CentOS - Mar 2013 - Ctrl-Alt-F? bindings broken under xen 3.0.3-142.el5_9.1 / 2.6.18-348.1.1.el5xen?

I am not sure what I did, but for some reason Ctrl-Alt-F? bindings are
broken on 64-bit xen desktop machine (but not on my laptop (32-bit, no
xen)).  Both machines are (mostly) up-to-date and running CentOS 5.9. 
I rarely hop to different Virtual Consoles (eg Ctrl-Alt-F1 ...
Ctrl-Alt-F7), but today I wanted to go to the main console to watch
some kernel verbage (I was checking something with hot-swap SATA disk).
I discovered that I could not switch back to my X11 session
(Ctrl-Alt-F7)! I did some googling, but did not find anything.  So far
as I can tell, I can switch to one of the other VT (Ctrl-Alt-Fn) *from*
VT7 (my X11 session), but cannot then switch to any other VT from
there, using the Ctrl-Alt-F? key bindings. The chvt command works, but
the keybindings don't.  It is most strange.  I know this used to work
(and still does work just fine on my laptop, running much the same
system, including the same X11 configuration, with the same desktop
setup (plain fvwm in MWM compatibity mode, same keybindings, etc.). 
Other than different video cards (and thus different X11 drivers) and
32-bit vs 64-bit and with xen virtualization on the 64-bit desktop box,
the system setups are virtually identical.

-- 
Robert Heller             -- 978-544-6933 / heller at deepsoft.com
Deepwoods Software        -- http://www.deepsoft.com/
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OK, some more information:

I rebooted to a non-xen kernel (2.6.18-348.1.1.el5), and the problem
remains, so it is not xen or a xen kernel issue.  The machine has an AMD
64-bit processor (AMD Sempron(tm) Processor LE-1300), if that makes any
difference.  I have a LD450 keyboard (DEC VT220 flavored ps2 keyboard).
The keyboard does work: the X server properly intercepts Ctrl-Alt-Fn and
does a proper chvt call.  The *kernel* itself is not handling
Ctrl-Alt-Fn.  (It is handling Ctrl-Alt-Delete, but I suspect that is
something completely different.)

My 32-bit laptop, running kernel 2.6.18-348.1.1.el5 is working just fine
-- the kernel there is properly handling Ctrl-Alt-Fn and switches
between consoles without problems.

Oh, both machines boot to runlevel 3 and I use startx to fire up X (I
loath graphical logins).

At Wed, 20 Mar 2013 13:26:14 -0400 CentOS mailing list <centos at
centos.org> wrote:
> 
> I am not sure what I did, but for some reason Ctrl-Alt-F? bindings are
> broken on 64-bit xen desktop machine (but not on my laptop (32-bit, no
> xen)).  Both machines are (mostly) up-to-date and running CentOS 5.9. 
> I rarely hop to different Virtual Consoles (eg Ctrl-Alt-F1 ...
> Ctrl-Alt-F7), but today I wanted to go to the main console to watch
> some kernel verbage (I was checking something with hot-swap SATA disk).
> I discovered that I could not switch back to my X11 session
> (Ctrl-Alt-F7)! I did some googling, but did not find anything.  So far
> as I can tell, I can switch to one of the other VT (Ctrl-Alt-Fn) *from*
> VT7 (my X11 session), but cannot then switch to any other VT from
> there, using the Ctrl-Alt-F? key bindings. The chvt command works, but
> the keybindings don't.  It is most strange.  I know this used to work
> (and still does work just fine on my laptop, running much the same
> system, including the same X11 configuration, with the same desktop
> setup (plain fvwm in MWM compatibity mode, same keybindings, etc.). 
> Other than different video cards (and thus different X11 drivers) and
> 32-bit vs 64-bit and with xen virtualization on the 64-bit desktop box,
> the system setups are virtually identical.
> 
-- 
Robert Heller             -- 978-544-6933 / heller at deepsoft.com
Deepwoods Software        -- http://www.deepsoft.com/
()  ascii ribbon campaign -- against html e-mail
/\  www.asciiribbon.org   -- against proprietary attachments