-Other than the Linux kernel module, the software in the OpenFlow
-distribution should compile under Unix-like environments such as
-Linux, FreeBSD, Mac OS X, and Solaris. Our primary test environment
-is Debian GNU/Linux. Please contact us with portability-related bug
-reports or patches.
+Other than the Linux kernel module and userspace switch
+implementation, the software in the OpenFlow distribution should
+compile under Unix-like environments such as Linux, FreeBSD, Mac OS X,
+and Solaris. Our primary test environment is Debian GNU/Linux.
+Please contact us with portability-related bug reports or patches.
+
+The Linux kernel module is, of course, Linux-specific, and the dpctl
+utility will not be useful without the kernel module. The testing of
+the kernel module has focused on Linux 2.6.26. Linux 2.6 releases
+from 2.6.15 onward and Linux 2.4 releases from 2.4.20 onward should
+also work.