I have a system (Biostar IDEQ210M mini-pc with a VIA chipset) which will
not reboot unless a keyboard is plugged in to it.  I have tried all
combinations of the kernel "reboot=x,y" flags to no avail.  Rebooting by
any method will leave the system in a wedged state (at the "Restarting
system" message).

I finally tracked the problem down to the machine's refusal to fully reboot
unless the keyboard controller status register had bit 2 set.  This is the
"System flag" which when set, indicates successful completion of the
keyboard controller self-test (Basic Assurance Test, BAT).

I suppose that something is trying to protect against sporadic reboots
unless the keyboard controller is in a good state (a keyboard is present),
but I need this machine to be headless.

I found that setting the system flag (via the command byte) before giving
the "pulse reset line" command will allow the reboot to proceed.  The patch
is simple, and I think it should be fine for everybody whether they have
this type of machine or not.  This affects the "hard" reboot (as done when
the kernel boot flags "reboot=c,h" are used).
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>