[U-Boot] [PATCH v5 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 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                      |    8 +++-----
 README                        |    4 ++++
 arch/x86/cpu/Makefile         |    5 +++--
 arch/x86/cpu/u-boot.lds       |    3 +++
 arch/x86/include/asm/config.h |    5 +++++
 5 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/Makefile b/Makefile
index 1a17be9..dcd3a0c 100644
--- a/Makefile
+++ b/Makefile
@@ -230,10 +230,8 @@ endif
 # U-Boot objects....order is important (i.e. start must be first)
 
 OBJS  = $(CPUDIR)/start.o
-ifeq ($(CPU),x86)
-OBJS += $(CPUDIR)/start16.o
-OBJS += $(CPUDIR)/resetvec.o
-endif
+OBJS-$(CONFIG_SYS_X86_RESET_VECTOR) += $(CPUDIR)/start16.o
+OBJS-$(CONFIG_SYS_X86_RESET_VECTOR) += $(CPUDIR)/resetvec.o
 ifeq ($(CPU),ppc4xx)
 OBJS += $(CPUDIR)/resetvec.o
 endif
@@ -241,7 +239,7 @@ ifeq ($(CPU),mpc85xx)
 OBJS += $(CPUDIR)/resetvec.o
 endif
 
-OBJS := $(addprefix $(obj),$(OBJS))
+OBJS := $(addprefix $(obj),$(OBJS) $(OBJS-y))
 
 HAVE_VENDOR_COMMON_LIB = $(if $(wildcard board/$(VENDOR)/common/Makefile),y,n)
 
diff --git a/README b/README
index 2dc0984..dd7fb9d 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_NO_RESET_CODE
+		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..b0c350c 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
+START-$(CONFIG_SYS_X86_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))
 
 all:	$(obj).depend $(START) $(LIB)
 
diff --git a/arch/x86/cpu/u-boot.lds b/arch/x86/cpu/u-boot.lds
index a1ecefa..de6dfdc 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);
 
+#ifdef CONFIG_SYS_X86_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
 }
diff --git a/arch/x86/include/asm/config.h b/arch/x86/include/asm/config.h
index 049c44e..e3cae0b 100644
--- a/arch/x86/include/asm/config.h
+++ b/arch/x86/include/asm/config.h
@@ -21,4 +21,9 @@
 #ifndef _ASM_CONFIG_H_
 #define _ASM_CONFIG_H_
 
+/* Include the reset fector code unless the board configure doesn't want it */
+#ifndef CONFIG_NO_RESET_CODE
+#define CONFIG_SYS_X86_RESET_VECTOR
+#endif
+
 #endif
-- 
1.7.7.3