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Re: [Xen-users] Primary VGA Passthrough Status

Just found it claims to be supported on the spec list of the 2000 cards, but I am curious if everything still works normally on the converted Quadros.


On Wed, Oct 9, 2013 at 9:36 AM, David Erickson <halcyon1981@xxxxxxxxx> wrote:
Thanks Gordan-
I took a look, none of the 2000s seem to have native HDMI out.  This is actually an important point to me, when you flash from GeForce -> Quadro (or are using a native Quadro like the 2k), is there also a functioning pass through HDMI audio device?  And in the case of the Quadro 2000, would I be able to get video and audio out of the displayport and convert it to HDMI?

On Wed, Oct 9, 2013 at 1:54 AM, Gordan Bobic <gordan@xxxxxxxxxx> wrote:
If you are after a low end card, you might as well just
buy a genuine Quadro 2000. It's single-slot, powered from
the slot (no auxiliary power required), should be ample
for a HTPC, and will "just work". And they are cheap
enough on ebay that it's not worth trying to cut a

On Tue, 8 Oct 2013 17:49:35 -0700, David Erickson <halcyon1981@xxxxxxxxx> wrote:
David or Gordon have you tried this on lower end cards like a GT
640?  (Maybe there isn't a Quadro even close to flash it to).  These
cards are major overkill for a non-gaming HTPC.


On Tue, Oct 8, 2013 at 3:22 PM, David TECHER  wrote:

Gordan is right.

In the past patches maintenance for NVIDIA was a real pain. That's the
reason why I stopped to maintain those patches in February, 2013.

1) Soft-moding a GTX 480 to a Quadro 6000 aims at unlocking the
expected feature on the card


I tested on two GTX 480 cards and it works very well. Just a bios to
edit/update. Check the checksum and updates straps bits

2) Hard-moding a GTX 680 to a 1/2 GRID K2 works very well too. I
tested it on a Gigabyte GV-N680OC-2GD...it works like a charm

3) Hard-moding a GTX 670 to a 1/2 GRID K2 works very well too. I
tested it on the MSI N670GTX-PM2D2GD5/OC...it works like a charm (just
a few resistors to remove)


This card has a similar PCB than Asus card provided/tested on the
eevblog forum


  DE : David Erickson
 À : Gordan Bobic
 CC : "xen-users@xxxxxxxxxxxxx [7]"
 ENVOYÉ LE : Mardi 8 octobre 2013 20h56
 OBJET : Re: [Xen-users] Primary VGA Passthrough Status

On Tue, Oct 8, 2013 at 9:43 AM, Gordan Bobic  wrote:
 On Tue, 8 Oct 2013 09:20:51 -0700, David Erickson  wrote:

  On Tue, Oct 8, 2013 at 5:42 AM, Gordan Bobic  wrote:
  On Tue, 8 Oct 2013 00:04:33 -0700, David Erickson  wrote:

   On Mon, Oct 7, 2013 at 11:29 PM, Gordan Bobic  wrote:

  On 10/07/2013 09:33 PM, David Erickson wrote:
    Hi All-
   Is it possible yet to pass through a ATI or Nvidia GPU as the
   VGA card to a Win 7/8 VM, and have it fully functional there

   Why exactly do you need the card to be primary in domU? IME this
  doesn't gain you anything other than being able to see the BIOS
  screen and boot animation on the external monitor (which in itself
  isn't worth the extra effort).

  Primarily it is for htpc functionality like Blu-ray playback
  and Digital Cablecard based playback using devices like a HDHR
  Prime.  I believe the code that tests for playready (or
  compatibility always looks at the primary video card and finds it
  totally missing any of these features and refuses to play back
  properly.  I need to verify that having a passed through card as
  primary actually solves these issues, but I think it is a
  hunch (unless anyone else has already tried this and proved it

  I never used it so cannot comment on it. David Techer maintains a
  patch set for Nvidia cards that include primary passthrough
  The one in particular you will need is the one that gives the VBIOS
  loading supprot in domU. Between that and a GTX480 modified to a
  Quadro 6000 (VBIOS editing required) you _might_ just be able
  to get it to work. I never tried primary passthrough since
  passthrough has always worked for all of my requirements.

     without crashing the guest or the host during operation or when
   resetting the guest?

   It works fine with Nvidia Quadro cards (real or modified
  provided your hardware works properly (e.g. no dodgy PCI bridges
  as Nvidia NF200) bypassing the IOMMU). The latter is, it turns out,
  quite rare - an awful lot of hardware seems to have IOMMU support
  broken to some extent.

  Is there something special in the bios/firmware that is enabled
  converting these to Quadros?

  You have to modify the strap bits. This can be done with a BIOS
  on cards up to GTX480, or with some soldering on a GTX680 (you will
  need good eyes, steady hands, high quality soldering paste and some
  pro grade soldering kit (hot air or oven - you might be able to
  get away with a really tiny soldering tip, but bear in mind that
  you will be looking at soldering both ends of a resistor that is
  long, without shorting it out). If you want the easy option, go
  for a GTX480 and BIOS mod it (or a GTX470 -> Quadro 5000 or a
  GTS450 (make sure you get a 1GB GDDR5 one) -> Quadro 2000 I have
  used all of the above extensively without any issues).

 Thanks Gordon, I probably wasn't clear in my question, but when you
 convert it from a standard Geforce => Quadro, what is changing at the
 card level to make it more compatible with PCI Passthrough and Xen?

 GeForce drivers don't implement support for various quirks and
 side-effects of running in a VM. Quadro drivers do. You change the
 PCI ID of the card by modifying the straps. That makes the card get
 detected as a Quadro rather than a GeForce, and the Quadro driver
 deals with the quirkyness and side-effects of running in a VM (e.g.
 the fact that the physical BARs differ from the virtual BARs).

 The hardware between the GeForce and the Quadro is by and large
 the same. The reason for the modification is to convince the Quadro
 driver the card really is a Quadro and that you paid an extra pile
 of cash for the privilege of running it in VGA passthrough.

  Is it some feature of the new firmware that is being flashed to the

 No, it's a hack to facilitate the use a driver that can handle
 in a VM.

  And do Geforce cards just absolutely not work at all prior to
 being converted to Quadros?

 GeForce cards absolutely do not work with VGA passthrough without
 modifications; at least not without an additional, unsupported patch
 set which doesn't work for recent cards (4xx cards work, not sure
 about the more recent ones), recent drivers (more recent than
 and recent OS-es (more recent than XP).

 And unless your time really is worthless, getting a GeForce 4xx
 card and modifying it once with no other side effects is a lot less
 effort than maintaining your own build of Xen packages with the extra
 patches, even if they do work for your specific use-case.


Thanks that made it very clear, and I totally agree on the time point.

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