(is_xen) enable to detect if we run under XEN
(should better check through cpuid...)

(hasCPU_virt_support) detect whether we've HW support for virt or not

(_is_kernelServer_supported) split it out of _is_kernelServer_needed()

(_bestKernelXEN_extensions) select kernel-server or kernel-xen-pvps
when running under XEN (depending on virt HW support presence)

(_bestKernel_extensions) use _bestKernelXEN_extensions() in order to
select the proper kernel for XEN

diff -up ./detect_devices.pm.tv ./detect_devices.pm
--- ./detect_devices.pm.tv	2012-01-09 10:33:40.946242888 +0100
+++ ./detect_devices.pm	2012-01-09 10:40:47.668522223 +0100
@@ -1213,6 +1213,10 @@ sub is_vmware() {
     any { $_->{driver} =~ /Card:VMware/ } detect_devices::pci_probe();
 }
 
+sub is_xen() {
+    -f '/proc/xen/capabilities';
+}
+
 sub is_netbook_nettop() {
     my @cpus = getCPUs();
     (any { $_->{'model name'} =~ /(\bIntel\(R\) Atom\(TM\)\B)/i } @cpus) ||
@@ -1254,6 +1258,10 @@ sub hasCPUMicrocode() {
     return $hasCPUMicrocode;
 }
 
+sub hasCPU_virt_support() {
+    has_cpu_flag('svm') || has_cpu_flag('vmx');
+}
+
 sub hasCPUFreq()     {
     require cpufreq;
      to_bool(cpufreq::get_modules())
diff -up ./install/pkgs.pm.tv ./install/pkgs.pm
--- ./install/pkgs.pm.tv	2012-01-09 10:30:32.527118304 +0100
+++ ./install/pkgs.pm	2012-01-09 10:44:48.727700307 +0100
@@ -105,12 +105,19 @@ sub packageByName {
     $best;
 }
 
-sub _is_kernelServer_needed() {
+sub _is_kernelServer_supported() {
     # forbid selecting kernel-server if not having PAE since PAE support is mandatory for kernel-server:
-    return if !detect_devices::has_cpu_flag('pae');
+    detect_devices::has_cpu_flag('pae');
+}
+sub _is_kernelServer_needed() {
+    return if !_is_kernelServer_supported();
     arch() =~ /i.86/ && detect_devices::dmi_detect_memory() > 3.8 * 1024 || detect_devices::isServer();
 }
 
+sub _bestKernelXEN_extensions() {
+    _is_kernelServer_supported() && detect_devices::hasCPU_virt_support() ? '-server' : '-xen-pvps';
+}
+
 sub _bestKernel_extensions {
     my ($o_match_all_hardware) = @_;
 
@@ -118,6 +125,7 @@ sub _bestKernel_extensions {
     $o_match_all_hardware ? (arch() =~ /i.86/ ? '-desktop586' : '-desktop') :
       detect_devices::is_xbox() ? '-xbox' :
       detect_devices::is_i586() ? '-desktop586' :
+      detect_devices::is_xen() ? _bestKernelXEN_extensions() :
       _is_kernelServer_needed() ? '-server' :
       '-desktop';
 }