[PATCH 1/3] Virtualization config cleanup: Select CONFIG_PARAVIRTwhen required

From: Rusty Russell
Date: Mon Sep 24 2007 - 23:59:01 EST


(Unless there are complaints, I'll push this as part of the lguest
patches for 2.6.24, since there are lguest config changes there too).

Andi points out that PARAVIRT is an option best selected when needed.

We introduce PARAVIRT_GUEST for the menu itself, and select PARAVIRT
if the user turns on anything which needs it.

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
arch/i386/Kconfig | 33 ++++++++++++++++++++-------------
arch/i386/xen/Kconfig | 1 +
2 files changed, 21 insertions(+), 13 deletions(-)

===================================================================
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -214,24 +214,30 @@ config X86_ES7000

endchoice

-menuconfig PARAVIRT
+config PARAVIRT
+ bool
+ depends on !(X86_VISWS || X86_VOYAGER)
+ help
+ This changes the kernel so it can modify itself when it is run
+ under a hypervisor, potentially improving performance significantly
+ over full virtualization. However, when run without a hypervisor
+ the kernel is theoretically slower and slightly larger.
+
+menuconfig PARAVIRT_GUEST
- bool "Paravirtualized guest support (EXPERIMENTAL)"
- depends on EXPERIMENTAL
+ bool "Paravirtualized guest support"
- depends on !(X86_VISWS || X86_VOYAGER)
- help
- Paravirtualization is a way of running multiple instances of
- Linux on the same machine, under a hypervisor. This option
- changes the kernel so it can modify itself when it is run
- under a hypervisor, improving performance significantly.
- However, when run without a hypervisor the kernel is
- theoretically slower. If in doubt, say N.
-
-if PARAVIRT
+ help
+ Say Y here to get to see options related to running Linux under
+ various hypervisors. This option alone does not add any kernel code.
+
+ If you say N, all options in this submenu will be skipped and disabled.
+
+if PARAVIRT_GUEST

source "arch/i386/xen/Kconfig"

config VMI
bool "VMI Guest support"
+ select PARAVIRT
help
VMI provides a paravirtualized interface to the VMware ESX server
(it could be used by other hypervisors in theory too, but is not
@@ -239,6 +246,7 @@ config VMI

config LGUEST_GUEST
bool "Lguest guest support"
+ select PARAVIRT
depends on !X86_PAE
help
Lguest is a tiny in-kernel hypervisor. Selecting this will
===================================================================
--- a/arch/i386/xen/Kconfig
+++ b/arch/i386/xen/Kconfig
@@ -4,6 +4,7 @@

config XEN
bool "Xen guest support"
+ select PARAVIRT
depends on X86_CMPXCHG && X86_TSC && !NEED_MULTIPLE_NODES
help
This is the Linux Xen port. Enabling this will allow the


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