Re: [Xen-users] Have you ever met this behavior with IGD passthrough?

[Andrew Bobulsky <rulerof@xxxxxxxxx>]

On Fri, Jul 26, 2013 at 3:04 AM, G.R. <firemeteor@xxxxxxxxxxxxxxxxxxxxx> wrote:
> Hi guys,
>
> I know that both of you are playing with IGD passthrough. So I would
> like to check with you if I'm the only one that saw this behavior.
> In my system, the panel becomes flickering rapidly with different
> colors after domU starts. This lasts until the guest loads gfx driver.
> There is a workaround by loading the VGA module in GRUB2, which
> greatly shorten the time it flickers. But with a natively installed
> windows guest, the flickering lasts until the OS get the login screen
> prepared. But if the windows is not properly shutdown and the system
> enters the repairing screen in next boot, you can simply see nothing
> in this case.
>
> This is not show-stopper but is quite annoying. But to my surprise, it
> seems that nobody mentions this behavior in blogs / mail-lists. What's
> your case then?
>
> PS: Previously (e.g. xen 4.2.x), this flickering only happens happen
> on a second guest boot and later-on (Per host reboot). I just upgraded
> to xen 4.3.0, and haven't got chance to see if this behavior has
> changed.
>
> Thanks,
> Timothy


Hello Timothy,

This is actually one of the more infuriating problems with secondary
passthrough...  Windows Startup Repair will just sit there forever.

To disable it, run the following command in your Windows DomU from an
elevated command prompt:

> bcdedit /set {default} recoveryenabled No

That will at least prevent your guest boot from getting hijacked.

You said something about being able to fix that flickering problem by
loading a GRUB2 module.   Does this module allow you to see bootloader
output on a non-primary passedthrough GPU if you chainload the Windows
Boot Manager from it?  That would be a pretty neat workaround!

Cheers,
Andrew Bobulsky

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