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- From e3d8676f5722b7622685581e06e8f53e6138e3ab Mon Sep 17 00:00:00 2001
- From: Felix Fietkau <[email protected]>
- Date: Sat, 15 Jul 2017 23:42:36 +0200
- Subject: use -ffunction-sections, -fdata-sections and --gc-sections
- In combination with kernel symbol export stripping this significantly reduces
- the kernel image size. Used on both ARM and MIPS architectures.
- Signed-off-by: Felix Fietkau <[email protected]>
- Signed-off-by: Jonas Gorski <[email protected]>
- Signed-off-by: Gabor Juhos <[email protected]>
- ---
- Makefile | 10 +++----
- arch/arm/Kconfig | 1 +
- arch/arm/boot/compressed/Makefile | 1 +
- arch/arm/kernel/vmlinux.lds.S | 26 ++++++++--------
- arch/mips/Kconfig | 1 +
- arch/mips/kernel/vmlinux.lds.S | 4 +--
- include/asm-generic/vmlinux.lds.h | 63 ++++++++++++++++++++-------------------
- 7 files changed, 55 insertions(+), 51 deletions(-)
- --- a/arch/arm/Kconfig
- +++ b/arch/arm/Kconfig
- @@ -111,6 +111,7 @@ config ARM
- select HAVE_UID16
- select HAVE_VIRT_CPU_ACCOUNTING_GEN
- select IRQ_FORCED_THREADING
- + select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
- select MODULES_USE_ELF_REL
- select NEED_DMA_MAP_STATE
- select OF_EARLY_FLATTREE if OF
- --- a/arch/arm/boot/compressed/Makefile
- +++ b/arch/arm/boot/compressed/Makefile
- @@ -106,6 +106,7 @@ ifeq ($(CONFIG_FUNCTION_TRACER),y)
- ORIG_CFLAGS := $(KBUILD_CFLAGS)
- KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
- endif
- +KBUILD_CFLAGS_KERNEL := $(patsubst -f%-sections,,$(KBUILD_CFLAGS_KERNEL))
-
- # -fstack-protector-strong triggers protection checks in this code,
- # but it is being used too early to link to meaningful stack_chk logic.
- --- a/arch/arm/kernel/vmlinux.lds.S
- +++ b/arch/arm/kernel/vmlinux.lds.S
- @@ -100,24 +100,24 @@ SECTIONS
- }
- .init.arch.info : {
- __arch_info_begin = .;
- - *(.arch.info.init)
- + KEEP(*(.arch.info.init))
- __arch_info_end = .;
- }
- .init.tagtable : {
- __tagtable_begin = .;
- - *(.taglist.init)
- + KEEP(*(.taglist.init))
- __tagtable_end = .;
- }
- #ifdef CONFIG_SMP_ON_UP
- .init.smpalt : {
- __smpalt_begin = .;
- - *(.alt.smp.init)
- + KEEP(*(.alt.smp.init))
- __smpalt_end = .;
- }
- #endif
- .init.pv_table : {
- __pv_table_begin = .;
- - *(.pv_table)
- + KEEP(*(.pv_table))
- __pv_table_end = .;
- }
-
- --- a/arch/arm/kernel/vmlinux.lds.h
- +++ b/arch/arm/kernel/vmlinux.lds.h
- @@ -22,13 +22,13 @@
- #define ARM_MMU_DISCARD(x)
- #else
- #define ARM_MMU_KEEP(x)
- -#define ARM_MMU_DISCARD(x) x
- +#define ARM_MMU_DISCARD(x) KEEP(x)
- #endif
-
- #define PROC_INFO \
- . = ALIGN(4); \
- __proc_info_begin = .; \
- - *(.proc.info.init) \
- + KEEP(*(.proc.info.init)) \
- __proc_info_end = .;
-
- #define HYPERVISOR_TEXT \
- @@ -39,11 +39,11 @@
- #define IDMAP_TEXT \
- ALIGN_FUNCTION(); \
- __idmap_text_start = .; \
- - *(.idmap.text) \
- + KEEP(*(.idmap.text)) \
- __idmap_text_end = .; \
- . = ALIGN(PAGE_SIZE); \
- __hyp_idmap_text_start = .; \
- - *(.hyp.idmap.text) \
- + KEEP(*(.hyp.idmap.text)) \
- __hyp_idmap_text_end = .;
-
- #define ARM_DISCARD \
- @@ -86,12 +86,12 @@
- . = ALIGN(8); \
- .ARM.unwind_idx : { \
- __start_unwind_idx = .; \
- - *(.ARM.exidx*) \
- + KEEP(*(.ARM.exidx*)) \
- __stop_unwind_idx = .; \
- } \
- .ARM.unwind_tab : { \
- __start_unwind_tab = .; \
- - *(.ARM.extab*) \
- + KEEP(*(.ARM.extab*)) \
- __stop_unwind_tab = .; \
- }
-
- @@ -102,14 +102,14 @@
- #define ARM_VECTORS \
- __vectors_start = .; \
- .vectors 0xffff0000 : AT(__vectors_start) { \
- - *(.vectors) \
- + KEEP(*(.vectors)) \
- } \
- . = __vectors_start + SIZEOF(.vectors); \
- __vectors_end = .; \
- \
- __stubs_start = .; \
- .stubs ADDR(.vectors) + 0x1000 : AT(__stubs_start) { \
- - *(.stubs) \
- + KEEP(*(.stubs)) \
- } \
- . = __stubs_start + SIZEOF(.stubs); \
- __stubs_end = .; \
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