linux-kernel - Geode LX800 hanging at boot in vesa_store_edid() w/ CONFIG_FIRMWARE

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Date:	Tue, 4 Mar 2008 02:11:31 -0500
From:	"Andrew Paprocki" <andrew@...iboo.com>
To:	linux-kernel@...r.kernel.org
Cc:	"Jordan Crouse" <jordan.crouse@....com>
Subject: Geode LX800 hanging at boot in vesa_store_edid() w/ CONFIG_FIRMWARE_EDID=y

I have a LX800 board which hangs at boot time *only* if no monitor is
plugged into the VGA port. It hangs for about 20 minutes and then
continues booting.  If a monitor is plugged into the system while it
is hung, it recovers after a few minutes and continues booting.  I
added puts() debugging in the kernel main() and it is hanging in
vesa_store_edid() in the first asm() call:

        /* Note: The VBE DDC spec is different from the main VESA spec;
           we genuinely have to assume all registers are destroyed here. */

        asm("pushw %%es; movw %2,%%es; "INT10"; popw %%es"
            : "+a" (ax), "+b" (bx)
            :  "c" (cx), "D" (di)
            : "esi");

After waiting for a really long time, this int10 finishes and it
executes the second asm() call which returns right away.  I never
tried booting the system without a head, so I never noticed this
problem before.  Does this point to some kind of BIOS bug?  The system
boots fine when CONFIG_FIRMWARE_EDID is disabled (I'm not even sure if
it should have been enabled in the first place), but I want to make
sure the manufacturer is alerted if there is a BIOS problem.

Thanks,
-Andrew
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