build system: Exempt make *config from strict symbol checks

The "config" targets exist to edit the .config file, and so they
should be more forgiving with invalid configs (that they'll convert
into valid configs on save). They will still emit warnings about
invalid symbols, but not exit with an error.

The regular build process still fails if the .config looks unexpected
(for example when there's an unknown config flag).

Change-Id: If427e075766c68d493dd406609f21b6bb27d1d74
Signed-off-by: Patrick Georgi <patrick@coreboot.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79298
Reviewed-by: Mike Banon <mikebdp2@gmail.com>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>

Makefile

@@ -29,14 +29,17 @@ KCONFIG_DEPENDENCIES := $(obj)/auto.conf.cmd
 KCONFIG_SPLITCONFIG := $(obj)/config/
 KCONFIG_TRISTATE := $(obj)/tristate.conf
 KCONFIG_NEGATIVES := 1
-KCONFIG_WERROR:= 1
-KCONFIG_WARN_UNKNOWN_SYMBOLS:= 1
+KCONFIG_WERROR := 1
+KCONFIG_WARN_UNKNOWN_SYMBOLS := 1
 KCONFIG_PACKAGE := CB.Config
 KCONFIG_MAKEFILE_REAL ?= $(objk)/Makefile.real
 
 COREBOOT_EXPORTS += KCONFIG_CONFIG KCONFIG_AUTOHEADER KCONFIG_AUTOCONFIG
 COREBOOT_EXPORTS += KCONFIG_DEPENDENCIES KCONFIG_SPLITCONFIG KCONFIG_TRISTATE
-COREBOOT_EXPORTS += KCONFIG_NEGATIVES KCONFIG_WERROR
+COREBOOT_EXPORTS += KCONFIG_NEGATIVES
+ifeq ($(filter %config,$(MAKECMDGOALS)),)
+COREBOOT_EXPORTS += KCONFIG_WERROR
+endif
 COREBOOT_EXPORTS += KCONFIG_WARN_UNKNOWN_SYMBOLS
 COREBOOT_EXPORTS += KCONFIG_AUTOADS KCONFIG_PACKAGE
 

util/kconfig/Makefile.inc

@@ -47,8 +47,6 @@ unexport KCONFIG_DEFCONFIG_LIST
 
 # Fill in Linux kconfig build rules to work
 
-oldconfig: KCONFIG_STRICT=
-
 savedefconfig: $(objk)/conf
 	cp $(DOTCONFIG) $(DEFCONFIG)
 	chmod +w $(DEFCONFIG)