News Group Posts

create panic crash on osr5

From: Bela Lubkin <belal@sco.com>
Subject: Re: How To Create a Panic?
Date: Mon, 11 Feb 2002 09:18:33 GMT
References: <3c66f55a.26365010@news.texas.net> 

Carl Sawyer

> We have panic woes and too much memory to save a dump in swap.  Later
> today we will mount a new disk and leave a raw partition which will
> become the default dump device.  I am putting together a procedure for
> on-site operators to save the image when the system panics.  I want to
> test my procedure on another very similar system.  How can I induce a
> panic that will write to this default dump area?  Any other ideas or
> suggestions?
> 
> Details:
> SCO OSR 5.0.4
> 2 gig RAM

Add the following to the end of /etc/conf/node.d/mm:

=============================================================================
# The following devices are not normally enabled.
#
# /dev/io[bwl] provide byte, word and longword access to I/O space.  The
# semantics may be somewhat unexpected, as the kernel automatically
# seeks forward after I/O.  For best results, always lseek() the desired
# address before reading/writing.  Access must be restricted as these
# devices can be used to crash the system, take it over, or worse.
#
# /dev/panic causes a deliberate kernel panic when read from or written
# to.
#
# mm    iob     c       3       root    sys     600
# mm    iow     c       4       root    sys     600
# mm    iol     c       5       root    sys     600
# mm    panic   c       6       root    sys     600
=============================================================================

If you uncomment (remove the "# " from) the lines that start with
"# mm", then relink the kernel, /dev/panic will be created.  Reading or
writing that device panics the system.  (Only root can open it.)

The other devices provide access to I/O device space, might be useful
for programmers.  /dev/io[bwl] apply to releases back to SCO Unix 3.2.0,
probably also SCO Xenix.  /dev/panic applies to OpenServer 5.0.4 and
later.

Meanwhile, you might find this useful.  You can deliberately boot your
system with less RAM than is physically present.  Run `divvy /dev/swap`
and see how big swap is.  Convert to megabytes.  Then reboot and, at the
boot prompt, enter:

  Boot
  : defbootstr mem=1m-256m

Replace "256" with the actual size of swap, in megabytes.  You might
want to err a bit on the small side to avoid arithmetic errors due to
the mass confusion about what a megabyte is.

Once booted this way, a panic should successfully write a dump to swap.
Of course this is only helpful if your swap is big enough for the system
to work with that little RAM...

>Bela<
 

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