X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/0a34949459c8ec5f79599a458704b7b11cdbb248..a466d09b249d5018ecb0f1ec45adba545c02c75b:/src/OS/Makefile-Linux

diff --git a/src/OS/Makefile-Linux b/src/OS/Makefile-Linux
index 4fe2436a6..990f884e9 100644
--- a/src/OS/Makefile-Linux
+++ b/src/OS/Makefile-Linux
@@ -1,7 +1,9 @@
-# $Cambridge: exim/src/OS/Makefile-Linux,v 1.4 2008/08/11 15:30:02 fanf2 Exp $
-
 # Exim: OS-specific make file for Linux. This is for modern Linuxes,
 # which use libc6.
+#
+# For Linux, we assume GNU Make; at time of writing, the only extension
+# used is ?= which is actually portable to other maintained Make variants,
+# just is not POSIX.
 
 HAVE_ICONV=yes
 
@@ -10,8 +12,9 @@ CHOWN_COMMAND=look_for_it
 CHGRP_COMMAND=look_for_it
 CHMOD_COMMAND=look_for_it
 
-CFLAGS=-O -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
-CFLAGS_DYNAMIC=-shared -rdynamic
+# Preserve CFLAGS and CFLAGS_DYNAMIC from the caller/environment
+CFLAGS ?= -O -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
+CFLAGS_DYNAMIC ?= -shared -rdynamic
 
 DBMLIB = -ldb
 USE_DB = yes