Remove support for Xen PV domU kernels. Support for HVM domU kernels

remains.  Xen is planning to phase out support for PV upstream since it
is harder to maintain and has more overhead.  Modern x86 CPUs include
virtualization extensions that support HVM guests instead of PV guests.
In addition, the PV code was i386 only and not as well maintained recently
as the HVM code.
- Remove the i386-only NATIVE option that was used to disable certain
  components for PV kernels.  These components are now standard as they
  are on amd64.
- Remove !XENHVM bits from PV drivers.
- Remove various shims required for XEN (e.g. PT_UPDATES_FLUSH, LOAD_CR3,
  etc.)
- Remove duplicate copy of <xen/features.h>.
- Remove unused, i386-only xenstored.h.

Differential Revision:	https://reviews.freebsd.org/D2362
Reviewed by:	royger
Tested by:	royger (i386/amd64 HVM domU and amd64 PVH dom0)
Relnotes:	yes

1 files changed, 3 insertions, 36 deletions

diff --git a/share/man/man4/xen.4 b/share/man/man4/xen.4
index 2eea692..c2b1f5b 100644
--- a/share/man/man4/xen.4
+++ b/share/man/man4/xen.4
@@ -35,14 +35,6 @@
 .Nm xen
 .Nd Xen Hypervisor Guest (DomU) Support
 .Sh SYNOPSIS
-To compile para-virtualized (PV) Xen guest support into an i386 kernel, place
-the following lines in your kernel configuration file:
-.Bd -ragged -offset indent
-.Cd "options PAE"
-.Cd "options XEN"
-.Cd "nooptions NATIVE"
-.Ed
-.Pp
 To compile hardware-assisted virtualization (HVM) Xen guest support with
 para-virtualized drivers into an amd64 or i386 kernel,
 place the following lines in your kernel configuration file:
@@ -69,34 +61,14 @@ and hence able to optimize certain behaviors to improve performance or
 semantics.
 .Pp
 .Fx
-supports a fully para-virtualized (PV) kernel on the i386 architecture using
-.Cd "options XEN"
-and
-.Cd "nooptions NATIVE" ;
-currently, this requires use of a PAE kernel, enabled via
-.Cd "options PAE" .
-.Pp
-.Fx
-supports hardware-assisted virtualization (HVM) on both the i386 and amd64
-kernels; however, PV device drivers with an HVM kernel are only supported on
-the amd64 architecture, and require
-.Cd "options XENHVM"
-and
-.Cd "device xenpci" .
+supports hardware-assisted virtualization (HVM) on both i386 and amd64
+kernels.
 .Pp
 Para-virtualized device drivers are required in order to support certain
 functionality, such as processing management requests, returning idle
 physical memory pages to the hypervisor, etc.
 .Ss Xen DomU device drivers
-Xen para-virtualized drivers are automatically added to the kernel if a PV
-kernel is compiled using
-.Cd "options XEN" ;
-for HVM environments,
-.Cd "options XENHVM"
-and
-.Cd "device xenpci"
-are required.
-The follow drivers are supported:
+These para-virtualized drivers are supported:
 .Bl -hang -offset indent -width blkfront
 .It Nm balloon
 Allow physical memory pages to be returned to the hypervisor as a result of
@@ -148,8 +120,6 @@ It is recommended that adaptive locking be disabled when using Xen:
 .Cd "options NO_ADAPTIVE_RWLOCKS"
 .Cd "options NO_ADAPTIVE_SX"
 .Ed
-.Sh SEE ALSO
-.Xr pae 4
 .Sh HISTORY
 Support for
 .Nm
@@ -173,9 +143,6 @@ This manual page was written by
 .Fx
 is only able to run as a Xen guest (DomU) and not as a Xen host (Dom0).
 .Pp
-A fully para-virtualized (PV) kernel is only supported on i386, and not
-amd64.
-.Pp
 As of this release, Xen PV DomU support is not heavily tested; instability
 has been reported during VM migration of PV kernels.
 .Pp