[U-Boot] [PATCH] common: Link with GCC instead of LD
Flip over from linking with LD to linking with GCC. This has some long-term benefits, like easy path to enabling LTO.
Most of this patch is about passing parameters to the linker invoked by GCC at the linking stage. This involves prefixing most of these with -Wl,<param> . A few more adjustments had to be made though.
The LDFLAGS had to be extended by --build-id=none to prevent generation of the .note.gnu.build-id section, which contains unique build-id we don't care about. Moreover -nostdlib had to be added to LDFLAGS to link properly without pulling in GCC libs during partial link.
The LDFLAGS_FINAL had to be augmented by -Wl,-allow-multiple-definition to prevent GCC from complaining about multiple definitions of the register containing global data.
Signed-off-by: Marek Vasut marex@denx.de Cc: Albert Aribaud albert.u.boot@aribaud.net Cc: Joe Hershberger joe.hershberger@ni.com Cc: Mike Frysinger vapier@gentoo.org Cc: Tom Rini trini@ti.com Cc: Wolfgang Denk wd@denx.de --- Makefile | 4 ++-- arch/avr32/config.mk | 2 +- arch/blackfin/config.mk | 4 ++-- arch/m68k/config.mk | 4 ++-- arch/m68k/cpu/mcf5445x/config.mk | 2 +- arch/m68k/cpu/mcf547x_8x/config.mk | 2 +- arch/mips/config.mk | 4 ++-- arch/mips/cpu/mips64/config.mk | 4 ++-- arch/nds32/config.mk | 2 +- arch/nios2/config.mk | 2 +- arch/powerpc/config.mk | 2 +- arch/sh/config.mk | 4 ++-- arch/x86/config.mk | 8 ++++---- board/ait/cam_enc_4xx/config.mk | 2 +- config.mk | 15 +++++++-------- examples/standalone/Makefile | 4 ++-- nand_spl/board/amcc/acadia/Makefile | 2 +- nand_spl/board/amcc/bamboo/Makefile | 2 +- nand_spl/board/amcc/canyonlands/Makefile | 2 +- nand_spl/board/amcc/kilauea/Makefile | 2 +- nand_spl/board/amcc/sequoia/Makefile | 2 +- nand_spl/board/freescale/mpc8313erdb/Makefile | 2 +- nand_spl/board/freescale/mpc8315erdb/Makefile | 2 +- nand_spl/board/freescale/mpc8536ds/Makefile | 2 +- nand_spl/board/freescale/mpc8569mds/Makefile | 2 +- nand_spl/board/freescale/mpc8572ds/Makefile | 2 +- nand_spl/board/freescale/mx31pdk/Makefile | 2 +- nand_spl/board/freescale/p1010rdb/Makefile | 2 +- nand_spl/board/freescale/p1023rds/Makefile | 2 +- nand_spl/board/freescale/p1_p2_rdb/Makefile | 2 +- nand_spl/board/freescale/p1_p2_rdb_pc/Makefile | 2 +- nand_spl/board/karo/tx25/Makefile | 2 +- nand_spl/board/samsung/smdk6400/Makefile | 2 +- nand_spl/board/sheldon/simpc8313/Makefile | 2 +- spl/Makefile | 4 ++-- 35 files changed, 52 insertions(+), 53 deletions(-)
NOTE: It should mostly work, but _PLEASE_ test it properly. I definitelly can not run it on most of the affected platforms. Besides, it might still hit some build issues, it's not properly compiler-tested. Any additional fixes are welcome ;-)
NOTE: I detected code size being smaller by a few bytes, but then it might cause breakage, so I'd be really cautious here.
