arm: Have the linker garbage-collect unused functions and variables
This patch activates -ffunction-sections and -fdata-sections for the compiler and --gc-sections for the linker. This will strip out all unused functions and static/global variables from the final binaries and reduce the amount of data we need to read over SPI. A quick test with ToT images shows a 2.5k (13%) / 10k (29%) / 12k (28%) reduction on Nyan and 3k (38%) / 23k (50%) / 13k (29%) on Pit, respectively for bootblock / romstage / ramstage. Change-Id: I052411d4ad190d0395921ac4d4677341fb91568a Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/177111 (cherry picked from commit 5635b138778dea67a5f179e13003132be07f7e59) Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com> Reviewed-on: http://review.coreboot.org/6904 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
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@ -62,9 +62,9 @@ bootblock-y += memmove.S
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$(objcbfs)/bootblock.debug: $(src)/arch/arm/bootblock.ld $(obj)/ldoptions $$(bootblock-objs)
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@printf " LINK $(subst $(obj)/,,$(@))\n"
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ifeq ($(CONFIG_COMPILER_LLVM_CLANG),y)
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$(LD_bootblock) -m armelf_linux_eabi -static -o $@ -L$(obj) $< -T $(src)/arch/arm/bootblock.ld
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$(LD_bootblock) -m armelf_linux_eabi --gc-sections -static -o $@ -L$(obj) $< -T $(src)/arch/arm/bootblock.ld
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else
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$(CC_bootblock) $(CFLAGS_bootblock) -nostartfiles -static -o $@ -L$(obj) -T $(src)/arch/arm/bootblock.ld -Wl,--start-group $(bootblock-objs) $(LIBGCC_FILE_NAME_bootblock) -Wl,--end-group
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$(CC_bootblock) $(CFLAGS_bootblock) -nostartfiles -Wl,--gc-sections -static -o $@ -L$(obj) -T $(src)/arch/arm/bootblock.ld -Wl,--start-group $(bootblock-objs) $(LIBGCC_FILE_NAME_bootblock) -Wl,--end-group
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endif
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endif # CONFIG_ARCH_BOOTBLOCK_ARM
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@ -87,9 +87,9 @@ VBOOT_STUB_DEPS += $(obj)/arch/arm/eabi_compat.rmodules_arm.o
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$(objcbfs)/romstage.debug: $$(romstage-objs) $(src)/arch/arm/romstage.ld $(obj)/ldoptions
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@printf " LINK $(subst $(obj)/,,$(@))\n"
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ifeq ($(CONFIG_COMPILER_LLVM_CLANG),y)
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$(LD_romstage) -nostdlib -nostartfiles -static -o $@ -L$(obj) $(romstage-objs) -T $(src)/arch/arm/romstage.ld
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$(LD_romstage) -nostdlib -nostartfiles --gc-sections -static -o $@ -L$(obj) $(romstage-objs) -T $(src)/arch/arm/romstage.ld
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else
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$(CC_romstage) $(CFLAGS_romstage) -nostartfiles -static -o $@ -L$(obj) -T $(src)/arch/arm/romstage.ld -Wl,--start-group $(romstage-objs) $(LIBGCC_FILE_NAME_romstage) -Wl,--end-group
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$(CC_romstage) $(CFLAGS_romstage) -nostartfiles -Wl,--gc-sections -static -o $@ -L$(obj) -T $(src)/arch/arm/romstage.ld -Wl,--start-group $(romstage-objs) $(LIBGCC_FILE_NAME_romstage) -Wl,--end-group
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endif
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endif # CONFIG_ARCH_ROMSTAGE_ARM
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@ -122,9 +122,9 @@ endif
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$(objgenerated)/ramstage.o: $(stages_o) $$(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage)
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@printf " CC $(subst $(obj)/,,$(@))\n"
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ifeq ($(CONFIG_COMPILER_LLVM_CLANG),y)
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$(LD_ramstage) -m -m armelf_linux_eabi -r -o $@ --wrap __divdi3 --wrap __udivdi3 --wrap __moddi3 --wrap __umoddi3 --wrap __uidiv --start-group $(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage) --end-group
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$(LD_ramstage) -m -m armelf_linux_eabi --gc-sections -r -o $@ --wrap __divdi3 --wrap __udivdi3 --wrap __moddi3 --wrap __umoddi3 --wrap __uidiv --start-group $(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage) --end-group
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else
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$(CC_ramstage) $(CFLAGS_ramstage) $(CPPFLAGS_ramstage) -nostdlib -r -o $@ -Wl,--start-group $(stages_o) $(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage) -Wl,--end-group
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$(CC_ramstage) $(CFLAGS_ramstage) $(CPPFLAGS_ramstage) -nostdlib -Wl,--gc-sections -r -o $@ -Wl,--start-group $(stages_o) $(ramstage-objs) $(LIBGCC_FILE_NAME_ramstage) -Wl,--end-group
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endif
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endif # CONFIG_ARCH_RAMSTAGE_ARM
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@ -28,23 +28,25 @@ PHDRS
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to_load PT_LOAD;
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}
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ENTRY(_start)
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TARGET(binary)
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SECTIONS
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{
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ROMLOC = CONFIG_BOOTBLOCK_BASE;
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. = CONFIG_BOOTBLOCK_BASE;
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/* This section might be better named .setup */
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.rom ROMLOC : {
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_rom = .;
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.bootblock . : {
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*(.start);
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*(.id);
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KEEP(*(.id));
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*(.text);
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*(.text.*);
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*(.rom.text);
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*(.rom.data);
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*(.rom.data.*);
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*(.rodata);
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*(.rodata.*);
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_erom = .;
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*(.data);
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*(.data.*);
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*(.bss);
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*(.bss.*);
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*(.sbss);
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*(.sbss.*);
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} : to_load = 0xff
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/DISCARD/ : {
