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	Refreshed all patches. Compile-tested on: cns3xxx Runtime-tested on: cns3xxx Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
		
			
				
	
	
		
			193 lines
		
	
	
		
			5.6 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
			
		
		
	
	
			193 lines
		
	
	
		
			5.6 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
From e3d8676f5722b7622685581e06e8f53e6138e3ab Mon Sep 17 00:00:00 2001
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From: Felix Fietkau <nbd@nbd.name>
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Date: Sat, 15 Jul 2017 23:42:36 +0200
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Subject: use -ffunction-sections, -fdata-sections and --gc-sections
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In combination with kernel symbol export stripping this significantly reduces
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the kernel image size. Used on both ARM and MIPS architectures.
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Signed-off-by: Felix Fietkau <nbd@nbd.name>
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Signed-off-by: Jonas Gorski <jogo@openwrt.org>
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Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
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---
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 Makefile                          | 10 +++----
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 arch/arm/Kconfig                  |  1 +
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 arch/arm/boot/compressed/Makefile |  1 +
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 arch/arm/kernel/vmlinux.lds.S     | 26 ++++++++--------
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 arch/mips/Kconfig                 |  1 +
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 arch/mips/kernel/vmlinux.lds.S    |  4 +--
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 include/asm-generic/vmlinux.lds.h | 63 ++++++++++++++++++++-------------------
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 7 files changed, 55 insertions(+), 51 deletions(-)
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--- a/Makefile
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+++ b/Makefile
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@@ -294,6 +294,11 @@ else
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 scripts/Kbuild.include: ;
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 include scripts/Kbuild.include
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+ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
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+KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
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+LDFLAGS_vmlinux += --gc-sections
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+endif
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+
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 # Read KERNELRELEASE from include/config/kernel.release (if it exists)
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 KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
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 KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
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@@ -782,11 +787,6 @@ ifdef CONFIG_DEBUG_SECTION_MISMATCH
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 KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
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 endif
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-ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
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-KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
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-LDFLAGS_vmlinux += --gc-sections
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-endif
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-
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 # arch Makefile may override CC so keep this after arch Makefile is included
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 NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
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--- a/arch/arm/Kconfig
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+++ b/arch/arm/Kconfig
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@@ -98,6 +98,7 @@ config ARM
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 	select HAVE_UID16
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 	select HAVE_VIRT_CPU_ACCOUNTING_GEN
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 	select IRQ_FORCED_THREADING
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+	select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
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 	select MODULES_USE_ELF_REL
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 	select NEED_DMA_MAP_STATE
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 	select NO_BOOTMEM
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--- a/arch/arm/boot/compressed/Makefile
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+++ b/arch/arm/boot/compressed/Makefile
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@@ -106,6 +106,7 @@ ifeq ($(CONFIG_FUNCTION_TRACER),y)
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 ORIG_CFLAGS := $(KBUILD_CFLAGS)
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 KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
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 endif
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+KBUILD_CFLAGS_KERNEL := $(patsubst -f%-sections,,$(KBUILD_CFLAGS_KERNEL))
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 # -fstack-protector-strong triggers protection checks in this code,
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 # but it is being used too early to link to meaningful stack_chk logic.
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--- a/arch/arm/kernel/vmlinux.lds.S
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+++ b/arch/arm/kernel/vmlinux.lds.S
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@@ -100,24 +100,24 @@ SECTIONS
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 	}
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 	.init.arch.info : {
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 		__arch_info_begin = .;
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-		*(.arch.info.init)
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+		KEEP(*(.arch.info.init))
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 		__arch_info_end = .;
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 	}
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 	.init.tagtable : {
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 		__tagtable_begin = .;
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-		*(.taglist.init)
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+		KEEP(*(.taglist.init))
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 		__tagtable_end = .;
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 	}
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 #ifdef CONFIG_SMP_ON_UP
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 	.init.smpalt : {
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 		__smpalt_begin = .;
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-		*(.alt.smp.init)
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+		KEEP(*(.alt.smp.init))
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 		__smpalt_end = .;
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 	}