diff --git a/Makefile b/Makefile index 2fe1490..d6b3433 100644 --- a/Makefile +++ b/Makefile @@ -539,8 +539,8 @@ GEN_UBOOT = \ sed -n -e 's/.*($(SYM_PREFIX)_u_boot_list_.*)/-u\1/p'|sort|uniq`;\ cd $(LNDIR) && $(LD) $(LDFLAGS) $(LDFLAGS_$(@F)) \ $$UNDEF_LST $(__OBJS) \ - --start-group $(__LIBS) --end-group $(PLATFORM_LIBS) \ - -Map u-boot.map -o u-boot + -Wl,--start-group $(__LIBS) -Wl,--end-group \ + $(PLATFORM_LIBS) -Wl,-Map -Wl,u-boot.map -o u-boot endif
$(obj)u-boot: depend \ diff --git a/arch/avr32/config.mk b/arch/avr32/config.mk index a751a3d..151f232 100644 --- a/arch/avr32/config.mk +++ b/arch/avr32/config.mk @@ -28,4 +28,4 @@ CONFIG_STANDALONE_LOAD_ADDR ?= 0x00000000 PLATFORM_RELFLAGS += -ffixed-r5 -fPIC -mno-init-got -mrelax PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections
-LDFLAGS_u-boot = --gc-sections --relax +LDFLAGS_u-boot = -Wl,--gc-sections -Wl,--relax diff --git a/arch/blackfin/config.mk b/arch/blackfin/config.mk index 3595aa2..cbfba5f 100644 --- a/arch/blackfin/config.mk +++ b/arch/blackfin/config.mk @@ -37,8 +37,8 @@ CONFIG_BFIN_BOOT_MODE := $(strip $(subst ",,$(CONFIG_BFIN_BOOT_MODE))) PLATFORM_RELFLAGS += -ffixed-P3 -fomit-frame-pointer -mno-fdpic PLATFORM_CPPFLAGS += -DCONFIG_BLACKFIN
-LDFLAGS_FINAL += --gc-sections -LDFLAGS += -m elf32bfin +LDFLAGS_FINAL += -Wl,--gc-sections +LDFLAGS += -Wl,-m elf32bfin PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections
PLATFORM_RELFLAGS += -mcpu=$(CONFIG_BFIN_CPU) diff --git a/arch/m68k/config.mk b/arch/m68k/config.mk index 11ba334..2e5adb9 100644 --- a/arch/m68k/config.mk +++ b/arch/m68k/config.mk @@ -26,6 +26,6 @@ CROSS_COMPILE ?= m68k-elf- CONFIG_STANDALONE_LOAD_ADDR ?= 0x20000
PLATFORM_CPPFLAGS += -DCONFIG_M68K -D__M68K__ -PLATFORM_LDFLAGS += -n +PLATFORM_LDFLAGS += -Wl,-n PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections -LDFLAGS_FINAL += --gc-sections +LDFLAGS_FINAL += -Wl,--gc-sections diff --git a/arch/m68k/cpu/mcf5445x/config.mk b/arch/m68k/cpu/mcf5445x/config.mk index 0c48783..bd216a9 100644 --- a/arch/m68k/cpu/mcf5445x/config.mk +++ b/arch/m68k/cpu/mcf5445x/config.mk @@ -38,6 +38,6 @@ endif
ifneq (,$(findstring -linux-,$(shell $(CC) --version))) ifneq (,$(findstring GOT,$(shell $(LD) --help))) -PLATFORM_LDFLAGS += --got=single +PLATFORM_LDFLAGS += -Wl,--got=single endif endif diff --git a/arch/m68k/cpu/mcf547x_8x/config.mk b/arch/m68k/cpu/mcf547x_8x/config.mk index 02fce5d..00907d3 100644 --- a/arch/m68k/cpu/mcf547x_8x/config.mk +++ b/arch/m68k/cpu/mcf547x_8x/config.mk @@ -28,6 +28,6 @@ PLATFORM_CPPFLAGS += -mcpu=5485 -fPIC
ifneq (,$(findstring -linux-,$(shell $(CC) --version))) ifneq (,$(findstring GOT,$(shell $(LD) --help))) -PLATFORM_LDFLAGS += --got=single +PLATFORM_LDFLAGS += -Wl,--got=single endif endif diff --git a/arch/mips/config.mk b/arch/mips/config.mk index de9140b..c21d313 100644 --- a/arch/mips/config.mk +++ b/arch/mips/config.mk @@ -63,6 +63,6 @@ PLATFORM_CPPFLAGS += -DCONFIG_MIPS -D__MIPS__ # PLATFORM_CPPFLAGS += -G 0 -mabicalls -fpic $(ENDIANNESS) PLATFORM_CPPFLAGS += -msoft-float -PLATFORM_LDFLAGS += -G 0 -static -n -nostdlib $(ENDIANNESS) +PLATFORM_LDFLAGS += -G 0 -static -Wl,-n $(ENDIANNESS) PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections -LDFLAGS_FINAL += --gc-sections +LDFLAGS_FINAL += -Wl,--gc-sections diff --git a/arch/mips/cpu/mips64/config.mk b/arch/mips/cpu/mips64/config.mk index ebc1ceb..d9fbf27 100644 --- a/arch/mips/cpu/mips64/config.mk +++ b/arch/mips/cpu/mips64/config.mk @@ -32,9 +32,9 @@ MIPSFLAGS = -march=mips64 PLATFORM_CPPFLAGS += $(MIPSFLAGS) PLATFORM_CPPFLAGS += -mabi=64 -DCONFIG_64BIT ifdef CONFIG_SYS_BIG_ENDIAN -PLATFORM_LDFLAGS += -m elf64btsmip +PLATFORM_LDFLAGS += -Wl,-m elf64btsmip else -PLATFORM_LDFLAGS += -m elf64ltsmip +PLATFORM_LDFLAGS += -Wl,-m elf64ltsmip endif
CONFIG_STANDALONE_LOAD_ADDR ?= 0xffffffff80200000 -T mips64.lds diff --git a/arch/nds32/config.mk b/arch/nds32/config.mk index c589829..eccd2e6 100644 --- a/arch/nds32/config.mk +++ b/arch/nds32/config.mk @@ -32,4 +32,4 @@ PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -mrelax PLATFORM_RELFLAGS += -gdwarf-2 PLATFORM_CPPFLAGS += -DCONFIG_NDS32 -D__nds32__ -G0 -ffixed-10 -fpie
