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authorStefan Hajnoczi <stefanha@linux.vnet.ibm.com>2011-09-05 16:31:45 +0100
committerStefan Hajnoczi <stefanha@linux.vnet.ibm.com>2011-09-21 11:29:45 +0100
commit8f6421179ad29cbdaa9d5c5b39e9c001996c0f07 (patch)
treea79d31efd1b4ea8c11cac152754786dc5c9c5edf /docs
parent27cdad67a1bc23b38c765b677ed8064bfb8d3e44 (diff)
trace: allow trace events with string arguments
String arguments are useful for producing human-readable traces without post-processing (e.g. stderr backend). Although the simple backend cannot handles strings all others can. Strings should be allowed and the simple backend can be extended to support them. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Diffstat (limited to 'docs')
-rw-r--r--docs/tracing.txt8
1 files changed, 3 insertions, 5 deletions
diff --git a/docs/tracing.txt b/docs/tracing.txt
index d0171aabda..2c33a62b98 100644
--- a/docs/tracing.txt
+++ b/docs/tracing.txt
@@ -70,11 +70,6 @@ Trace events should use types as follows:
cannot include all user-defined struct declarations and it is therefore
necessary to use void * for pointers to structs.
- Pointers (including char *) cannot be dereferenced easily (or at all) in
- some trace backends. If pointers are used, ensure they are meaningful by
- themselves and do not assume the data they point to will be traced. Do
- not pass in string arguments.
-
* For everything else, use primitive scalar types (char, int, long) with the
appropriate signedness.
@@ -182,6 +177,9 @@ source tree. It may not be as powerful as platform-specific or third-party
trace backends but it is portable. This is the recommended trace backend
unless you have specific needs for more advanced backends.
+The "simple" backend currently does not capture string arguments, it simply
+records the char* pointer value instead of the string that is pointed to.
+
==== Monitor commands ====
* info trace