On 2008-11-24, at 1:51 , Barbara wrote:
About kgdb...
I never used freebsd-update, so sorry if I'm saying
something
stupid, but could it be the case that the kernel has been
built
without debugging symbols or something like that? Does freebsd-
update provide a kernel.debug?
I haven't had to use a the kernel.
debug file
in the obj dir in a long
time. As far as I know, these days,
the GENERIC
kernel includes debug
symbols. And in cases when there
aren't any debug
symbols, that
shouldn't prevent kgdb from loading, I
wouldn't think.
Hello,
I had a k panic some hours ago but I think
that's related to a
problem with one
of my HDs.
I've got a dump
in /var/crash, and as you were interested, I run:
# kgdb
/boot/kernel/kernel /var/crash/vmcore.6
GNU gdb 6.1.1
[FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free
software, covered by the GNU General Public License, and you are
welcome
to change it and/or 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.
This GDB was configured as i386-
marcel-freebsd...(no debugging
symbols found)...
Attempt to extract a
component of a value that is
not a structure pointer.
Attempt to extract a
component of a value
that is not a structure pointer.
Attempt to extract a
component of
a value that is not a structure pointer.
Attempt to extract a
component of a value that is not a structure pointer.
Terminated
I had
to pkill kgdb as it was in a loop.
Running it against kernel.
debug in
/usr/obj/usr/src/sys/$KERNCONF/ worked as expected.
I've always
followed this
way, so I don't know if it was working with earlier releases.
Ah, well you must not be using GENERIC then, because it does have the
debugging symbols.
I think this is the setting in the GENERIC config that
controls it:
makeoptions DEBUG=-g
But I guess what you're doing works if
you're using a custom kernel
that does not have that config setting.
-
rory
I'm not using GENERIC but I have
makeoptions DEBUG=-g
in my KERNCONF.
Barbara,
Ah, so you had the exact same results I got, when using /book/kernel/
kernel. So, that answers that question then, apparently I do need to
build a kernel.debug to get a backtrace on 6.4.
So, it looks like maybe things are different in 6 than I had
remembered. I haven't looked at the 6.4-RC2 notebook to see what the
kernel directory has, but on my 7.0 server at least, I've noticed that
kgdb(1) does work with /book/kernel/kernel, and I think it might have
to do with putting the symbols in a separate, kernel.symbols file. So,
I assume that this doesn't exist on 6. However I did notice that if I
remove that file, and run kgdb again (on 7.0) I also get that
structure pointer error that you get, it doesn't lock up.. and I can
still get a backtrace, but the output is more terse.. in that it shows
function names, but without corresponding source file names and line
numbers. So, the addition of the symbols file it seems, adds some some
more debugging information than what the kernel provides by itself.
So, maybe that makeoptions directive does different things on each
version.
Thank you for your feedback with this, much appreciated. Now, to see
if I can build a kernel.debug on that machine, can get a backtrace --
though it sure sounds like a problem with ata(4).
- rory
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