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Message-ID: <19980105114732.14617@lemis.com>
Date: Mon, 5 Jan 1998 11:47:32 +1030
From: Greg Lehey <grog@lemis.com>
To: Stanley.Hopcroft@aipo.gov.au
Cc: questions@FreeBSD.ORG
Subject: Re: lnc problems: very slow then panic 12 while login during FTP
References: <4A256583.000814DE.00@notes.aipo.gov.au>
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In-Reply-To: <4A256583.000814DE.00@notes.aipo.gov.au>; from Stanley.Hopcroft@aipo.gov.au on Mon, Jan 05, 1998 at 09:34:16AM +1000
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On Mon, Jan 05, 1998 at 09:34:16AM +1000, Stanley.Hopcroft@aipo.gov.au wrote:
>
> I am writing to say that the problem with my system, possibly related to
> 2.2.5 and the lnc driver, seems to be getting worse.
>
> While logging in to look at netstat -Iln1 1 during a very slow FTP (see
> previous letter commenting on slowness of lnc driver with 2.2.5) 

Sorry, I didn't see your previous message.

> the kernel panicked
>
> Fatal trap 12:      page fault while in kernel mode
> fault virt address: 0x f1 0b 67 ae
> fault code:         supervisor read, page not present
> ip:                 0x8: 0xf0 12 5a 7c
> sp:                 0x10:0xef bf fd 20
> fp:                 "
> cs:                 base 0x0 limit 0xfffff type 0x1b
>                     - DPE, pres1, def321, gran1
> processor eflags    = int enable, resume, IOPL = 0
> current process     = login (177)
> int mask            = bio
> panic page fault.
>
> Any help will be greatly appreciated.

This particular panic is about the most unspecific we have.
Translated into Microsoft, it means "General Protection Error".  About
the only clue we have is the IP value, which you could look up in an
nm of the kernel:

$ nm /kernel | sort | more

Page through the output until you find an address close to 0xf0125a7c.
On my kernel, I get the followoing in this area:

f0125840 t _semundo_adjust
f012592c t _semundo_clear
f01259a0 T ___semctl
f0125f04 T _semget
f012613c T _semop

Your results will be very different.

Of course, if this is likely to happen again, you should enable
dumping.  In /etc/rc.conf, ensure that you have something like:

savecore_enable="YES"   # Save kernel crashdumps for debugging (or NO).
dumpdev="/dev/sd0b"     # Device name to crashdump to (if enabled).

The name of the dumpdev should be the name of a swap partition at
least the size of physical memory.  Make sure also that you have a
directory /var/crash on a file system with enough free space to store
the dump (memory size) and the kernel (1.? MB).  If you then get the
panic again, I can give you some suggestions about what to look for.
Check also the online handbook, which contains some material about
this.

Greg