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 #endif
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 	.init.pv_table : {
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 		__pv_table_begin = .;
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-		*(.pv_table)
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+		KEEP(*(.pv_table))
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 		__pv_table_end = .;
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 	}
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--- a/arch/arm/kernel/vmlinux.lds.h
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+++ b/arch/arm/kernel/vmlinux.lds.h
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@@ -22,13 +22,13 @@
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 #define ARM_MMU_DISCARD(x)
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 #else
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 #define ARM_MMU_KEEP(x)
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-#define ARM_MMU_DISCARD(x)	x
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+#define ARM_MMU_DISCARD(x)	KEEP(x)
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 #endif
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 #define PROC_INFO							\
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 		. = ALIGN(4);						\
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 		__proc_info_begin = .;					\
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-		*(.proc.info.init)					\
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+		KEEP(*(.proc.info.init))				\
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 		__proc_info_end = .;
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 #define HYPERVISOR_TEXT							\
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@@ -39,11 +39,11 @@
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 #define IDMAP_TEXT							\
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 		ALIGN_FUNCTION();					\
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 		__idmap_text_start = .;					\
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-		*(.idmap.text)						\
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+		KEEP(*(.idmap.text))					\
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 		__idmap_text_end = .;					\
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 		. = ALIGN(PAGE_SIZE);					\
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 		__hyp_idmap_text_start = .;				\
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-		*(.hyp.idmap.text)					\
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+		KEEP(*(.hyp.idmap.text))				\
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 		__hyp_idmap_text_end = .;
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 #define ARM_DISCARD							\
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@@ -86,12 +86,12 @@
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 	. = ALIGN(8);							\
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 	.ARM.unwind_idx : {						\
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 		__start_unwind_idx = .;					\
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-		*(.ARM.exidx*)						\
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+		KEEP(*(.ARM.exidx*))					\
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 		__stop_unwind_idx = .;					\
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 	}								\
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 	.ARM.unwind_tab : {						\
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 		__start_unwind_tab = .;					\
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-		*(.ARM.extab*)						\
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+		KEEP(*(.ARM.extab*))					\
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 		__stop_unwind_tab = .;					\
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 	}
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@@ -102,14 +102,14 @@
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 #define ARM_VECTORS							\
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 	__vectors_start = .;						\
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 	.vectors 0xffff0000 : AT(__vectors_start) {			\
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-		*(.vectors)						\
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+		KEEP(*(.vectors))					\
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 	}								\
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 	. = __vectors_start + SIZEOF(.vectors);				\
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 	__vectors_end = .;						\
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 									\
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 	__stubs_start = .;						\
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 	.stubs ADDR(.vectors) + 0x1000 : AT(__stubs_start) {		\
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-		*(.stubs)						\
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+		KEEP(*(.stubs))						\
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 	}								\
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 	. = __stubs_start + SIZEOF(.stubs);				\
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 	__stubs_end = .;						\
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--- a/arch/mips/Kconfig
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+++ b/arch/mips/Kconfig
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@@ -43,6 +43,7 @@ config MIPS
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 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES && 64BIT
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 	select HAVE_CBPF_JIT if (!64BIT && !CPU_MICROMIPS)
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 	select HAVE_EBPF_JIT if (64BIT && !CPU_MICROMIPS)
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+	select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
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 	select HAVE_CONTEXT_TRACKING
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 	select HAVE_COPY_THREAD_TLS
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 	select HAVE_C_RECORDMCOUNT
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--- a/arch/mips/kernel/vmlinux.lds.S
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+++ b/arch/mips/kernel/vmlinux.lds.S
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@@ -72,7 +72,7 @@ SECTIONS
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 	/* Exception table for data bus errors */
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 	__dbe_table : {
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 		__start___dbe_table = .;
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-		*(__dbe_table)
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+		KEEP(*(__dbe_table))
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 		__stop___dbe_table = .;
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 	}
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@@ -123,7 +123,7 @@ SECTIONS
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 	. = ALIGN(4);
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 	.mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) {
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 		__mips_machines_start = .;
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-		*(.mips.machines.init)
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+		KEEP(*(.mips.machines.init))
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 		__mips_machines_end = .;
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 	}
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