Add configuration options.

Makefile.rule

@@ -159,6 +159,19 @@ COMMON_PROF = -pg
 # Build Debug version
 # DEBUG = 1
 
+# Improve GEMV and GER for small matrices by stack allocation.
+# For details, https://github.com/xianyi/OpenBLAS/pull/482
+#
+# MAX_STACK_ALLOC=2048
+
+# Add a prefix or suffix to all exported symbol names in the shared library.
+# Avoid conflicts with other BLAS libraries, especially when using
+# 64 bit integer interfaces in OpenBLAS.
+# For details, https://github.com/xianyi/OpenBLAS/pull/459
+#
+# SYMBOLPREFIX=
+# SYMBOLSUFFIX=
+
 #
 #  End of user configuration
 #