trace: add syslog tracing backend
This patch adds a tracing backend which sends output using syslog().
The syslog backend is limited to POSIX compliant systems.
openlog() is called with facility set to LOG_DAEMON, with the LOG_PID
option. Trace events are logged at level LOG_INFO.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Message-id: 1470318254-29989-1-git-send-email-paul.durrant@citrix.com
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/docs/tracing.txt b/docs/tracing.txt
index 29f2f9a..e62444c 100644
--- a/docs/tracing.txt
+++ b/docs/tracing.txt
@@ -192,6 +192,18 @@
Restriction: "ftrace" backend is restricted to Linux only.
+=== Syslog ===
+
+The "syslog" backend sends trace events using the POSIX syslog API. The log
+is opened specifying the LOG_DAEMON facility and LOG_PID option (so events
+are tagged with the pid of the particular QEMU process that generated
+them). All events are logged at LOG_INFO level.
+
+NOTE: syslog may squash duplicate consecutive trace events and apply rate
+ limiting.
+
+Restriction: "syslog" backend is restricted to POSIX compliant OS.
+
==== Monitor commands ====
* trace-file on|off|flush|set <path>
