NAME

bsdcrashtar —

archive kernel crash files

SYNOPSIS

bsdcrashtar [options] [<crash.tar.gz>]

DESCRIPTION

The bsdcrashtar utility creates tar a archive that contains all files needed for debugging FreeBSD kernel crash (vmcore, kernel, loaded modules, sources that appear in backtrace). This is useful for debugging a crash on another host, sending it to developers or if you are going to upgrade the kernel on crashed host but would like to keep crashdump in case the developers ask you to provide additional info.

Created tar archive contains also a script that when being run inside unpacked archive will give kgdb(1) session with crash core loaded in it. The script should be run with root privileges because it does chroot(8) before starting kgdb(1).

By default, bsdcrashtar archives the most recent core dump in the core dump directory. A specific core dump may be specified via either the core or dumpnr arguments. Once bsdcrashtar has located a core dump, it analyzes the core dump to determine the exact version of the kernel that generated the core. It then looks for a matching kernel file under each of the subdirectories in /boot. The location of the kernel file can also be explicitly provided via the kernel argument. By default the resulting tar archived is stored in the core dump directory with a name crash.XX.tar.gz.

The options are as follows:

-h: Print the minihelp and exit.
-d crashdir: Specify an alternate core dump directory. The default crash dump directory is /var/crash.
-n dumpnr: Use the core dump saved in vmcore.dumpnr instead of the latest core in the core dump directory.
-k kernel: Specify an explicit kernel file.
-c core: Specify an explicit core file.

WARNING

As a core file presents a content of a kernel virtual memory at the moment of the crash it might contain information you would not like to become public. So think twice before giving the access to a core to other person.

LIMITATIONS

You can debug an archived crash only on a host of the same hardware platform running FreeBSD of the same major version (abi compatible).

AUTHOR

Mikolaj Golub.

BUGS

As it is rather experimental utility and depends on proper parsing of gdb(1) output it is highly recommended to check created tar archive if you want to be sure it contains all necessary files.