View source for Core dump

==Article purpose==
This article provides the initial information set needed to start the '''core dump''' Linux<sup>&reg;</sup> service.

== Introduction ==
{{:Trace_and_debug_tools_assignment_table_template}}
<onlyinclude>
| [[Core dump|systemd core dump]]
| [[:Category:Debugging tools|Debugging tools]]
| style="text-align:left;" | '''systemd core dump''': generates core dump files on Linux<br>
| {{Y}} || {{N}} || {{Y}} || {{N}} || {{N}} || {{N}}
|-
</onlyinclude>
|}

'''core dump''' records the states of the working program memory before an abnormal termination. The dump record assists in diagnosing and debugging program errors.

'''Systemd''' provides, via a configuration file, a way to generate and store core dump for Linux system.

== Installing the trace and debug tool on your target board==
=== Using STM32MPU Embedded Software Distribution ===
==== Distribution Package ====
ST via OpenSTLinux layer provides a recipe named '''systemd-conf''', which provides a core dump configuration for systemd.

The '''core dump''' configuration is available only via OpenSTLinux distribution. If this configuration is activated via another distribution, an add-on must be made in the systemd-conf recipe. 

recipes-core/systemd/systemd-conf.bbappend:
<pre>
do_install_append() {
    install -d ${D}${sysconfdir}/systemd/coredump.conf.d/
    echo "[Coredump]" > ${D}${sysconfdir}/systemd/coredump.conf.d/coredump-custom.conf
    echo "Storage=external" >> ${D}${sysconfdir}/systemd/coredump.conf.d/coredump-custom.conf
}
</pre>

== Getting started ==
=== Verify setup ===

* Verify configuration are present
 {{Board$}} ls /etc/systemd/coredump.conf.d/
 coredump-custom.conf

* Verify if '''core dump''' is registered by Linux
 {{Board$}} cat /proc/sys/kernel/core_pattern
 |/lib/systemd/systemd-coredump %P %u %g %s %t %c %h %e

=== Crash append===
If an application/program has crashed and generated a core dump while running, the core dump result is stored in '''''/var/lib/systemd/coredump'''''.

(See the [[Core_dump#How to test core dump|How to test core dump]] service below ).

==How to test core dump==
* Launch a program
Launch a program (for example: "weston-flower")
 {{Board$}} weston-flower &

* Get the pid of this program with the ps command
 {{Board$}} ps ax | grep <program>

* kill the program with specific '''ILL''' (4) signal (ILL: Illegal instruction)
 {{Board$}} kill -4 <pid of program>
Force to generate core dump (for example)
 {{Board$}} kill -4 `pidof weston-flower`

* check ''/var/lib/systemd/coredump/'', the core dump associated to this abnormal termination:
 {{Board$}} find /var/lib/systemd/coredump/
/var/lib/systemd/coredump/
/var/lib/systemd/coredump/core.weston-flower.0.47f9def8d0f44af5919d0e4cd5ee04ae.554.1543488316000000.xz


The core dump generated has a size of around 300 Kbytes
 {{Board$}} du -sh /var/lib/systemd/coredump/*
 295K /var/lib/systemd/coredump/core.weston-flower.0.47f9def8d0f44af5919d0e4cd5ee04ae.554.1543488316000000.xz

== To go further ==
To make core analysis please refer to [[GDB#Core_dump_analysis_using_GDB]]

==Documentation and web articles==
<references />

{|
|+ "External links"
|-
! scope=col | Document link
! scope=col | Document Type
! scope=col | Description
|-
| [https://www.freedesktop.org/software/systemd/man/coredump.conf.html systemd man page for core dump configuration]
| Standard
| systemd man page
|}

{{ ArticleBasedOnModel | Trace and debug tools article model}}
{{ PublicationRequestId | 10302 | 16Jan'19 }}

[[Category:Linux debugging tools]]