Crash after successfully mounting root filesystem over NFS an d st arting busybox

Rob Landley rob at
Mon Dec 19 02:41:16 UTC 2005

On Sunday 18 December 2005 15:19, Gil Madar wrote:

> > You have no debug info so who knows what went wrong (you
> > could try to look
> > that up in if you're bored), but the 00000000
> > looks a bit like a
> > jump to a null pointer.
> According to the info in the log_buf and, the second exception
> and so on are generated
> during access to the MPC866 dual port ram, when trying to write to the
> serial port, which is ttyCPM0,

Translation: device driver issue.

> in my case. Till then there was no problem to write to the serial port.
> Is there anything I have to configure in busybox generated filesystem, as
> /etc/inittab, in order to
> use the console on my serial port - which is the MPC866's SMC1?

Kernel panics are generally not the fault of userspace.  With a few narrow 
exceptions (like PID 1 exiting or root doing something blatantly stupid like 
dd if=/dev/zero of=/dev/kmem), being _able_ to generate a kernel panic 
indicates a kernel bug.

What you have here is a device driver problem.  Busybox may be triggering it, 
but it's still a device driver problem.  Assuming a working driver is loaded, 
there's nothing special userspace should have to do to open a char device and 
write to it.  (Modulo possible ioctl calls like setting the serial port 

This is a problem with your kernel and its ability to talk to the serial port.

> The MPC866 has no RTC at all. Does it make a difference to busybox?


Steve Ballmer: Innovation!  Inigo Montoya: You keep using that word.
I do not think it means what you think it means.

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