[coreboot] SeaBIOS, serial output, and grub

Ward Vandewege ward at gnu.org
Wed Apr 29 21:10:23 CEST 2009

I've been experimenting with SeaBIOS, and I like what I'm seeing a lot. Great
work Kevin!

I think I found one bug, and I have a feature request.

Feature request: I'd really like a serial console for SeaBIOS. I 'd like
serial to just mirror the VGA console so that either could be used for
viewing and input. Right now, it seems only sending debug output to the
console is supported.

Bug: I have grub configured to pause 5 seconds while giving the user to
select either serial or VGA console for input. This is done with these lines
in menu.lst:

  serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
  terminal --timeout=5 serial console

This does not appear to go over well. The symptoms I see are:

a) the 'Press any key to continue' is only printed on the VGA console, not on
b) it takes way more than 1 second between the 'Press any key to continue'
lines - presumably because writing to serial is somehow failing
c) while this is happening, keyboard nor serial console input works

If I press enough keys before I get to grub and/or during this serial/console
detection, I can sometimes get it to show the menu on the VGA console (it
defaults to serial). If I get to that point, the keyboard usually works just

Also, the keyboard works fine before I get to grub, but it's hard to catch
the F12 keypress as everything goes pretty fast.

I've tried with and without CONFIG_DEBUG_SERIAL set in src/config.h. It does
not seem to make a difference. CONFIG_SERIAL is set to 1.



Ward Vandewege <ward at fsf.org>
Free Software Foundation - Senior Systems Administrator

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