[support-gang] using usb2vga with 11.2.0 and 10.1.3

Daniel Drake dsd at laptop.org
Sun Jun 19 08:48:58 EDT 2011

On 19 June 2011 13:14, Kevin Gordon <kgordon420 at gmail.com> wrote:
> Since it seems to never work on any build, if you like, I can concentrate on
> just os23 on multiple XO 1.0 machines on multiple USB ports and see if there
> are any differences in where it halts, even if I've previously plugged it in
> after boot or not.  I've had it get to the 3rd dot before hanging on a
> couple of occasions, and I think that's the time I see the 'Starting Cronds'
> on the console .  So, if I have a more directed rather than shotgun plan,
> perhaps I can be more helpful.

That's interesting, thanks for the extensive testing.
On the ticket I suggested some next steps for debugging.

The 3rd one you can do without a serial console. "See if you can
reproduce it as follows: move the sisusbvga.ko file to somewhere where
modprobe can't find it, boot the system and stop X. Then run a loop at
the shell of insmod;rmmod, see if that makes it possible to reproduce
the hang quickly"

More specific instructions for this:

Boot without USBVGA connector attached. Go to a root terminal and move
sisusbvga.ko to /root:
# mv /lib/modules/*/kernel/drivers/usb/misc/sisusbvga/sisusbvga.ko /root

Power off the system, connect USBVGA, boot. It should boot
successfully, but without any VGA output. Press ctrl+alt+f2 to get to
a root terminal, and stop X/sugar with:
# stop prefdm

Now load the sisusbvga driver manually and see if it hangs:
# insmod /root/sisusbvga.ko

Wait a few seconds, see if the system is hung or if you can still type
on the console.

If you can still type, unload the module:
# rmmod sisusbvga

and now try loading/unloading a few more times with a few seconds
pause between each step.
# insmod /root/sisusbvga.ko
# rmmod sisusbvga
# insmod /root/sisusbvga.ko
# rmmod sisusbvga

The idea is to find out whether the system hang is caused by the
loading of sisusbvga. It might not hang first time, may require a few
attempts, hence the repeated loading.


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