[coreboot] SeaBIOS, serial output, and grub

Myles Watson mylesgw at gmail.com
Fri May 1 04:40:16 CEST 2009

On Thu, Apr 30, 2009 at 8:26 PM, Kevin O'Connor <kevin at koconnor.net> wrote:
> On Thu, Apr 30, 2009 at 09:18:45PM -0400, Ward Vandewege wrote:
>> So - here's the problem with the sgabios approach. Unless I'm
>> misunderstanding how this works, using sgabios means that I'd have
>> to disable serial in any payload started from grub, as well?
> It seems to work fine under qemu.  In any case, a seabios
> implementation would have the same issues as sgabios - it would need
> to do exactly what sgabios does.
>> > > > >   serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
>> > > > >   terminal --timeout=5 serial console
> I've reproduced this problem under qemu.  If I boot
> qemu/coreboot/seabios/grub, then grub wont use the serial console.
> However, if I boot qemu/seabios/grub, then grub seems to work fine.
> The above is true regardless of whether SeaBIOS has serial port
> debugging on or off.  I guess coreboot is initialzing the serial port
> in some way that grub doesn't like.

I wonder if this is the same reason the serial console doesn't work
from Linux sometimes when I do Linux-as-Bootloader kernels in the ROM.
 I gave up on that method because it was too hard to debug without
serial output.


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