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@ -48,7 +48,7 @@ SECTIONS
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.ctors : {
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. = ALIGN(0x100);
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__CTOR_LIST__ = .;
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*(.ctors);
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KEEP(*(.ctors));
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LONG(0);
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__CTOR_END__ = .;
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}
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@ -57,13 +57,13 @@ SECTIONS
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_rodata = .;
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. = ALIGN(4);
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pci_drivers = . ;
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*(.rodata.pci_driver)
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KEEP(*(.rodata.pci_driver));
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epci_drivers = . ;
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cpu_drivers = . ;
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*(.rodata.cpu_driver)
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KEEP(*(.rodata.cpu_driver));
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ecpu_drivers = . ;
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_bs_init_begin = .;
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*(.bs_init)
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KEEP(*(.bs_init));
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_bs_init_end = .;
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*(.rodata)
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*(.rodata.*)
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@ -83,6 +83,7 @@ SECTIONS
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.data : {
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_data = .;
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*(.data)
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*(.data.*)
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_edata = .;
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}
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@ -90,26 +91,27 @@ SECTIONS
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* initialized on startup. (typically uninitialized global variables)
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* crt0.S fills between _bss and _ebss with zeroes.
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*/
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_bss = .;
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.bss . : {
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_bss = .;
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*(.bss)
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*(.bss.*)
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*(.sbss)
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*(COMMON)
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*(.sbss.*)
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_ebss = .;
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}
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_ebss = .;
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_end = .;
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/* coreboot really "ends" here. Only heap and stack are placed after
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* this line.
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*/
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_heap = .;
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.heap . : {
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_heap = .;
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/* Reserve CONFIG_HEAP_SIZE bytes for the heap */
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. = CONFIG_HEAP_SIZE ;
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. = ALIGN(4);
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_eheap = .;
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}
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_eheap = .;
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/* The ram segment. This includes all memory used by the memory
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* resident copy of coreboot, except the tables that are produced on
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@ -38,19 +38,19 @@ SECTIONS
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. = CONFIG_ROMSTAGE_BASE;
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.romtext . : {
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_rom = .;
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_start = .;
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*(.text.stage_entry.arm);
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*(.text.startup);
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*(.text);
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*(.text.*);
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} : to_load
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.romdata . : {
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*(.rodata);
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*(.machine_param);
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*(.rodata.*);
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*(.data);
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*(.data.*);
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. = ALIGN(8);
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_erom = .;
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}
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/* bss does not contain data, it is just a space that should be zero
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@ -61,12 +61,12 @@ SECTIONS
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. = ALIGN(8);
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_bss = .;
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*(.bss)
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*(.bss.*)
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*(.sbss)
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*(COMMON)
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*(.sbss.*)
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_ebss = .;
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}
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_ebss = .;
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_end = .;
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/* Discard the sections we don't need/want */
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@ -57,10 +57,7 @@ ARCHDIR-i386 := x86
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ARCHDIR-x86_32 := x86
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ARCHDIR-arm := arm
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CFLAGS_arm += \
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-mno-unaligned-access\
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-mthumb\
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-mthumb-interwork
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CFLAGS_arm := -mno-unaligned-access -ffunction-sections -fdata-sections
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toolchain_to_dir = \
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$(foreach arch,$(ARCH_SUPPORTED),\
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