Update README.threads to mention -DL.

p4raw-id: //depot/perl@60

diff --git a/README.threads b/README.threads
index 9e7b4d4..12abbe5 100644 (file)
--- a/README.threads
+++ b/README.threads
@@ -105,6 +105,18 @@ haven't tracked down yet) and there are very probably others too.
 * Plenty of others
 
 
+Debugging
+
+Use the -DL command-line option to turn on debugging of the
+multi-threading code. Under Linux, that also turns on a quick
+hack I did to grab a bit of extra information from segfaults.
+If you have a fancier gdb/threads setup than I do then you'll
+have to delete the lines in perl.c which say
+    #if defined(DEBUGGING) && defined(USE_THREADS) && defined(__linux__)
+        DEBUG_L(signal(SIGSEGV, (void(*)(int))catch_sigsegv););
+    #endif
+
+
 Background
 
 Some old globals (e.g. stack_sp, op) and some old per-interpreter