Kconfig: Add an option to skip adding a cbfs bootblock on x86

Some targets don't need this as the bootblock is loaded differently.

Change-Id: Ia42448f7e9dd0635c72857fbc1fab54508932721
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63377
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/Kconfig

@@ -1327,6 +1327,12 @@ config BOOTBLOCK_CUSTOM
 	# src/lib/bootblock.c#main() C entry point.
 	bool
 
+config BOOTBLOCK_IN_CBFS
+	bool
+	default y if ARCH_X86
+	help
+	  Select this on platforms that have a top aligned bootblock inside cbfs.
+
 config MEMLAYOUT_LD_FILE
 	string
 	default "src/mainboard/\$(CONFIG_MAINBOARD_DIR)/memlayout.ld"

src/arch/x86/Makefile.inc

@@ -101,11 +101,13 @@ $(eval $(call early_x86_stage,bootblock,elf64-x86-64))
 endif
 
 ifneq ($(CONFIG_UPDATE_IMAGE),y)
+ifeq ($(CONFIG_BOOTBLOCK_IN_CBFS),y)
 $(call add_intermediate, add_bootblock, $(objcbfs)/bootblock.bin)
 	@printf "    CBFS       $(subst $(obj)/,,$(@))\n"
 	$(CBFSTOOL) $< add -f $(objcbfs)/bootblock.bin  -n bootblock -t bootblock $(TXTIBB) -b -$(call file-size,$(objcbfs)/bootblock.bin) \
 	$(cbfs-autogen-attributes) $(TS_OPTIONS) $(CBFSTOOL_ADD_CMD_OPTIONS)
 endif
+endif
 
 $(call src-to-obj,bootblock,$(dir)/walkcbfs.S): $(obj)/fmap_config.h
 bootblock-y += walkcbfs.S

src/lib/master_header_pointer.c

@@ -5,7 +5,7 @@
 #include <fmap_config.h>
 #include <stdint.h>
 
-#if ENV_X86
+#if CONFIG(BOOTBLOCK_IN_CBFS)
 __attribute__((used, __section__(".header_pointer")))
 #endif