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From: Mattias.Gronlund@sa.erisoft.se (Mattias Gronlund)
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Subject: Problems using kerneldump
To: FreeBSD-current@FreeBSD.ORG
Date: Mon, 26 Feb 1996 21:14:49 +0100 (MET)
Cc: Mattias.Gronlund@sa.erisoft.se
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Hi,

I have some problems with the nfs code when running netbooted and 
current from 960226, the problem is that I get log messages saying
biodone: buffer already done
when running kvm_mkdb and when saving files with vi. At last I
managed to get the symboltable accessible for ddb and could
insert a panic line in the biodone routine so that I could get
a trace and se that the faulty call come from the nfs-code.

I then decided that I should try get a core to debug with gdb -k to
get that I used `call dumpsys' in ddb and the system dumped the core.
I then rebooted and run `savecore /mnt' waited for a while.
Then when trying to debug the core all I got was this:

bash# gdb -k kernel /mnt/vmcore.0 
GDB is free software and you are welcome to distribute copies of it
 under certain conditions; type "show copying" to see the conditions.
There is absolutely no warranty for GDB; type "show warranty" for details.
GDB 4.13 (i386-unknown-freebsd), 
Copyright 1994 Free Software Foundation, Inc...
IdlePTD 909000
current pcb at 1efd3c
panic: biodone: buffer already done
 
#0  0x0 in ?? ()
(kgdb) where
#0  0x0 in ?? ()
(kgdb) 

I had expected to get a backtrace like the one in ddb and some way to 
see what was going on.

Can this have someting with the fact that I did go multiuser before
running savecore, can it have something to do with the fact that
I'm netbooting the machine or what can it be I'm doing wrong?

/Mattias