diff --git a/lisp/Config.sun4_solaris_gcc b/lisp/Config.sun4_solaris_gcc
index 368851c7b29efad9b01fc27a77d6c7b3e2d038ba..1744964f1a4955728347be9336467aad46cd031c 100644
--- a/lisp/Config.sun4_solaris_gcc
+++ b/lisp/Config.sun4_solaris_gcc
@@ -40,6 +40,15 @@ endif
 
 CPPFLAGS = -I. -I$(PATH1) -I/usr/openwin/include -I/usr/include/X11 -DSOLARIS -DSOLARIS25 -DSVR4 $(CC_V8PLUS) $(LINKAGE) $(GENCGC)
 
+# Note: If you want to be able to run gdb with cmucl, the only version
+# of gdb that still works for me (rtoy) on Solaris is 4.18.  Versions
+# 5.x and later (including 6.3) are incapable of passing signals
+# (SIGILL and SIGSEGV) to lisp properly.
+#
+# But, gcc 3.3.3 and later appear to produce executables that gdb 4.18
+# can't handle.  So, we should probably stick with gcc 3.3.2.  Adjust
+# the CC variable appropriately, if necessary.
+
 CC = gcc -O -Wall
 CPP = gcc -E
 CFLAGS = -g $(AS_V8PLUS)