Question about docs and FreeBSD CURRENT

Phil Eaton philneaton95 at gmail.com
Thu Jan 25 14:37:48 UTC 2018


Hey! I was recently trying to debug a kernel module that causes a kernel
panic on load. I tried following the docs in the FreeBSD Handbook for
debugging a kernel panic, but a few of the steps were slightly off for me
on CURRENTl. The docs do clearly state that the docs are only for
10.4-RELEASE and 11.1-RELEASE. So my first question: is there a hosted
version (e.g. freebsd.org/doc/CURRENT/en/books) of the handbook that tracks
CURRENT? If not, do I just have to follow along on CURRENT of the docs svn
repo and build the docs myself manually to see current information?

In particular I was confused about all the references to kgdb in the
FreeBSD handbook docs related to debugging the kernel. On my system there
was no kgdb and there is no gdb of course by default either because FreeBSD
switched off it. I later understood that I could just install gdb from
ports and run `gdb -k` to get similar behavior. But the docs continued to
suggest that kgdb was a built-in binary. Later I found out that kgdb _is_
in fact installed on the base system but it was in an undocumented
location: /usr/libexec/kgdb.

The next issue I had was which directory to start in to find debugging
symbols. The docs suggested going to */usr/obj/usr/src/sys/**KERNCONF* but
I actually had to go to */usr/obj/usr/src/amd64.amd64/sys/GENERIC*. I don't
know if this is because I installed the system oddly (I don't believe I
did), or if this was a location change in CURRENT.

In any case, I'm just trying to find the best way to stay current on docs
while I'm running CURRENT. If any of these notes I made has not yet been
updated in docs, I'd be happy to submit some changes myself.

Thank you!

-- 
Phil Eaton


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