dpif-netdev: Make datapath and flow stats atomic.

[cascardo/ovs.git] / INSTALL.md

diff --git a/INSTALL.md b/INSTALL.md
index b2b0cbb..8156898 100644 (file)
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -196,6 +196,20 @@ To use 'clang' compiler:
 
       `% ./configure CC=clang`
 
+To supply special flags to the C compiler, specify them as CFLAGS on
+the configure command line.  If you want the default CFLAGS, which
+include "-g" to build debug symbols and "-O2" to enable optimizations,
+you must include them yourself.  For example, to build with the
+default CFLAGS plus "-mssse3", you might run configure as follows:
+
+      `% ./configure CFLAGS="-g -O2 -mssse3"`
+
+Note that these CFLAGS are not applied when building the Linux
+kernel module.  Custom CFLAGS for the kernel module are supplied
+using the EXTRA_CFLAGS variable when running make.  So, for example:
+
+      `% make EXTRA_CFLAGS="-Wno-error=date-time"
+
 To build the Linux kernel module, so that you can run the
 kernel-based switch, pass the location of the kernel build
 directory on --with-linux.  For example, to build for a running
@@ -259,6 +273,10 @@ Building the Sources
    For improved warnings if you installed "sparse" (see "Prerequisites"),
    add C=1 to the command line.
 
+   Some versions of Clang and ccache are not completely compatible.
+   If you see unusual warnings when you use both together, consider
+   disabling ccache for use with Clang.
+
 2. Consider running the testsuite.  Refer to "Running the Testsuite"
    below, for instructions.