-LDFLAGS_u-boot = --gc-sections --relax +LDFLAGS_u-boot = -Wl,--gc-sections -Wl,--relax diff --git a/arch/nios2/config.mk b/arch/nios2/config.mk index 7b03ed8..9f9f6ac 100644 --- a/arch/nios2/config.mk +++ b/arch/nios2/config.mk @@ -29,5 +29,5 @@ CONFIG_STANDALONE_LOAD_ADDR ?= 0x02000000 PLATFORM_CPPFLAGS += -DCONFIG_NIOS2 -D__NIOS2__ PLATFORM_CPPFLAGS += -G0
-LDFLAGS_FINAL += --gc-sections +LDFLAGS_FINAL += -Wl,--gc-sections PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections diff --git a/arch/powerpc/config.mk b/arch/powerpc/config.mk index a307154..87e4934 100644 --- a/arch/powerpc/config.mk +++ b/arch/powerpc/config.mk @@ -24,7 +24,7 @@ CROSS_COMPILE ?= ppc_8xx-
CONFIG_STANDALONE_LOAD_ADDR ?= 0x40000 -LDFLAGS_FINAL += --gc-sections +LDFLAGS_FINAL += -Wl,--gc-sections PLATFORM_RELFLAGS += -fpic -mrelocatable -ffunction-sections -fdata-sections PLATFORM_CPPFLAGS += -DCONFIG_PPC -D__powerpc__ PLATFORM_LDFLAGS += -n diff --git a/arch/sh/config.mk b/arch/sh/config.mk index 07ff8b9..3451223 100644 --- a/arch/sh/config.mk +++ b/arch/sh/config.mk @@ -29,5 +29,5 @@ CONFIG_STANDALONE_LOAD_ADDR += -EB endif
PLATFORM_CPPFLAGS += -DCONFIG_SH -D__SH__ -PLATFORM_LDFLAGS += -e $(CONFIG_SYS_TEXT_BASE) --defsym reloc_dst=$(CONFIG_SYS_TEXT_BASE) -LDFLAGS_FINAL = --gc-sections +PLATFORM_LDFLAGS += -Wl,-e $(CONFIG_SYS_TEXT_BASE) -Wl,--defsym reloc_dst=$(CONFIG_SYS_TEXT_BASE) +LDFLAGS_FINAL = -Wl,--gc-sections diff --git a/arch/x86/config.mk b/arch/x86/config.mk index 23cacff..b3b07cc 100644 --- a/arch/x86/config.mk +++ b/arch/x86/config.mk @@ -38,11 +38,11 @@ PLATFORM_CPPFLAGS += -DREALMODE_BASE=0x7c0
PLATFORM_RELFLAGS += -ffunction-sections -fvisibility=hidden
-PLATFORM_LDFLAGS += --emit-relocs -Bsymbolic -Bsymbolic-functions +PLATFORM_LDFLAGS += -Wl,--emit-relocs -Wl,-Bsymbolic -Wl,-Bsymbolic-functions
-LDFLAGS_FINAL += --gc-sections -pie -LDFLAGS_FINAL += --wrap=__divdi3 --wrap=__udivdi3 -LDFLAGS_FINAL += --wrap=__moddi3 --wrap=__umoddi3 +LDFLAGS_FINAL += -Wl,--gc-sections -pie +LDFLAGS_FINAL += -Wl,--wrap=__divdi3 -Wl,--wrap=__udivdi3 +LDFLAGS_FINAL += -Wl,--wrap=__moddi3 -Wl,--wrap=__umoddi3
NORMAL_LIBGCC = $(shell $(CC) $(CFLAGS) -print-libgcc-file-name) PREFIXED_LIBGCC = $(OBJTREE)/arch/$(ARCH)/lib/$(shell basename $(NORMAL_LIBGCC)) diff --git a/board/ait/cam_enc_4xx/config.mk b/board/ait/cam_enc_4xx/config.mk index 744b927..0792c84 100644 --- a/board/ait/cam_enc_4xx/config.mk +++ b/board/ait/cam_enc_4xx/config.mk @@ -18,5 +18,5 @@ else # the following error message: # arm-linux-ld: u-boot-spl: Not enough room for program headers, try linking # with -N -LDFLAGS_u-boot-spl += -n +LDFLAGS_u-boot-spl += -Wl,-n endif diff --git a/config.mk b/config.mk index b7cd481..ec8cd6b 100644 --- a/config.mk +++ b/config.mk @@ -137,9 +137,8 @@ binutils-version = $(shell $(SHELL) $(SRCTREE)/tools/binutils-version.sh $(AS)) # AS = $(CROSS_COMPILE)as
-# Always use GNU ld -LD = $(shell if $(CROSS_COMPILE)ld.bfd -v > /dev/null 2>&1; \ - then echo "$(CROSS_COMPILE)ld.bfd"; else echo "$(CROSS_COMPILE)ld"; fi;) +# Link with GCC +LD = $(CROSS_COMPILE)gcc
CC = $(CROSS_COMPILE)gcc CPP = $(CC) -E @@ -202,7 +201,7 @@ CPPFLAGS := $(DBGFLAGS) $(OPTFLAGS) $(RELFLAGS) \ # Enable garbage collection of un-used sections for SPL ifeq ($(CONFIG_SPL_BUILD),y) CPPFLAGS += -ffunction-sections -fdata-sections -LDFLAGS_FINAL += --gc-sections +LDFLAGS_FINAL += -Wl,--gc-sections -Wl,--build-id=none endif
ifneq ($(CONFIG_SYS_TEXT_BASE),) @@ -265,17 +264,17 @@ endif
AFLAGS := $(AFLAGS_DEBUG) -D__ASSEMBLY__ $(CPPFLAGS)
-LDFLAGS += $(PLATFORM_LDFLAGS) -LDFLAGS_FINAL += -Bstatic +LDFLAGS += $(PLATFORM_LDFLAGS) -Wl,--build-id=none -nostdlib +LDFLAGS_FINAL += -Wl,-Bstatic -Wl,-allow-multiple-definition
LDFLAGS_u-boot += -T $(obj)u-boot.lds $(LDFLAGS_FINAL) ifneq ($(CONFIG_SYS_TEXT_BASE),) -LDFLAGS_u-boot += -Ttext $(CONFIG_SYS_TEXT_BASE) +LDFLAGS_u-boot += -Wl,-Ttext -Wl,$(CONFIG_SYS_TEXT_BASE) endif
