dump
Write a dump file for the guest
Synopsis:
dump directory
dump |shell_commandOptions:
- directory
- The output directory in the host.
or:
- |shell_command
- If the first character of the argument is a pipe, the characters that follow it are spawned as a shell command in the host, and the contents of the dump file are written to the shell's standard input.
Description:
On receipt of a SIGUSR2 signal or when triggered by a watchdog (see
Watchdogs
in the
QNX Hypervisor: Protection Features
chapter), write a dump file
for a guest hosted in this
qvm process instance. If the argument does not start
with a pipe (
), write the dump file to the directory
specified by directory. If the argument starts with pipe, spawn a
shell command instead.|
The dump file
The dump file is called prefix-YYYYMMDD-hhmmsss.gcore where:
- prefix is the name of the VM hosting the guest, as specified by the system option; if the system option isn't specified (see system in this chapter), prefix is set to qvm-guest
- YYYYMMDD-hhmmss is the host date and time at the moment that the dump is requested
If a file with the name that the qvm process composes for the dump file already exists in the specified directory, the qvm process attempts to generate a unique name by inserting a hyphen and a number from 1 to 9 (-1, -2, ... -9) before the .gcore extension. For example, if the files qnx8-20170821-120619 and qnx8-20170821-120619-1 exist, the qvm process creates a file called qnx8-20170821-120619-2. If the qvm process is unable to create a unique filename, it doesn't create a dump file.
The dump file is output in ELF64 format. A PT_NOTE segment has the
register states for the vCPUs, and PT_LOAD segments have the guest
memory contents. The format of the PT_NOTE segment is described by
the sys/kdump.h public header file.
To interpret the dump file, you can use GDB and kdserver (see
kdserver
in the
QNX OS Utilities Reference).
Example:
dump "|gzip >dump_output.gz"