x86, platform, kconfig: move kvmconfig functionality to a helper

The new mergeconfig helper makes it easier to add other partial
configurations similar to kvmconfig.  Architecture-independent portions
of those partial configurations should go in
kernel/configs/${name}.config, and architecture-dependent portions
should go in arch/${arch}/configs/${name}.config.

Based on a patch by Luis R. Rodriguez <mcgrof@suse.com>.
Originally-Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>

Modified to make the helper name more general than just virtualization,
support architecture-dependent and architecture-independent partial
configurations, move the helper and kvmconfig to
scripts/kconfig/Makefile, and factor out more of the common file path.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
index 9c4d2412fb72..8083b94b45ee 100644
--- a/scripts/kconfig/Makefile
+++ b/scripts/kconfig/Makefile
@@ -104,6 +104,19 @@ endif
 %_defconfig: $(obj)/conf
         $(Q)$< --defconfig=arch/$(SRCARCH)/configs/$@ $(Kconfig)
 
+configfiles=$(wildcard $(srctree)/kernel/configs/$(1).config $(srctree)/arch/$(SRCARCH)/configs/$(1).config)
+
+define mergeconfig
+$(if $(wildcard $(objtree)/.config),, $(error You need an existing .config for this target))
+$(if $(call configfiles,$(1)),, $(error No configuration exists for this target on this architecture))
+$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh -m -O $(objtree) $(objtree)/.config $(call configfiles,$(1))
+$(Q)yes "" | $(MAKE) -f $(srctree)/Makefile oldconfig
+endef
+
+PHONY += kvmconfig
+kvmconfig:
+        $(call mergeconfig,kvm_guest)
+
 # Help text used by make help
 help:
         @echo  '  config          - Update current config utilising a line-oriented program'
@@ -124,6 +137,7 @@ help:
         @echo  '  randconfig      - New config with random answer to all options'
         @echo  '  listnewconfig   - List new options'
         @echo  '  olddefconfig    - Same as silentoldconfig but sets new symbols to their default value'
+        @echo  '  kvmconfig       - Enable additional options for guest kernel support'
 
 # lxdialog stuff
 check-lxdialog  := $(srctree)/$(src)/lxdialog/check-lxdialog.sh