Re: graphics passthrough with VT-d

[Christian Tramnitz <chris.ace@gmx.net>]

Han, Weidong wrote:
>> - when creating the domU while I'm in text mode the dom0 stalls. It
>> doesn't lock up completely but the terminal and keyboard are frozen.
>> When I create the domU while dom0 is running X everything is fine.
> 
> When you passthrough secondary gfx to guest, it needs to claim the VGA cycle for assigned gfx to display guest booting progress. Then primary gfx doesn't own the VGA cycle to display text mode. In your case, pls use X in dom0 or use VNC to access dom0.
Actually I can see the text-mode boot process in domU on the passthrough 
secondary gfx card, it's just that the console stalls when running "xm 
create". This doesnt happen using an xterm, but I'm still able to see 
the text mode boot process (incl BOCHS Bios) on the secondary gfx card.

> 
>> - none of the HVM domU's have picked up the USB bus I tried to
>> passthrough (with keyboard and mouse attached). Not sure if I just
>> passed through the wrong bus or something else is broken
> 
> Firstly, make sure you assign the correct USB controllers attached keyboard and mouse to guest. BTW, I found USB controller assignment doesn't work well with pv-ops dom0

I'm using a xenclient kernel, but will simply passthrough *all* USB 
busses today.

> 
>> - after a domU is stopped it will still show the last image on the
>> passthrough gfx card (Knoppix desktop or Windows BSOD in my case)
> 
> It seems that the gfx card is not reset (FLR).

I thought the xenclient kernel has XCI already implemented but then 
again this might be limited to certain devices (Intel IGD).
It's no big deal anyway, just wanted to report it.

I'll continue to work on this patch-set instead of the just posted v2 to 
be able to passthrough the secondary gfx card and use pBAR-vBAR 1:1 mapping.


Thanks and best regards,
   Christian