LDFLAGS_u-boot-spl += -T $(obj)u-boot-spl.lds $(LDFLAGS_FINAL) ifneq ($(CONFIG_SPL_TEXT_BASE),) -LDFLAGS_u-boot-spl += -Ttext $(CONFIG_SPL_TEXT_BASE) +LDFLAGS_u-boot-spl += -Wl,-Ttext -Wl,$(CONFIG_SPL_TEXT_BASE) endif
# Linus' kernel sanity checking tool diff --git a/examples/standalone/Makefile b/examples/standalone/Makefile index baaa2fb..eaf8bb3 100644 --- a/examples/standalone/Makefile +++ b/examples/standalone/Makefile @@ -96,8 +96,8 @@ $(LIB): $(obj).depend $(LIBOBJS)
$(ELF): $(obj)%: $(obj)%.o $(LIB) - $(LD) $(LDFLAGS) -g -Ttext $(CONFIG_STANDALONE_LOAD_ADDR) \ - -o $@ -e $(SYM_PREFIX)$(notdir $(<:.o=)) $< $(LIB) \ + $(LD) $(LDFLAGS) -g -Wl,-Ttext -Wl,$(CONFIG_STANDALONE_LOAD_ADDR) \ + -o $@ -Wl,-e -Wl,$(SYM_PREFIX)$(notdir $(<:.o=)) $< $(LIB) \ -L$(gcclibdir) -lgcc
$(SREC): diff --git a/nand_spl/board/amcc/acadia/Makefile b/nand_spl/board/amcc/acadia/Makefile index 84cb8ab..6a75e34 100644 --- a/nand_spl/board/amcc/acadia/Makefile +++ b/nand_spl/board/amcc/acadia/Makefile @@ -27,7 +27,7 @@ include $(TOPDIR)/nand_spl/board/$(BOARDDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/amcc/bamboo/Makefile b/nand_spl/board/amcc/bamboo/Makefile index 6430219..5fa1a3b 100644 --- a/nand_spl/board/amcc/bamboo/Makefile +++ b/nand_spl/board/amcc/bamboo/Makefile @@ -27,7 +27,7 @@ include $(TOPDIR)/nand_spl/board/$(BOARDDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/amcc/canyonlands/Makefile b/nand_spl/board/amcc/canyonlands/Makefile index 509a46e..4e2eae4 100644 --- a/nand_spl/board/amcc/canyonlands/Makefile +++ b/nand_spl/board/amcc/canyonlands/Makefile @@ -27,7 +27,7 @@ include $(TOPDIR)/nand_spl/board/$(BOARDDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/amcc/kilauea/Makefile b/nand_spl/board/amcc/kilauea/Makefile index 104b7e2..55900ed 100644 --- a/nand_spl/board/amcc/kilauea/Makefile +++ b/nand_spl/board/amcc/kilauea/Makefile @@ -27,7 +27,7 @@ include $(TOPDIR)/nand_spl/board/$(BOARDDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/amcc/sequoia/Makefile b/nand_spl/board/amcc/sequoia/Makefile index 54e8a12..dc41c1f 100644 --- a/nand_spl/board/amcc/sequoia/Makefile +++ b/nand_spl/board/amcc/sequoia/Makefile @@ -27,7 +27,7 @@ include $(TOPDIR)/nand_spl/board/$(BOARDDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/mpc8313erdb/Makefile b/nand_spl/board/freescale/mpc8313erdb/Makefile index cff2a43..9fe4472 100644 --- a/nand_spl/board/freescale/mpc8313erdb/Makefile +++ b/nand_spl/board/freescale/mpc8313erdb/Makefile @@ -30,7 +30,7 @@ include $(TOPDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/mpc8315erdb/Makefile b/nand_spl/board/freescale/mpc8315erdb/Makefile index cff2a43..9fe4472 100644 --- a/nand_spl/board/freescale/mpc8315erdb/Makefile +++ b/nand_spl/board/freescale/mpc8315erdb/Makefile @@ -30,7 +30,7 @@ include $(TOPDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/mpc8536ds/Makefile b/nand_spl/board/freescale/mpc8536ds/Makefile index e5388d8..6d91269 100644 --- a/nand_spl/board/freescale/mpc8536ds/Makefile +++ b/nand_spl/board/freescale/mpc8536ds/Makefile @@ -33,7 +33,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/$(CPUDIR)/u-boot-nand_spl.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/mpc8569mds/Makefile b/nand_spl/board/freescale/mpc8569mds/Makefile index e5388d8..6d91269 100644 --- a/nand_spl/board/freescale/mpc8569mds/Makefile +++ b/nand_spl/board/freescale/mpc8569mds/Makefile @@ -33,7 +33,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/$(CPUDIR)/u-boot-nand_spl.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/mpc8572ds/Makefile b/nand_spl/board/freescale/mpc8572ds/Makefile index e5388d8..6d91269 100644 --- a/nand_spl/board/freescale/mpc8572ds/Makefile +++ b/nand_spl/board/freescale/mpc8572ds/Makefile @@ -33,7 +33,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/$(CPUDIR)/u-boot-nand_spl.