[U-Boot] [PATCH v6 2/9] x86: Allow excluding reset vector code from u-boot

[Simon Glass]

From: Gabe Black <gabeblack at chromium.org>

When running from coreboot we don't want this code.

This version works by ifdef-ing out all of the code that would go
into those sections and all the code that refers to it. The sections are
then empty, and the linker will either leave them empty for the loader
to ignore or remove them entirely.

Signed-off-by: Gabe Black <gabeblack at chromium.org>
Signed-off-by: Simon Glass <sjg at chromium.org>
---
Changes in v6:
- Rename option to CONFIG_X86_NO_RESET_VECTOR
- Adjust Makefiles to deal with CONFIG_X86_NO_RESET_VECTOR

Changes in v5:
- Use CONFIG_NO_RESET_CODE again (as v3), check it in arch config.h

Changes in v4:
- Use CONFIG_SYS_X86_RESET_VECTOR instead CONFIG_NO_RESET_CODE
- Add note about CONFIG_SYS_X86_RESET_VECTOR to README

Changes in v3:
- Fix incorrect repeated line in Makefile

Changes in v2:
- Put CONFIG_NO_RESET_CODE into Makefile instead of source files

 Makefile                |    6 +++---
 README                  |    4 ++++
 arch/x86/cpu/Makefile   |    5 +++--
 arch/x86/cpu/u-boot.lds |    3 +++
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index 1a17be9..1d564b3 100644
--- a/Makefile
+++ b/Makefile
@@ -231,8 +231,8 @@ endif
 
 OBJS  = $(CPUDIR)/start.o
 ifeq ($(CPU),x86)
-OBJS += $(CPUDIR)/start16.o
-OBJS += $(CPUDIR)/resetvec.o
+RESET_OBJS-$(CONFIG_X86_NO_RESET_VECTOR) += $(CPUDIR)/start16.o
+RESET_OBJS-$(CONFIG_X86_NO_RESET_VECTOR) += $(CPUDIR)/resetvec.o
 endif
 ifeq ($(CPU),ppc4xx)
 OBJS += $(CPUDIR)/resetvec.o
@@ -241,7 +241,7 @@ ifeq ($(CPU),mpc85xx)
 OBJS += $(CPUDIR)/resetvec.o
 endif
 
-OBJS := $(addprefix $(obj),$(OBJS))
+OBJS := $(addprefix $(obj),$(OBJS) $(RESET_OBJS-))
 
 HAVE_VENDOR_COMMON_LIB = $(if $(wildcard board/$(VENDOR)/common/Makefile),y,n)
 
diff --git a/README b/README
index 2dc0984..163c109 100644
--- a/README
+++ b/README
@@ -3621,6 +3621,10 @@ Low Level (hardware related) configuration options:
 		be used if available. These functions may be faster under some
 		conditions but may increase the binary size.
 
+- CONFIG_X86_NO_RESET_VECTOR
+		If defined, the x86 reset vector code is excluded. You will need
+		to do this when U-Boot is running from Coreboot.
+
 Freescale QE/FMAN Firmware Support:
 -----------------------------------
 
diff --git a/arch/x86/cpu/Makefile b/arch/x86/cpu/Makefile
index 7f1fc18..be27dd9 100644
--- a/arch/x86/cpu/Makefile
+++ b/arch/x86/cpu/Makefile
@@ -28,12 +28,13 @@ include $(TOPDIR)/config.mk
 
 LIB	= $(obj)lib$(CPU).o
 
-START	= start.o start16.o resetvec.o
+START-y	= start.o
+RESET_OBJS-$(CONFIG_X86_NO_RESET_VECTOR) += resetvec.o start16.o
 COBJS	= interrupts.o cpu.o
 
 SRCS	:= $(START:.o=.S) $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS))
-START	:= $(addprefix $(obj),$(START))
+START	:= $(addprefix $(obj),$(START-y) $(RESET_OBJS-))
 
 all:	$(obj).depend $(START) $(LIB)
 
diff --git a/arch/x86/cpu/u-boot.lds b/arch/x86/cpu/u-boot.lds
index a1ecefa..0c6f0e3 100644
--- a/arch/x86/cpu/u-boot.lds
+++ b/arch/x86/cpu/u-boot.lds
@@ -86,6 +86,8 @@ SECTIONS
 	__bios_start = LOADADDR(.bios);
 	__bios_size = SIZEOF(.bios);
 
+#ifndef CONFIG_X86_NO_RESET_VECTOR
+
 	/*
 	 * The following expressions place the 16-bit Real-Mode code and
 	 * Reset Vector at the end of the Flash ROM
@@ -95,4 +97,5 @@ SECTIONS
 
 	. = RESET_VEC_LOC;
 	.resetvec : AT (CONFIG_SYS_TEXT_BASE + (CONFIG_SYS_MONITOR_LEN - RESET_SEG_SIZE + RESET_VEC_LOC)) { KEEP(*(.resetvec)); }
+#endif
 }
-- 
1.7.7.3