Re: [Xen-devel] [Xen-users] VGA passthough still not working

["Likarpenkov Alexander" <al@xxxxxxxxxxxxxxx>]

??>> I say that ATI produces the same effect. I do not see anything until
??>> the
??>> welcome screen and only when gfx_passthru = 0. If gfx_passthru = 1 -
??>> qemu
??>> shell on vnc console and freezed domU :(

DM> You won't be able to passthrough an ATI card with the BIOS for multiple
DM> reasons.  First, the ati bios keeps a copy of the pci config space, so
DM> certain values need to be modified for it to work properly with the
DM> guest addresses.  The most recent experimental patch for this was from
DM> december 2010:
DM> http://lists.xen.org/archives/html/xen-devel/2010-12/msg00705.html
DM> I can confirmm i had limited success with this.


DM> However, this patch was based on xen-unstable before the 4.1-rc's came
DM> out.  You can try building an older version of xen (in that thread, i
DM> mentioned the specific C/S i used in testing) and applying the patch or
DM> forward porting the patch to the current xen/qemu-xen.

In fact of the matter is that it tested an older version of Xen, and I read 
about this in the beginning of its work with Xen (although there was a 
version 4.0.1rc3.) Out of my last comment^ 4.1.2 works more stable than 
4.0.2 4.0.1rc3
And how to roll the old patch to newer versions of xen?

DM> Also, i believe you said the card you're trying to pass through is not
DM> the primary card in your host system.  If that's the case, don't use
DM> gfx_passthru or expect to get the video bios working.  The 'primary'
DM> video adapter owns certain io ports and memory areas that are consitent
DM> from machine to machine.  Also, the system will copy the vbios from the
DM> card to a location in memory (0xc0000) so it can execute at boot time.

DM> Xen's gfx_passthru code depends on all of these factors.  As the code
DM> stands, if you use gfx_passthru on a secondary card, it will still copy
DM> the vbios from the primary card (as it simply reads memory from
DM> 0xc0000), and directly map io ports and low memory areas to those used
DM> by the primary card in the host system.  In this case the guest will
DM> almost certainly never get past executing ROMBIOS, and the host may or
DM> may not lock up or experience 'issues'.

I use both. When the primary adapter is the one on which you want to run 
gfx_passthru - there remains the possibility to control the system through 
the console, not ssh. There is the following question: if I have a primary 
device that the video card, you want to passing, I need to do it pciback and 
add config DomU pci = ['02: 00.0 '], where '02: 00.0' - is the primary 
graphics card or no???


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