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/mx31pdk/Makefile b/nand_spl/board/freescale/mx31pdk/Makefile index 43e72c4..1213cf2 100644 --- a/nand_spl/board/freescale/mx31pdk/Makefile +++ b/nand_spl/board/freescale/mx31pdk/Makefile @@ -7,7 +7,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_SPL_BUILD -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_SPL_BUILD -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/p1010rdb/Makefile b/nand_spl/board/freescale/p1010rdb/Makefile index f270faa..8dfaf0c 100644 --- a/nand_spl/board/freescale/p1010rdb/Makefile +++ b/nand_spl/board/freescale/p1010rdb/Makefile @@ -33,7 +33,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/$(CPUDIR)/u-boot-nand_spl.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) $(LDFLAGS) \ $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/p1023rds/Makefile b/nand_spl/board/freescale/p1023rds/Makefile index b288284..39b2588 100644 --- a/nand_spl/board/freescale/p1023rds/Makefile +++ b/nand_spl/board/freescale/p1023rds/Makefile @@ -28,7 +28,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/$(CPUDIR)/u-boot-nand_spl.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/p1_p2_rdb/Makefile b/nand_spl/board/freescale/p1_p2_rdb/Makefile index e5388d8..6d91269 100644 --- a/nand_spl/board/freescale/p1_p2_rdb/Makefile +++ b/nand_spl/board/freescale/p1_p2_rdb/Makefile @@ -33,7 +33,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/$(CPUDIR)/u-boot-nand_spl.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/freescale/p1_p2_rdb_pc/Makefile b/nand_spl/board/freescale/p1_p2_rdb_pc/Makefile index 7146d16..b3514ac 100644 --- a/nand_spl/board/freescale/p1_p2_rdb_pc/Makefile +++ b/nand_spl/board/freescale/p1_p2_rdb_pc/Makefile @@ -33,7 +33,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/$(CPUDIR)/u-boot-nand_spl.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot-nand_spl.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/nand_spl/board/karo/tx25/Makefile b/nand_spl/board/karo/tx25/Makefile index becf7fa..628bfee 100644 --- a/nand_spl/board/karo/tx25/Makefile +++ b/nand_spl/board/karo/tx25/Makefile @@ -28,7 +28,7 @@ nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds LSTSCRIPT= $(nandobj)/board/$(BOARDDIR)/u-boot.lst -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_SPL_BUILD -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_SPL_BUILD -DCONFIG_NAND_SPL diff --git a/nand_spl/board/samsung/smdk6400/Makefile b/nand_spl/board/samsung/smdk6400/Makefile index c9e75ba..75b7b0f 100644 --- a/nand_spl/board/samsung/smdk6400/Makefile +++ b/nand_spl/board/samsung/smdk6400/Makefile @@ -32,7 +32,7 @@ include $(TOPDIR)/nand_spl/board/$(BOARDDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE) $(LDFLAGS) \ $(LDFLAGS_FINAL) -gc-sections AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL -ffunction-sections diff --git a/nand_spl/board/sheldon/simpc8313/Makefile b/nand_spl/board/sheldon/simpc8313/Makefile index 2a3ddac..a73fa87 100644 --- a/nand_spl/board/sheldon/simpc8313/Makefile +++ b/nand_spl/board/sheldon/simpc8313/Makefile @@ -30,7 +30,7 @@ include $(TOPDIR)/config.mk nandobj := $(OBJTREE)/nand_spl/
LDSCRIPT= $(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds -LDFLAGS := -T $(nandobj)u-boot.lds -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ +LDFLAGS := -T $(nandobj)u-boot.lds -Wl,-Ttext $(CONFIG_SYS_TEXT_BASE_SPL) \ $(LDFLAGS) $(LDFLAGS_FINAL) AFLAGS += -DCONFIG_NAND_SPL CFLAGS += -DCONFIG_NAND_SPL diff --git a/spl/Makefile b/spl/Makefile index 3195390..6d9b4ae 100644 --- a/spl/Makefile +++ b/spl/Makefile @@ -139,8 +139,8 @@ $(obj)u-boot-spl.bin: $(obj)u-boot-spl
GEN_UBOOT = \ cd $(obj) && $(LD) $(LDFLAGS) $(LDFLAGS_$(@F)) $(__START) \ - --start-group $(__LIBS) --end-group $(PLATFORM_LIBS) \ - -Map u-boot-spl.map -o u-boot-spl + -Wl,--start-group -Wl,$(__LIBS) -Wl,--end-group -Wl,$(PLATFORM_LIBS) \ + -Wl,-Map=u-boot-spl.map -o u-boot-spl
$(obj)u-boot-spl: depend $(START) $(LIBS) $(obj)u-boot-spl.lds $(GEN_UBOOT)
Dear Marek Vasut,
On 31.10.12 17:32, Marek Vasut wrote:
Flip over from linking with LD to linking with GCC. This has some long-term benefits, like easy path to enabling LTO.
