>> the device. All tools work fine (xm pci-attach / pci-detach / pci-list) a=
>>
>> nd
>>
>>> 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=3D1 but qemu-=
>>
>> dm
>>
>>> still maps the Video BIOS.
>>
>>>
>>
>>>
>>
>>>
>>
>>> Then I noticed that qemu-dm has the new options for =93-vga none=94 .. so=
>>
>>  I
>>
>>> built a wrapper script for qemu-dm to launch with this param. Unfortuntat=
>>
>> ely
>>
>>> the DomU doesn=92t 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 vg=
>>
>> a
>>
>>> 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 analys=
>>
>> ed
>>
>>> the results =96nothing seems obvious, but i`m not an expert by far =85.
>>
>>>
>>
>>>
>>
>>>
>>
>>> 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
>>
>>>
>>
>>> _______________________________________________
>>
>>> Xen-devel mailing list
>>
>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>
>>> http://lists.xensource.com/xen-devel
>>
>>>
>>
>>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel
>>
>>



-- 
Best regards,
 Sander                            mailto:linux@xxxxxxxxxxxxxx


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