Re: ttyS0 at wrong baudrate

On Mon, May 25, 2009 at 08:43:25AM +0200, Erazem Polutnik wrote:
> Dear all,
> I'm having PXA270 toradex board running kernel 2.6.23. kernel console is set
> to ttyS0,115200n8.
> In program we are also using ttyS0 and we initalize it to 4800,8,n,1.
> We output an NMEA stream on ttyS0 and everything is working ok.
> However, if PXA270 receive few characters from outer world at different
> baudrate than 4800,
> program crash with out of memory.

This is the classic case of "Doctor, Doctor, it hurts when I do X."
"Don't do X then."

Basically, don't do this - the system is doing precisely what you're
asking it to do, which is:

1. to have the kernel console on ttyS0
2. sysrq support to be enabled (so break + character invokes sysrq action)
3. lowered the baud rate of the console (which will halt the system while
   console output occurs)
4. receiving characters at a different baud rate which can be interpreted
   as break + character.

The golden rule here is: don't run the kernel console on the same port
that you're going to use for your application.

> [  322.240000] SysRq : Manual OOM execution
> [  322.250000] SysRq : HELP : loglevel0-8 reBoot tErm Full kIll saK showMem
> Nice showPc show-all-timers(Q) unRaw Sync showTasks Unmount
> shoW-blocked-tasks 

Two sysrq-invoked events.

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