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Re: [Xen-users] Difference between primary and secondary VGA pass through

  • To: Gordan Bobic <gordan@xxxxxxxxxx>
  • From: Daniel Shub <Daniel.Shub@xxxxxxxxxxxxxxxx>
  • Date: Fri, 2 May 2014 11:41:18 +0100
  • Accept-language: en-US, en-GB
  • Acceptlanguage: en-US, en-GB
  • Cc: "xen-users@xxxxxxxxxxxxx" <xen-users@xxxxxxxxxxxxx>
  • Delivery-date: Fri, 02 May 2014 10:42:29 +0000
  • List-id: Xen user discussion <xen-users.lists.xen.org>
  • Thread-index: Ac9l8wv4sivO344QQj2N7DSmhGQCHA==
  • Thread-topic: [Xen-users] Difference between primary and secondary VGA pass through

> On 2 May 2014, at 10:10, "Gordan Bobic" <gordan@xxxxxxxxxx> wrote:
>> On 2014-05-02 08:08, H. Sieger wrote:
>> Well, I've recently gave KVM a try and saw primary passthrough working
>> in my setup - that was until I installed the AMD driver in Windows
>> after which the guest didn't boot anymore/blue screen .
>> I believe primary passthrough can shorten the boot time of the guest,
>> but other than that I wouldn't break my head over that.
> Primary passthrough re-POSTs and initializes the GPU via the BIOS.
> That means you get to see the BIOS POST and OS loading screen on
> the physical rather than emulated GPU. Other than that there is no
> difference.
> The reason why primary passthrough was of interest recently was
> because ATI cards/drivers didn't handle rebooting domU gracefully,
> and re-POST-ing the card via the BIOS was a way of getting card
> back into a usable state without be driver choking on it in various
> ways. Now that the slot-level reset is being implemented, it makes
> for a simpler, more generic way to reset the card, which I guess
> takes some of the pressure for the need for primary passthrough
> for ATI cards.
> Nvidia binary drivers handle the card initialization gracefully
> (provided the card's device ID is in the expensive
> Quadro/Tesla/Grid white-list - hence why a lot of us have been
> modifying various GeForce cards into equivalent Quadros) whatever
> state it was left in, so this was never an issue for those.
> Gordan
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> http://lists.xen.org/xen-users

Do the open source Linux ATI/Radeon drivers support FLR? When I pass my ATI 
card as a secondary device to a Linux DomU I can only get it to work with the 
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