After an install through the experimental live CD from 20130122 over the serial console on a C8000 (64 bit kernel), the serial console ttyB0 got automatically added to /etc/inittab. That's great, but the documentation says that you have to add it yourself, which I did. Ended up with 2 gettys battling for the same serial console ;-( If I hadn't configured sshd before reboot, I would not have been able to login. Reproducible: Didn't try
the default serial console enable for various targets changes over time. the install docs should recommend you do it iff it hasn't already been added.
I grepped through the handbook code but found no references to ttyB0; the only reference I found to inittab says to uncomment serial consoles - is that the one you mean? http://www.gentoo.org/doc/en/handbook/handbook-hppa.xml?part=1&chap=9
Yes, ttyB0 is the standard serial console name given from the HP firmware.
Okay, changed paragraph to mention that uncommenting might be needed if it has not been done automatically yet. Committed to CVS, should show up on the site in an hour or so.