Most video drivers should not need to access the bios. Once the system
is up and running, the video bios has done its job. I'm not sure if
there are exceptions to this.
I believe you are referring more to the framebuffers, or video RAM. I
guess that depends on whether addresses are being hardcoded in the
driver. Will appreciate if there's anyone who can explain if there's
any address translation being done in the case of Vtd.
On another note, Jean's patch for the bios is only for the range from
C0000 - CAFFF. Typical video BIOS range is up to C7FFF. Is there any
reason for the smaller range? Is this range only specific to Intel?
- Alex
On Fri, May 1, 2009 at 4:01 PM, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
> 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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