Compiling the current release of vde2-2.2.2 gives compilation errors due to a missing macro variable in the code. I’ve done a dirty hack to get it compiled but haven’t tested to know if the hack has any side effects. It seems like a simple enough hack so I decided I’d write a post about it anyway as I’ve been seeing quite a bit of queries about vde networking.

Getting the source/packages

It doesn’t seem like a lot of linux distributions provide vde as a package so the best way to get access to the code is to get it directly from the official soureforge.net link that can be found here at sourceforge. The current version 2.2.2, however, will not compile so I’ve included my hacked version at the bottom of this post which should successfully compile. The compilation error has already been submitted to the project’s bug tracking so hopefully it will be fixed by the maintainers soon. The patch for the hacked version is listed below and also included as a file at the end of this post.

diff --git a/src/kvde_switch/consmgmt.c b/src/kvde_switch/consmgmt.c
index bde7fea..491e3c4 100644
--- a/src/kvde_switch/consmgmt.c
+++ b/src/kvde_switch/consmgmt.c
@@ -32,6 +32,7 @@
 #include "../vde_switch/switch.h"
 #include "sockutils.h"
 #include "consmgmt.h"
+#include "../slirpvde/tcp2unix.h"
 
 #define MAXCMD 128
 
diff --git a/src/kvde_switch/datasock.c b/src/kvde_switch/datasock.c
index 53311c8..4758f4c 100644
--- a/src/kvde_switch/datasock.c
+++ b/src/kvde_switch/datasock.c
@@ -34,6 +34,7 @@
 #include "../vde_switch/switch.h"
 #include "sockutils.h"
 #include "consmgmt.h"
+#include "../slirpvde/tcp2unix.h"
 
 /* will be inserted in a af_ipn.h include */
 #ifndef AF_IPN
diff --git a/src/slirpvde/tcp2unix.h b/src/slirpvde/tcp2unix.h
index 62a6042..af1be54 100644
--- a/src/slirpvde/tcp2unix.h
+++ b/src/slirpvde/tcp2unix.h
@@ -9,6 +9,10 @@
 #define UNIX_PATH_MAX 108
 #endif
 
+#ifndef PATH_MAX
+#define PATH_MAX 108
+#endif
+
 extern int tcp2unix_check;
 
 void tcp2unix_add(int port,char *path);
diff --git a/src/vde_plug2tap.c b/src/vde_plug2tap.c
index 75e6aee..22d2e28 100644
--- a/src/vde_plug2tap.c
+++ b/src/vde_plug2tap.c
@@ -23,6 +23,7 @@
 #include <vde.h>
 #include <vdecommon.h>
 #include <libvdeplug.h>
+#include "slirpvde/tcp2unix.h"
 
 #define BUFSIZE 2048
 
diff --git a/src/wirefilter.c b/src/wirefilter.c
index 7a8159a..c996e0b 100644
--- a/src/wirefilter.c
+++ b/src/wirefilter.c
@@ -36,6 +36,7 @@
 #include <vde.h>
 #include <vdecommon.h>
 #include <libvdeplug.h>
+#include "slirpvde/tcp2unix.h"
 
 #if defined(VDE_DARWIN) || defined(VDE_FREEBSD)
 #	include <limits.h>

 If you’re more familiar with the vde project and see any issues with these patches feel free to post a comment about it.

Compiling and installing libraries/dependencies

Compiling the libraries is a short simple process. Begin by untarring the archive, in this case the patched version.
Next run the configure script, then make and make install commands as shown below.

./configure 
make
make install

The install will create files and directories under /usr/local. You can verify your vde libraries by listing the contents of the /usr/local/lib and /usr/local/lib/vde2 directories. It should look like the following.

ll /usr/local/lib
total 448
-rw-r--r-- 1 root root 78978 2008-08-18 14:24 libvdemgmt.a
-rwxr-xr-x 1 root root   841 2008-08-18 14:24 libvdemgmt.la
lrwxrwxrwx 1 root root    19 2008-08-18 14:24 libvdemgmt.so -> libvdemgmt.so.0.0.1
lrwxrwxrwx 1 root root    19 2008-08-18 14:24 libvdemgmt.so.0 -> libvdemgmt.so.0.0.1
-rwxr-xr-x 1 root root 57848 2008-08-18 14:24 libvdemgmt.so.0.0.1
-rw-r--r-- 1 root root 66772 2008-08-18 14:24 libvdeplug.a
-rwxr-xr-x 1 root root   841 2008-08-18 14:24 libvdeplug.la
lrwxrwxrwx 1 root root    19 2008-08-18 14:24 libvdeplug.so -> libvdeplug.so.2.1.0
lrwxrwxrwx 1 root root    19 2008-08-18 14:24 libvdeplug.so.2 -> libvdeplug.so.2.1.0
-rwxr-xr-x 1 root root 50745 2008-08-18 14:24 libvdeplug.so.2.1.0
-rw-r--r-- 1 root root 86722 2008-08-18 14:24 libvdesnmp.a
-rwxr-xr-x 1 root root   841 2008-08-18 14:24 libvdesnmp.la
lrwxrwxrwx 1 root root    19 2008-08-18 14:24 libvdesnmp.so -> libvdesnmp.so.0.0.1
lrwxrwxrwx 1 root root    19 2008-08-18 14:24 libvdesnmp.so.0 -> libvdesnmp.so.0.0.1
-rwxr-xr-x 1 root root 58874 2008-08-18 14:24 libvdesnmp.so.0.0.1
drwxr-xr-x 3 root root  4096 2008-08-18 14:24 vde2

 Below shows contents of /usr/local/lib/vde2

ll /usr/local/lib/vde2/
total 52
-rw-r--r-- 1 root root 22704 2008-08-18 14:24 libvdetap.a
-rwxr-xr-x 1 root root   830 2008-08-18 14:24 libvdetap.la
-rwxr-xr-x 1 root root 19982 2008-08-18 14:24 libvdetap.so
drwxr-xr-x 2 root root  4096 2008-08-18 14:24 vde_l3

Your libraries are now ready to be used natively by KVM.

Enabling KVM native support for VDE

Now that you have the vde libraries installed you can link the vde code directly into kvm when compiling your kvm module as outlined in this post about enabling vde support in kvm  . Note that patches have already been submitted to KVM so that in future versions beginning with KVM-73 there will be no need for using the –enable-vde flag such that vde will be enabled by default once the libraries are detected.