PR6930: stap: supports on-file flight recorder options

Add on-file flight recorder options (the combination of -F and -o,
and -S option) to stap command, and change manpages and NEWS.
 - Both of -F and -o is specified, stap passes -D option to staprun.
 - stap just passes -S option to staprun.

1 files changed, 17 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index fff8afc9..d85ec2c0 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,22 @@
 * What's new
 
+- On-file flight recorder is supported. It allows stap to record huge
+  trace log on the disk and to run in background.
+  Passing -F option with -o option runs stap in background mode. In this
+  mode, staprun is detached from console, and stap itself shows staprun's
+  pid and exits.
+  Specifying the max size and the max number of log files are also available
+  by passing -S option. This option has one or two arguments seperated by
+  a comma. The first argument is the max size of a log file in MB. If the
+  size of a log file exceeds it, stap switches to the next log file
+  automatically. The second is how many files are kept on the disk. If the
+  number of log files exceeds it, the oldest log file is removed
+  automatically. The second argument can be omitted.
+
+  For example, this will record output on log files each of them is smaller
+  than 1024MB and keep last 3 logs, in background.
+    % stap -F -o /tmp/staplog -S 1024,3 script.stp
+
 - In guru mode (-g), the kernel probing blacklist is disabled, leaving 
   only a subset - the kernel's own internal kprobe blacklist - to attempt
   to filter out areas unsafe to probe.  The differences may be enough to