Write a kernel dump
Syntax:
kdumper [-A|-a|-I] [-B] [-C|-c] [-K|-k] [-l size] [-U] [-v] [-w writer_name]
Options:
- -A | -a | -I
- -A: dump the memory allocated to user processes in addition
to the memory allocated for procnto and the code and
static data for the bootstrap executables in the image file system
(IFS).
- -a: dump the memory allocated to the active user process on
the CPU that caused the dump, in addition to the memory allocated for
procnto and the code and static data for the
bootstrap executables in the image file system (IFS).
- -I: dump all the IFS contents.
- Default behavior (none of -A, -a, nor
-I is specified) is to dump the memory allocated for
procnto and the code and static data for the
bootstrap executables in the image file system (IFS).
- -B
- By default, unless there's a physical address in the dump greater than 4 GB
kdumper writes the dump in the 32-bit ELF format. If
the dump contains a physical address greater than 4 GB, then
kdumper writes the dump in the 64-bit ELF format.
Specify the -B option to have kdumper
write the dump in the 64-bit ELF format in all cases.
- -C | -c
- -C: compress the dump file.
- -c: disable compression (default); reduces the amount of
memory used, but prevents compression being turned on later.
- -K | -k
- -K: attempt to invoke the kernel debugger when a dump is
requested. If the kernel debugger fails to clear the error condition,
dump.
- -k: don't check with the kernel debugger before dumping
(default).
- -l
size
- Set the size, in bytes, of the ring buffer used to record
kprintf() (kprintf() is a kernel
utility that produces (snprintf()-like output). Default is 512;
minimum is 100.
- -U
- Cause a kernel dump if an unhandled exception occurs on a user process, in
addition to the default behavior: cause a kernel dump if an unhandled
exception occurs while the kernel or a process manager is executing.
- -v[v..]
- Operate verbosely. Specify additional -v options to
increase verbosity. Default is quiet operation.
- -w
writer_name
- Specify the device to which kdump will write the dump.
Default is uuencode (see “Writers” below).
Description:
The kdumper utility writes out a memory dump which by default
includes the memory allocated for procnto and the code and static
data for the bootstrap executables in the image file system. You change this setting
so that the dump also includes the memory allocated to the active user process on
the CPU that caused the dump, the memory allocated to all user processes, or the
memory allocated to the entire IFS.
The dump is an ELF file (either 32-bit or 64-bit format; see “Options” above). GDB can't read this file
directly: use the kdserver
utility with GDB to parse and examine the dump file.
For more information about using GDB in a QNX Neutrino environment, see the entry for
gdb.
For more information about
GDB, see https://www.gnu.org/software/gdb/documentation/.
Including kdumper in your build
The kdumper utility is a bootstrap executable, so you need to
place it in the [virtual=] section of the inline bootstrap file of
your buildfile. Place it before procnto; if you are also loading
kdebug, place kdumper after
kdebug.
Writers
By default, kdumper dump is uuencoded. After uudecoding, the dump
file will be named kdump.elf (default, or -c
option) if uncompressed, or kdump.elf.gz if compressed
(-C option), which you can uncompress with the gunzip utility.
The following other writers are available with kdumper:
- dummy
- Discard the dump; used for debugging kdumper.
- external
- Use the writer specified after kdumper in the buildfile's
inline bootfile.