[Xen-users] Using pciback to dynamically bind/unbind primary display driver: lost console, help

Ben Himberg
Sat, 29 Oct 2011 01:35:43 -0000

On Debain 3.1.0-rc7, Radeon 6870 and Xen 4.1 (no patches)

I used

echo -n 0000:01:00.0 > /sys/bus/pci/drivers/radeon/unbind
echo -n 0000:01:00.0 > /sys/bus/pci/drivers/pciback/new_slot
echo -n 0000:01:00.0 > /sys/bus/pci/drivers/pciback/bind

to move my primary display adapter (01:00.0) to pciback for domU use.  The
display, as expected, turned off.  I had enabled ssh to do this, and have
access to the system still.  I then used

echo -n 0000:01:00.0 > /sys/bus/pci/drivers/pciback/unbind
echo -n 0000:01:00.0 > /sys/bus/pci/drivers/radeon/bind

to pass it back to dom0 at which point the display turned back on.  Thinking
all was well, I made a script to do the above and executed it (with a sleep
of 10 seconds after the first bind) at which point I lost the display, as
expected, but it didn''t come back.  I then logged in through ssh and
find
that the radeon driver is bound to 01:00.0, but still no display.

I think I need to tell the console to output to the radeon driver, but I
have no idea how and a google search is proving fruitless.  Any help?
I''ve
also noticed that unbinding/binding the radeon driver is now (it wasn''t
initially) very slow to respond.

Thanks!