Most of this patch is about passing parameters to the linker invoked by GCC at the linking stage. This involves prefixing most of these with -Wl,<param> . A few more adjustments had to be made though.
The LDFLAGS had to be extended by --build-id=none to prevent generation of the .note.gnu.build-id section, which contains unique build-id we don't care about. Moreover -nostdlib had to be added to LDFLAGS to link properly without pulling in GCC libs during partial link.
The LDFLAGS_FINAL had to be augmented by -Wl,-allow-multiple-definition to prevent GCC from complaining about multiple definitions of the register containing global data.
Signed-off-by: Marek Vasut marex@denx.de Cc: Albert Aribaud albert.u.boot@aribaud.net Cc: Joe Hershberger joe.hershberger@ni.com Cc: Mike Frysinger vapier@gentoo.org Cc: Tom Rini trini@ti.com Cc: Wolfgang Denk wd@denx.de
NOTE: It should mostly work, but _PLEASE_ test it properly. I definitelly can not run it on most of the affected platforms. Besides, it might still hit some build issues, it's not properly compiler-tested. Any additional fixes are welcome ;-)
NOTE: I detected code size being smaller by a few bytes, but then it might cause breakage, so I'd be really cautious here.
<snip>
diff --git a/config.mk b/config.mk index b7cd481..ec8cd6b 100644 --- a/config.mk +++ b/config.mk @@ -137,9 +137,8 @@ binutils-version = $(shell $(SHELL) $(SRCTREE)/tools/binutils-version.sh $(AS)) # AS = $(CROSS_COMPILE)as
-# Always use GNU ld -LD = $(shell if $(CROSS_COMPILE)ld.bfd -v > /dev/null 2>&1; \
then echo "$(CROSS_COMPILE)ld.bfd"; else echo "$(CROSS_COMPILE)ld"; fi;)+# Link with GCC +LD = $(CROSS_COMPILE)gcc
with this change we should also remove LD_VERSION_STRING from $(VERSION_FILE). Currently it will call 'gcc -v' which will print compile switches to stderr.
Compiled and runtime tested on avr32 atngw100mkii, on first sight it seems sane.
Best regards
Andreas Bießmann
Dear Andreas Bießmann,
[...]
-# Always use GNU ld -LD = $(shell if $(CROSS_COMPILE)ld.bfd -v > /dev/null 2>&1; \
then echo "$(CROSS_COMPILE)ld.bfd"; else echo
"$(CROSS_COMPILE)ld";
fi;) +# Link with GCC +LD = $(CROSS_COMPILE)gcc
with this change we should also remove LD_VERSION_STRING from $(VERSION_FILE). Currently it will call 'gcc -v' which will print compile switches to stderr.
Compiled and runtime tested on avr32 atngw100mkii, on first sight it seems sane.
Good catch. I added it to u-boot-testing/dm-gcclink branch already, but will repost after I get a bit more feedback.
Thanks!
Best regards, Marek Vasut
Dear Marek Vasut,
In message 1351701168-7293-1-git-send-email-marex@denx.de you wrote:
Flip over from linking with LD to linking with GCC. This has some long-term benefits, like easy path to enabling LTO.
Could you please explain these supposed benefits in a bit more detail? Please excuse my ignorance, but so far I see just added complexity, but I don't see what it buys us.
Best regards,
Wolfgang Denk
On Wed, Oct 31, 2012 at 11:36:18PM +0100, Wolfgang Denk wrote:
Dear Marek Vasut,
In message 1351701168-7293-1-git-send-email-marex@denx.de you wrote:
Flip over from linking with LD to linking with GCC. This has some long-term benefits, like easy path to enabling LTO.
Could you please explain these supposed benefits in a bit more detail? Please excuse my ignorance, but so far I see just added complexity, but I don't see what it buys us.
Complexity is arguable. Most projects don't call ld directly but let gcc call ld. Doing this brings us in line with what other projects do. As an aside, from my time with CodeSourcery folks directly calling ld was discouraged I swear, but I don't have some reference to back that up. Finally, as Marek said but didn't explain, this brings us a step closer to being able to enable LTO (link time optimization) which may (but we need to experiment) be beneficial in terms of size and performance (since in short gcc re-decides things like positioning, inlining based on the whole program state at link time).
