--- wikisrc/ports/xen/howto.mdwn	2020/04/03 10:48:35	1.168
+++ wikisrc/ports/xen/howto.mdwn	2020/10/31 16:33:14	1.171
@@ -8,21 +8,28 @@ systems which operate in an unprivileged
 from the domU systems are forwarded by the Xen hypervisor to the dom0 to be
 fulfilled.
 
-Xen supports different styles of guest:
+Xen supports different styles of guests; see https://wiki.xen.org/wiki/PV_on_HVM and https://wiki.xenproject.org/wiki/PVH_(v2)_Domu for upstream documentation.
 
 [[!table data="""
 Style of guest	|Supported by NetBSD
 PV		|Yes (dom0, domU)
 HVM		|Yes (domU)
-PVHVM		|No
-PVH		|No
+PVH		|current-only (domU, dom0 not yet)
+PVHVM		|current-only (domU)
 """]]
 
 In Para-Virtualized (PV) mode, the guest OS does not attempt to access
 hardware directly, but instead makes hypercalls to the hypervisor; PV
-guests must be specifically coded for Xen. In HVM mode, no guest
-modification is required; however, hardware support is required, such
-as VT-x on Intel CPUs and SVM on AMD CPUs.
+guests must be specifically coded for Xen.
+
+In HVM mode, no guest modification is required; however, hardware
+support is required, such as VT-x on Intel CPUs and SVM on AMD CPUs.
+
+In PVH mode, the guest uses PV interfaces for IO and native interfaces for everything else.
+
+In PVHVM mode, the guest mostly runs as HVM, but can use PV drivers for efficiency.
+
+\todo Explain about "HVM with PV drivers".
 
 At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
 The dom0 can start one or more domUs.  (Booting is explained in detail
@@ -337,7 +344,7 @@ will trigger controlled shutdowns of all
 CPU and memory
 --------------
 
-A domain is provided with some number of vcpus, less than the number
+A domain is provided with some number of vcpus, up to the number
 of CPUs seen by the hypervisor. For a domU, it is controlled
 from the config file by the "vcpus = N" directive.