Интерактивная система просмотра системных руководств (man-ов)
textdump (4)
>> textdump (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
textdump
- textdump kernel dumping facility
SYNOPSIS
options KDBoptions DDB
DESCRIPTION
The
facility allows the capture of kernel debugging information to disk in a
human-readable rather than the machine-readable form normally used with
kernel memory dumps and minidumps.
This representation, while less complete in that it does not capture full
kernel state, can provide debugging information in a more compact, portable,
and persistent form than a traditional dump.
By combining
with other
ddb(4)
facilities, such as scripting and output capture, detailed bug information
can be captured in a fully automated manner.
FORMAT
data is stored in a dump partition in the same style as a regular memory
dump, and will be automatically extracted by
savecore(8)
if present on boot.
files are stored in the
tar(5)
format, and consist of one or more text files, each storing a particular type
of debugging output.
The following parts may be present:
ddb.txt
Captured
ddb(4)
output, if the capture facility has been used.
May be disabled by clearing the
debug.ddb.textdump.do_ddb
sysctl.
config.txt
Kernel configuration, if
Od options INCLUDE_CONFIG_FILE
has been compiled into the kernel.
May be disabled by clearing the
debug.ddb.textdump.do_config
sysctl.
msgbuf.txt
Kernel message buffer, including recent console output if the capture
facility has been used.
May be disabled by clearing the
debug.ddb.textdump.do_msgbuf
sysctl.
panic.txt
Kernel panic string, if the kernel panicked before the dump was generated.
May be disabled by clearing the
debug.ddb.textdump.do_panic
sysctl.
version.txt
Kernel version string.
My be disabled by clearing the
dbeug.ddb.textdump.do_panic
sysctl.
Kernel textdumps may be extracted using
bsdtar(1).
CONFIGURATION
The
facility is enabled as part of the kernel debugger using
options KDB
and
options DDB
By default, kernel dumps generated on panic or via explicit requests for a
dump will be regular memory dumps; however, by using the
textdump set
command in
ddb(4),
or by setting the
debug.ddb.textdump.pending
sysctl to 1 using
sysctl(8),
it is possible to request that the next dump be a textdump.
If at the
ddb(4)
command line, the commands
textdump settextdump status
and
textdump unset
may be used to set, query, and clear the textdump pending flag.
As with regular kernel dumps, a dump partition must be automatically or
manually configured using
dumpon(8).
EXAMPLES
In the following example, the script
kdb.enter.panic
will run when the kernel debugger is entered as a result of a panic, enable
output capture, dump several useful pieces of debugging information, and then
invoke panic in order to force a kernel dump to be written out followed by a
reboot:
script kdb.enter.panic=textdump set; capture on; show allpcpu; bt;
ps; alltrace; show alllock; call doadump; reset
In the following example, the script
kdb.enter.witness
will run when the kernel debugger is entered as a result of a witness
violation, printing lock-related information for the user:
