Successfully verified with grml-small_sid_20100602.iso and bootoption 
console=ttyS0,57600n8 - works as expected. Closing this bugreport.

regards,
-mika-

Michael Prokop <mika@grml.org> has uploaded a package that may fix your bug.
Please test the package and inform the maintainer whether
version 0.9.10 of grml-autoconfig works as intended or not.

Thank you

The changelog is attached below

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Format: 1.8
Date: Tue, 01 Jun 2010 00:00:31 +0200
Source: grml-autoconfig
Binary: grml-autoconfig
Architecture: source all
Version: 0.9.10
Distribution: unstable
Urgency: low
Maintainer: Michael Prokop <mika@grml.org>
Changed-By: Michael Prokop <mika@grml.org>
Description: 
 grml-autoconfig - main bootup process of a Grml (based) system
Changes: 
 grml-autoconfig (0.9.10) unstable; urgency=low
 .
   * console/serial bootoption: allow manually specifying
     baude rate / speed settings. Thanks to Tonnerre Lombard
     and Marc Haber for reporting and special thanks to Marc
     for providing a system for debugging. [Testing: issue853]
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Files: 
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Fixed in Git, thanks for reporting and providing a test environment, Marc!

I just uploaded the Debian packages grml-etc and grml-autoconfig which should 
provide the fix, the upload will automatically set this bugreport to status 
"testing" and I'll make sure it works as expected before finally closing this 
bugreport.

thanks && regards,
-mika-

Hi,

in previous grml versions, grml tool the baud rate to configure the getty on
the serial console from the console= kernel command line item.

Recently, this has changed and tries to use some automatisms from getty, giving
it multiple baud rates on its command line. The getty man page says that a
Break could be used to change to the next baud rate.

This approach seems to be flawed in at least one of my settings, where the
target box has its serial console connected to a console server of unknown
manufacture which is in turn reachable via ssh, and which configuration I
cannot influence at all. grml serial console=ttyS0,57600n8 shows the boot
messages just fine up until the point when it says "Finished execution of main
grml startup" and the console turns to gibberish. This is the point where the
getty is started, and I guess that it comes up with a baud rate of 115200.

The getty man page suggests that a Break will cause the next baud rate to be
activated, but that doesn't seem to work through that Console server. Neither
Ctrl-@, nor Ctrl-C, nor ~B seem to have the desired effect.

I would suggest going back to the old setup, or at least to offer a possibility
to hard-specify the baud rate from the kernel command line in cases where the
new automatism misfires.

Greetings
Marc