[Xen-devel] [PATCH] x86: Convert shadow-paging to Kconfig

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Doug Goldstein <cardoe@xxxxxxxxxx>
CC: Tim Deegan <tim@xxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

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
-- 
2.1.4


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