On 1/29/16 12:20 PM, Andrew Cooper wrote:
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Doug Goldstein <cardoe@cardoe.com>
> CC: Tim Deegan <tim@xen.org>
> CC: George Dunlap <george.dunlap@eu.citrix.com>
> 
> v2:
>  * Expand text.  Use more-common makefile syntax
> ---
>  xen/arch/x86/Kconfig            | 18 ++++++++++++++++++
>  xen/arch/x86/Rules.mk           |  4 ----
>  xen/arch/x86/mm/shadow/Makefile |  2 +-
>  3 files changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
> index 4781b34..1fd72fa 100644
> --- a/xen/arch/x86/Kconfig
> +++ b/xen/arch/x86/Kconfig
> @@ -27,6 +27,24 @@ menu "Architecture Features"
>  
>  source "arch/Kconfig"
>  
> +config SHADOW_PAGING
> +        bool "Shadow Paging"
> +        default y
> +        ---help---
> +
> +          Shadow paging is a software alternative to hardware paging support
> +          (Intel EPT, AMD NPT).
> +
> +          It is required for:
> +            * Running HVM guests on hardware lacking hardware paging support
> +              (First-generation Intel VT-x or AMD SVM).
> +            * Live migration of PV guests.
> +
> +          Under a small number of specific workloads, shadow paging may be
> +          deliberately used as a performance optimisation.
> +
> +          If unsure, say Y.
> +
>  config BIGMEM
>  	bool "big memory support"
>  	default n
> diff --git a/xen/arch/x86/Rules.mk b/xen/arch/x86/Rules.mk
> index a108d24..a1cdae0 100644
> --- a/xen/arch/x86/Rules.mk
> +++ b/xen/arch/x86/Rules.mk
> @@ -22,13 +22,9 @@ $(call as-insn-check,CFLAGS,CC,".equ \"x\"$$(comma)1", \
>                       -U__OBJECT_LABEL__ -DHAVE_GAS_QUOTED_SYM \
>                       '-D__OBJECT_LABEL__=$(subst $(BASEDIR)/,,$(CURDIR))/$$@')
>  
> -shadow-paging ?= y
> -
>  CFLAGS += -mno-red-zone -mno-sse -fpic
>  CFLAGS += -fno-asynchronous-unwind-tables
>  # -fvisibility=hidden reduces -fpic cost, if it's available
>  ifneq ($(call cc-option,$(CC),-fvisibility=hidden,n),n)
>  CFLAGS += -DGCC_HAS_VISIBILITY_ATTRIBUTE
>  endif
> -
> -CFLAGS-$(shadow-paging) += -DCONFIG_SHADOW_PAGING
> diff --git a/xen/arch/x86/mm/shadow/Makefile b/xen/arch/x86/mm/shadow/Makefile
> index a07bc0c..cd4ec8a 100644
> --- a/xen/arch/x86/mm/shadow/Makefile
> +++ b/xen/arch/x86/mm/shadow/Makefile
> @@ -1,4 +1,4 @@
> -ifeq ($(shadow-paging),y)
> +ifeq ($(CONFIG_SHADOW_PAGING),y)
>  obj-y += common.o guest_2.o guest_3.o guest_4.o
>  else
>  obj-y += none.o
> 

Reviewed-by: Doug Goldstein <cardoe@cardoe.com>

-- 
Doug Goldstein