Re: [Gumstix-users] How to redirect /var/log messages to serial port?

[Steve S. <sa...@gm...>]

Dave,

Thanks!  Just had another failure, so I commented out those two lines.

The delays shouldn't be an issue, during normal operation the log file gets
a very short message once a minute.

This is an interesting problem.  I left "tail -f /var/log/messages" running
overnight because I didn't want to reboot the unit since it had been
operating perfectly all day.

It did fail overnight. What I saw in the serial output was the normal series
of time stamped once a minute log messages, and then a reboot at around
11pm.  The boot messages were normal, wifi networking started normally, and
the system picked up the current time from pool.ntp.org.  Then came the
normal login prompt.

Something bad must have happened afterward though, the serial connection was
non-functional (ie couldn't type anything at the login prompt) and the
network connection had been dropped (the yellow wifi led was off).
Obviously the "tail" command wasn't running, so I didn't get any further log
messages after the reboot.

Rebooting via power cycling restored the unit to normal operation.

So now to wait for the next failure and the post reboot messages . . .

Thanks again,

Steve




On 5/10/07, Dave Hylands <dhy...@gm...> wrote:
>
> Hi Steve,
>
> On 5/10/07, Steve Sakoman <sa...@gm...> wrote:
> > >I would keep "tail -f /var/log/messages" running on the serial console.
> >
> > I've had that running for the past few hours -- no crash yet so I'm not
> sure
> > if it will do the trick
> >
> > >"syslogd -n -m 0 -O /dev/console"
>
> Actually, if you comment out the syslogd and klogd lines from the
> /etc/inittab file, then all of the console messages will go to the
> serial console.
>
> Not only that, but they'll happen in realtime with no delay. So if the
> system crashes you won't be missing any messages.
>
> The disadvantage of doing this is that printk's which are excuted from
> within an ISR will actually add a considerable delay to the execution
> time of the ISR. printk messages bypass the serial fifo so if you
> write a 12 byte message, it will take 120 bit times to print.
>
> 120 / 115200 =1 msec of delay.
>
> With a well written driver this won't make any difference, but it will
> have a considerable impact on real-time performance, and will also
> dramatically change the timing of things.
>
> You can direct the console to a different serial port by adjusting the
> console= line passed in from u-boot.
>
> --
> Dave Hylands
> Vancouver, BC, Canada
> http://www.DaveHylands.com/
>
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