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-rw-r--r--Documentation/ftrace.txt13
1 files changed, 12 insertions, 1 deletions
diff --git a/Documentation/ftrace.txt b/Documentation/ftrace.txt
index 79a80f7..35a78bc 100644
--- a/Documentation/ftrace.txt
+++ b/Documentation/ftrace.txt
@@ -324,7 +324,7 @@ output. To see what is available, simply cat the file:
cat /debug/tracing/trace_options
print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \
- noblock nostacktrace nosched-tree nouserstacktrace
+ noblock nostacktrace nosched-tree nouserstacktrace nosym-userobj
To disable one of the options, echo in the option prepended with "no".
@@ -381,6 +381,17 @@ Here are the available options:
userstacktrace - This option changes the trace.
It records a stacktrace of the current userspace thread.
+ sym-userobj - when user stacktrace are enabled, look up which object the
+ address belongs to, and print a relative address
+ This is especially useful when ASLR is on, otherwise you don't
+ get a chance to resolve the address to object/file/line after the app is no
+ longer running
+
+ The lookup is performed when you read trace,trace_pipe,latency_trace. Example:
+
+ a.out-1623 [000] 40874.465068: /root/a.out[+0x480] <-/root/a.out[+0
+x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
+
sched-tree - TBD (any users??)
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