+%define version 20120610
+%define taglevel 2
+
+# when no planetlab kernel is being built, kernel_version is defined but empty
+%define _with_planetlab_kernel %{?kernel_version:1}%{!?kernel_version:0}
+# we need to make sure that this rpm gets upgraded when the kernel release changes
+%if %{_with_planetlab_kernel}
+# with the planetlab kernel
+%define pl_kernel_taglevel %( echo %{kernel_release} | cut -d. -f1 )
+%define ipfw_release %{kernel_version}.%{pl_kernel_taglevel}
+%else
+# with the stock kernel
+# this line below
+#%define ipfw_release %( rpm -q --qf "%{version}" kernel-headers )
+# causes recursive macro definition no matter how much you quote
+%define percent %
+%define braop \{
+%define bracl \}
+%define kernel_version %( rpm -q --qf %{percent}%{braop}version%{bracl} kernel-headers )
+%define kernel_release %( rpm -q --qf %{percent}%{braop}release%{bracl} kernel-headers )
+%define kernel_arch %( rpm -q --qf %{percent}%{braop}arch%{bracl} kernel-headers )
+%define ipfw_release %{kernel_version}.%{kernel_release}
+%endif
+
+%define release %{ipfw_release}.%{taglevel}%{?pldistro:.%{pldistro}}%{?date:.%{date}}