Getting a kernel crash dump

Matt Dillon posted this little note on how to get a kernel crash dump, which seems a good idea to archive – this may be useful again:

The best way is to get a kernel crash dump. If your swap area (typically ad0s1b) is large enough to accomodoate main memory, then ‘dumpon /dev/ad0s1b’ (and put ‘dumpdev=/dev/ad0s1b’ in your /etc/rc.conf), and then when it crashed and drops into DDB> type ‘panic’ and hit return twice and it should hopefully generate a crash dump.

For the crash dump to be really useful having the kernel.debug for the kernel that you are running is important. kernel.debug is built automatically when you buildkernel, but only the stripped ‘kernel’ version is actually installed. kernel.debug should still be sitting in the kernel build object directory which is usually /usr/obj/usr/src/sys/<KERNELNAME> (if you used ‘buildkernel’ to build your kernel).

doc framework arrives

Hiten Pandya has created a doc framework similar to the FreeBSD docs, though not yet as deep. If you are itching to contribute, and don’t want to code, this is an excellent alternative.

Chris Cleans up

Chris Pressey, the newest committer, has been in a cleanup frenzy – he’s had 140 commits already, many of them cleanup of the existing source code. Go Chris!

Build broken

Matt Dillon’s still missing some parts to the PIPE code in last night’s import from FreeBSD 5. Until this is fixed (hopefully by tomorrow) , the codebase will be somewhat unstable.

Now on BSDNews

If you have a login to BSDNews (and you should – it’s free), you can customize your BSDNews page layout to include the news feed from this very site, listed as “DragonFly BSD”! Thanks to Wes Peters and Chris Coleman for setting that up.

In Europe with 16EUR to spare?

Tobias Florek has plush Freds – the dragonfly mascot for DragonFly. He’s in Europe, and it costs 16 Euros plus shipping – mail fred at First come, first serve. If you live on the western side of the Atlantic, shipping costs make it prohibitive, so no luck for U.S. and Canada residents yet. (A U.S. distributor is being worked on.)


Andre Nathan submitted (and Matt Dillon committed) a change for route from NetBSD/OpenBSD that a ‘route show‘ command, which performs nearly the same as netstat -rn. Matt Dillon also added a -w option so that all columns would print full size.

More partition thoughts

Joerg Sonnenberger added to the partion discussion:

The alternative for /tmp is to have lots of swap and MFS for /tmp. This is often faster and avoids the lots of old crap in /tmp problem.
In that case you should make /var/tmp its own partition. In general /tmp and /var/tmp as world writable locations should be on partitions
on there own. Making /usr/obj a filesystem of its own has the advantage
of faster cleaning — just unmount, newfs and remount it :)

He also noted that having specific partitions for things like news spools (/news/) and mail stores (/var/spool/) is that it allows the blocksize to be set much smaller, which decreases wasted space when dealing with lots and lots of small files.

Partition sizing

Matt Dillon responded to a question from David Cuthbert about partition letters; as part of that, he recommended this sort of partion layout:

If you have a large system, it is often a good idea to separate out oft-written directories such as /usr/obj, and to make /tmp larger. /var/tmp is usually made a softlink to /tmp. If you have or intend to process a lot of mail, making /var larger is a good idea. If you are running a mail server it is often a good idea to make /var/spool its own partition (and /var/mail its own partition if you are running a large mail pop service or have a lot of users). If you are running a large web server making /usr/local/www its own partition (the base of Apache’s site directory) is a good idea.

Buildworld done; quickworld possible

Matt Dillon’s changes to buildworld are done; the next make buildworld you do will take a bit longer, but you should be able to do make quickworld thereafter, which should be… quicker!

Be careful, for the time being, doing a make -j, though. If that fails, Matt asks:

In one xterm: make -j 4 buildworld >& /tmp/bw.out
In another xterm: tail -f /tmp/bw.out | fgrep ===

Save the results, and post a link to it in the kernel discussion group.