coccicheck: add support for DEBUG_FILE

[linux-2.6-block.git] / Documentation / coccinelle.txt

diff --git a/Documentation/coccinelle.txt b/Documentation/coccinelle.txt
index 64daaf18874b4557ab71765f1e3d8f698c642c15..2516c5ef16916451d9292243fbcde090470d1bbb 100644 (file)
--- a/Documentation/coccinelle.txt
+++ b/Documentation/coccinelle.txt
@@ -157,6 +157,26 @@ semantic patch as shown in the previous section.
 The "report" mode is the default. You can select another one with the
 MODE variable explained above.
 
+ Debugging Coccinelle SmPL patches
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Using coccicheck is best as it provides in the spatch command line
+include options matching the options used when we compile the kernel.
+You can learn what these options are by using V=1, you could then
+manually run Coccinelle with debug options added.
+
+Alternatively you can debug running Coccinelle against SmPL patches
+by asking for stderr to be redirected to stderr, by default stderr
+is redirected to /dev/null, if you'd like to capture stderr you
+can specify the DEBUG_FILE="file.txt" option to coccicheck. For
+instance:
+
+    rm -f cocci.err
+    make coccicheck COCCI=scripts/coccinelle/free/kfree.cocci MODE=report DEBUG_FILE=cocci.err
+    cat cocci.err
+
+DEBUG_FILE support is only supported when using coccinelle >= 1.2.
+
  Additional flags
 ~~~~~~~~~~~~~~~~~~