Dear Tom,
In message 20121031224825.GA24095@bill-the-cat you wrote:
Flip over from linking with LD to linking with GCC. This has some long-term benefits, like easy path to enabling LTO.
Could you please explain these supposed benefits in a bit more detail? Please excuse my ignorance, but so far I see just added complexity, but I don't see what it buys us.
Complexity is arguable. Most projects don't call ld directly but let gcc call ld. Doing this brings us in line with what other projects do.
The question is if there are good reasons for these other projects doing it this way - I tend to belive most projects just don't care that much about specific linker options - on the other hand, for bare metal code like U-Boot it is essential to know _exactly_ how the linker is being run. Depending here on the GCC framework which may meddle with options in subtle ways that are not always perfectly understood is something that needs thorough consideration.
As an aside, from my time with CodeSourcery folks directly calling ld was discouraged I swear, but I don't have some reference to back that
I agree with this for "normal programs", i. e. standard conformng code in a standard C environment, where correct use of the appropriate GCC runtime environment and standard libraries is essential. But none of this applies to U-Boot.
up. Finally, as Marek said but didn't explain, this brings us a step closer to being able to enable LTO (link time optimization) which may (but we need to experiment) be beneficial in terms of size and performance (since in short gcc re-decides things like positioning, inlining based on the whole program state at link time).
I do understand this argument. But unless I've seen this working in a real test case I don't feel conficent to acept this. Changing "things like positioning" etc. is something we usually do now want to allow here - instead, we want to have absolute control over such things.
Until I see any such things implemented (and working), this patch falls for me in the group of "unused code" - and given the added complexity (which is definitely non-trivial) it takes me a lot of discipline not to NAK this right away.
Best regards,
Wolfgang Denk
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
On 10/31/12 16:28, Wolfgang Denk wrote:
Dear Tom,
In message 20121031224825.GA24095@bill-the-cat you wrote:
Flip over from linking with LD to linking with GCC. This has some long-term benefits, like easy path to enabling LTO.
Could you please explain these supposed benefits in a bit more detail? Please excuse my ignorance, but so far I see just added complexity, but I don't see what it buys us.
Complexity is arguable. Most projects don't call ld directly but let gcc call ld. Doing this brings us in line with what other projects do.
The question is if there are good reasons for these other projects doing it this way - I tend to belive most projects just don't care that much about specific linker options - on the other hand, for bare metal code like U-Boot it is essential to know _exactly_ how the linker is being run. Depending here on the GCC framework which may meddle with options in subtle ways that are not always perfectly understood is something that needs thorough consideration.
Right. The flip side to this is that the Linux kernel also uses gcc to link, depends on gcc doing what it's told and telling the linker what we want and has a tad more clout than we do when problems arise. If we switch and we find a problem, it's likely the kernel can or does fail as well, which can be useful in getting people to address bugs.
[snip]
up. Finally, as Marek said but didn't explain, this brings us a step closer to being able to enable LTO (link time optimization) which may (but we need to experiment) be beneficial in terms of size and performance (since in short gcc re-decides things like positioning, inlining based on the whole program state at link time).
I do understand this argument. But unless I've seen this working in a real test case I don't feel conficent to acept this. Changing "things like positioning" etc. is something we usually do now want to allow here - instead, we want to have absolute control over such things.
Until I see any such things implemented (and working), this patch falls for me in the group of "unused code" - and given the added complexity (which is definitely non-trivial) it takes me a lot of discipline not to NAK this right away.
I appreciate your restraint here. And, I agree that we don't need to bring this in until we've investigated LTO and found it brings benefits to the project. It could indeed mess up and not obey the times we've re-ordered code segments out of necessity rather than space optimization. But it might also let us stop playing those games and get better results with all of the text together.
- -- Tom
Dear Wolfgang Denk,
Dear Marek Vasut,
In message 1351701168-7293-1-git-send-email-marex@denx.de you wrote:
Flip over from linking with LD to linking with GCC. This has some long-term benefits, like easy path to enabling LTO.
Could you please explain these supposed benefits in a bit more detail?
Yes, thanks for the review (I really needed one from you on this)!
So, here comes the list: 1) It's cool to link with gcc, duh ;-) 2) You can enable LTO eventually -- long term plan -- which proved can shrink the code size a bit 3) Usage of LLVM/CLANG is now much more straightforward 4) Binutils usually lag behind the GCC development a bit, by using GCC to do the link, we can remedy this problem
But actually, the 2) is the most important part. LTO will hopefully help us optimize U-Boot for size even better than it is now. But that will still need much more research. So this is only a patch that shall prepare the groundwork for this further research.
Please excuse my ignorance, but so far I see just added complexity, but I don't see what it buys us.
Best regards,
Wolfgang Denk
Best regards, Marek Vasut
Dear Marek,
In message 201210312351.35977.marex@denx.de you wrote:
Could you please explain these supposed benefits in a bit more detail?
Yes, thanks for the review (I really needed one from you on this)!
So, here comes the list:
- It's cool to link with gcc, duh ;-)
Is it - and why exactly?
