[Crash-utility] snap crash plugin on RHEL 4

[Dave Anderson]

----- "Adrien Kunysz" <adk at redhat.com> wrote:

> Dear crash-utility list,
> 
> I played a bit with snap on RHEL 4 and besides the fact it doesn't build out of 
> the box (trivial Makefile compatibility problem), it seems it doesn't really 
> dump a full core properly (at least on the system I tested).
> 
> Since this is not really something that is supposed to be supported I am posting 
> this here rather than opening a Bugzilla. I haven't attempted to repro on other 
> distros.
> 
> # crash
> crash> extend snap-rhel4-x86_64/snap.so
> ./snap-rhel4-x86_64/snap.so: shared object loaded
> crash> snap mycore
> mycore: [100%]
> -rw-r--r--  1 root root 4160684848 Sep  3 09:37 mycore
> crash> quit
> # free
>               total       used       free     shared    buffers    
> cached
> Mem:      16319168    8065516    8253652          0     133060   
> 6231128
> -/+ buffers/cache:    1701328   14617840
> Swap:      2097144          0    2097144
> # uname -a
> Linux *** 2.6.9-89.ELsmp #1 SMP Mon Apr 20 10:33:05 EDT 2009 x86_64
> x86_64 
> x86_64 GNU/Linux
> # crash /usr/lib/debug/lib/modules/2.6.9-89.ELsmp/vmlinux mycore
> [...]
> crash: read error: kernel virtual address: 1020009d024  type:
> "tss_struct ist array"
> 
> Is that expected? Any idea what's going on?

It created at 4GB vmcore on a 16GB system, which is apparently the
problem.  Try doing this (done on my 1GB RHEL4 box):

  crash> !tty
  /dev/pts/3
  crash> set console /dev/pts/3
  debug console [11505]: /dev/pts/3
  console: /dev/pts/3
  crash> extend snap.so
  ./extensions/snap.so: shared object loaded
  crash> snap mycore
  00000000-0009ffff : System RAM
  00100000-3fe8abff : System RAM
  ram_segments[0]: 0000000000000000 00000000000a0000 [00000000-0009ffff]
  ram_segments[1]: 0000000000100000 000000003fe8a000 [00100000-3fe8abff]
  mycore: [100%] 
  -rw-r--r--  1 root root 1072210680 Sep  3 09:24 mycore
  crash> 

I'm guessing that the memory containing virtual address 0x1020009d024
(physical 0x20009d024) is not there for some reason.

Dave