[patch 14/24] Xen-paravirt_ops: Add XEN config options

[Jeremy Fitzhardinge <jeremy@goop.org>]

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The XEN config option enables the Xen paravirt_ops interface, which is
installed when the kernel finds itself running under Xen.

Xen is no longer a sub-architecture, so the X86_XEN subarch config
option has gone.

Xen is currently incompatible with:
- PREEMPT
- HZ: set to 100Hz for now, to cut down on VCPU context switch rate.
  This will be adapted to use tickless later.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

---
 arch/i386/Kconfig     |    2 ++
 arch/i386/xen/Kconfig |   10 ++++++++++
 2 files changed, 12 insertions(+)

===================================================================
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -216,6 +216,8 @@ config PARAVIRT
 	  under a hypervisor, improving performance significantly.
 	  However, when run without a hypervisor the kernel is
 	  theoretically slower.  If in doubt, say N.
+
+source "arch/i386/xen/Kconfig"
 
 config VMI
 	bool "VMI Paravirt-ops support"
===================================================================
--- /dev/null
+++ b/arch/i386/xen/Kconfig
@@ -0,0 +1,10 @@
+#
+# This Kconfig describes xen options
+#
+
+config XEN
+	bool "Enable support for Xen hypervisor"
+	depends on PARAVIRT && HZ_100 && !PREEMPT && !NO_HZ
+	default y
+	help
+	  This is the Linux Xen port.

--