- You can enable LTO eventually -- long term plan -- which proved can shrink
the code size a bit
Do you have a workign example? You know, we don;t like adding dead code...
- Usage of LLVM/CLANG is now much more straightforward
Please elucidate?
- Binutils usually lag behind the GCC development a bit, by using GCC to do the
link, we can remedy this problem
Grrrrghhhg. I lost you here. By not calling ld directly (where we know exactly what we are doing), but through a (somewhat unknown) GCC framework, we can magicly adjust any (claimed - by you) version differences? I cannot parse this.
But actually, the 2) is the most important part. LTO will hopefully help us optimize U-Boot for size even better than it is now. But that will still need much more research. So this is only a patch that shall prepare the groundwork for this further research.
As is, it's just unused or dead code that adds a lot of complexity and buys nothing. Please submit as part of a patch series that makes successfull (and tested) use of LTO.
Best regards,
Wolfgang Denk
Dear Wolfgang Denk,
Dear Marek,
In message 201210312351.35977.marex@denx.de you wrote:
Could you please explain these supposed benefits in a bit more detail?
Yes, thanks for the review (I really needed one from you on this)!
So, here comes the list:
- It's cool to link with gcc, duh ;-)
Is it - and why exactly?
It's all the rage now (better ignore this point) ;-)
- You can enable LTO eventually -- long term plan -- which proved can
shrink the code size a bit
Do you have a workign example? You know, we don;t like adding dead code...
We've been digging with Albert, but nothing we can release just yet. This is a groundwork patch.
- Usage of LLVM/CLANG is now much more straightforward
Please elucidate?
Now you can simply replace gcc with clang and that _should_ work. Sure, I expect more work will be needed here, but this patch gives you all the ground to do that.
- Binutils usually lag behind the GCC development a bit, by using GCC to
do the link, we can remedy this problem
Grrrrghhhg. I lost you here. By not calling ld directly (where we know exactly what we are doing), but through a (somewhat unknown) GCC framework, we can magicly adjust any (claimed - by you) version differences? I cannot parse this.
GCC can do all the optimization magic (LTO ...) and then just let linker do the linking.
But actually, the 2) is the most important part. LTO will hopefully help us optimize U-Boot for size even better than it is now. But that will still need much more research. So this is only a patch that shall prepare the groundwork for this further research.
As is, it's just unused or dead code that adds a lot of complexity and buys nothing. Please submit as part of a patch series that makes successfull (and tested) use of LTO.
No, I won't, I don't have that part ready yet.
Besides, the sandbox target already uses gcc linking. Shall we also convert it to use LD instead then ?
Best regards, Marek Vasut
Dear Marek,
In message 201211010045.40817.marex@denx.de you wrote:
- You can enable LTO eventually -- long term plan -- which proved can
shrink the code size a bit
Do you have a workign example? You know, we don;t like adding dead code...
We've been digging with Albert, but nothing we can release just yet. This is a groundwork patch.
Dead code, which will not be added, then.
- Usage of LLVM/CLANG is now much more straightforward
Please elucidate?
Now you can simply replace gcc with clang and that _should_ work. Sure, I expect more work will be needed here, but this patch gives you all the ground to do that.
I. e. it's all speculation only? Such doesn't by much...
- Binutils usually lag behind the GCC development a bit, by using GCC to
do the link, we can remedy this problem
Grrrrghhhg. I lost you here. By not calling ld directly (where we know exactly what we are doing), but through a (somewhat unknown) GCC framework, we can magicly adjust any (claimed - by you) version differences? I cannot parse this.
GCC can do all the optimization magic (LTO ...) and then just let linker do the linking.
You were talking about "Binutils usually lag behind the GCC development". Now I would like you to explain how "by using GCC to do the link, we can remedy this problem".
You fail to provide any such explanation.
But actually, the 2) is the most important part. LTO will hopefully help us optimize U-Boot for size even better than it is now. But that will still need much more research. So this is only a patch that shall prepare the groundwork for this further research.
As is, it's just unused or dead code that adds a lot of complexity and buys nothing. Please submit as part of a patch series that makes successfull (and tested) use of LTO.
No, I won't, I don't have that part ready yet.
Then please _re_submit when you have the rest that actually needs any such changes.
Besides, the sandbox target already uses gcc linking. Shall we also convert it to use LD instead then ?
Note that sandbox is actually very different, in such as it really tried to implement a standard onforming C program, running in a standard C execution environment. This is totally different from the bare metal code we have on any real hardware.
Best regards,
Wolfgang Denk
Dear Wolfgang Denk,
Dear Marek,
In message 201211010045.40817.marex@denx.de you wrote:
- You can enable LTO eventually -- long term plan -- which proved
can shrink the code size a bit
Do you have a workign example? You know, we don;t like adding dead code...
We've been digging with Albert, but nothing we can release just yet. This is a groundwork patch.
Dead code, which will not be added, then.
[...]
Ok, let's end the discussion here then. Patch is NAK'ed and I'll resubmit it when I have something with LTO.
Best regards, Marek Vasut
participants (4)
-
Andreas Bießmann -
Marek Vasut -
Tom Rini -
Wolfgang Denk