[poky] Serial console unusable with poky-image-sdk

[Richard Purdie]

On Fri, 2011-01-28 at 09:56 -0700, Gary Thomas wrote:
> On 01/28/2011 09:51 AM, Wolfgang Denk wrote:
> > Dear Darren Hart,
> >
> > In message<4D42F269.1080005 at linux.intel.com>  you wrote:
> >>
> >> The serial console would show all the output of the boot process and
> >> then present a getty. It would accept my login and my password, but as
> >> soon as I was logged in, things went weird. Only every Nth character I
> >> typed made it to the console, where N was somewhere between 2 and 30.
> >
> > Indeed. And the reason for this behaviour is that you have two
> > processes reading from the console, so it depends on the scheduling
> > which of hem receives which characters.
> >
> >> I believe this had something to do with the automatic consoles the
> >> kernel will setup based on the console= parameters. By default, the last
> >
> > No, it does not.  You can test it by shutting down X11 (try:
> > "/etc/init.d/xserver-nodm stop"); this will also terminate the
> > dbus-launch process, and your login shell immediately works fine.
> >
> > Or try out the patch I posted.
> >
> >> What I haven't been able to explain yet is why just omitting the getty
> >> from the tty doesn't result in console on the serial port due to the
> >> kernel's automatic console thing. So clearly there are some gaps in my
> >> explanation here, but please try this approach and let me know what your
> >> results are. Based on that, we can dig a bit more and figure out how to
> >> best setup the console= directives on the default images.
> >
> > THere is no problem with the console= settings.  It's two processes
> > reading from a single input stream. This can never work.  Try it ut if
> > you don't believe me.
> 
> Wolfgang has it spot-on - both the console login and dbus are
> fighting over the console device.
> 
> I've been using the equivalent of this patch for months and it
> solves the problem just fine.  (Sorry I didn't report it, it
> wasn't high on my list)

FWIW I've now merged Wolfgang's patch into master.

If there are issues like this please do tell us about them as its good
to get them fixed.

Cheers,

Richard