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

[Gary Thomas]

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)

-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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