kernel: use -ffunction-sections, -fdata-sections and --gc-sections on mips

in combination with kernel symbol export stripping this significantly reduces
the kernel image size

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35320 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 372 insertions, 0 deletions

diff --git a/target/linux/generic/patches-3.7/220-gc_sections.patch b/target/linux/generic/patches-3.7/220-gc_sections.patch
new file mode 100644
index 0000000000..8a52a1eec8
--- /dev/null
+++ b/target/linux/generic/patches-3.7/220-gc_sections.patch
@@ -0,0 +1,372 @@
+--- a/arch/mips/Makefile
++++ b/arch/mips/Makefile
+@@ -89,10 +89,12 @@ all-$(CONFIG_SYS_SUPPORTS_ZBOOT)+= vmlin
+ #
+ cflags-y			+= -G 0 -mno-abicalls -fno-pic -pipe
+ cflags-y			+= -msoft-float
+-LDFLAGS_vmlinux			+= -G 0 -static -n -nostdlib
++LDFLAGS_vmlinux			+= -G 0 -static -n -nostdlib --gc-sections
+ KBUILD_AFLAGS_MODULE		+= -mlong-calls
+ KBUILD_CFLAGS_MODULE		+= -mlong-calls
+ 
++KBUILD_CFLAGS_KERNEL		+= -ffunction-sections -fdata-sections
++
+ cflags-y += -ffreestanding
+ 
+ #
+--- a/arch/mips/kernel/vmlinux.lds.S
++++ b/arch/mips/kernel/vmlinux.lds.S
+@@ -66,7 +66,7 @@ SECTIONS
+ 	/* Exception table for data bus errors */
+ 	__dbe_table : {
+ 		__start___dbe_table = .;
+-		*(__dbe_table)
++		KEEP(*(__dbe_table))
+ 		__stop___dbe_table = .;
+ 	}
+ 
+@@ -111,7 +111,7 @@ SECTIONS
+ 	. = ALIGN(4);
+ 	.mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) {
+ 		__mips_machines_start = .;
+-		*(.mips.machines.init)
++		KEEP(*(.mips.machines.init))
+ 		__mips_machines_end = .;
+ 	}
+ 
+--- a/include/asm-generic/vmlinux.lds.h
++++ b/include/asm-generic/vmlinux.lds.h
+@@ -101,7 +101,7 @@
+ #ifdef CONFIG_FTRACE_MCOUNT_RECORD
+ #define MCOUNT_REC()	. = ALIGN(8);				\
+ 			VMLINUX_SYMBOL(__start_mcount_loc) = .; \
+-			*(__mcount_loc)				\
++			KEEP(*(__mcount_loc))			\
+ 			VMLINUX_SYMBOL(__stop_mcount_loc) = .;
+ #else
+ #define MCOUNT_REC()
+@@ -109,7 +109,7 @@
+ 
+ #ifdef CONFIG_TRACE_BRANCH_PROFILING
+ #define LIKELY_PROFILE()	VMLINUX_SYMBOL(__start_annotated_branch_profile) = .; \
+-				*(_ftrace_annotated_branch)			      \
++				KEEP(*(_ftrace_annotated_branch))		      \
+ 				VMLINUX_SYMBOL(__stop_annotated_branch_profile) = .;
+ #else
+ #define LIKELY_PROFILE()
+@@ -117,7 +117,7 @@
+ 
+ #ifdef CONFIG_PROFILE_ALL_BRANCHES
+ #define BRANCH_PROFILE()	VMLINUX_SYMBOL(__start_branch_profile) = .;   \
+-				*(_ftrace_branch)			      \
++				KEEP(*(_ftrace_branch))			      \
+ 				VMLINUX_SYMBOL(__stop_branch_profile) = .;
+ #else
+ #define BRANCH_PROFILE()
+@@ -126,7 +126,7 @@
+ #ifdef CONFIG_EVENT_TRACING
+ #define FTRACE_EVENTS()	. = ALIGN(8);					\
+ 			VMLINUX_SYMBOL(__start_ftrace_events) = .;	\
+-			*(_ftrace_events)				\
++			KEEP(*(_ftrace_events))				\
+ 			VMLINUX_SYMBOL(__stop_ftrace_events) = .;
+ #else
+ #define FTRACE_EVENTS()
+@@ -134,7 +134,7 @@
+ 
+ #ifdef CONFIG_TRACING
+ #define TRACE_PRINTKS() VMLINUX_SYMBOL(__start___trace_bprintk_fmt) = .;      \
+-			 *(__trace_printk_fmt) /* Trace_printk fmt' pointer */ \
++			 KEEP(*(__trace_printk_fmt)) /* Trace_printk fmt' pointer */ \
+ 			 VMLINUX_SYMBOL(__stop___trace_bprintk_fmt) = .;
+ #else
+ #define TRACE_PRINTKS()
+@@ -143,7 +143,7 @@
+ #ifdef CONFIG_FTRACE_SYSCALLS
+ #define TRACE_SYSCALLS() . = ALIGN(8);					\
+ 			 VMLINUX_SYMBOL(__start_syscalls_metadata) = .;	\
+-			 *(__syscalls_metadata)				\
++			 KEEP(*(__syscalls_metadata))			\
+ 			 VMLINUX_SYMBOL(__stop_syscalls_metadata) = .;
+ #else
+ #define TRACE_SYSCALLS()
+@@ -153,7 +153,7 @@
+ #define KERNEL_DTB()							\
+ 	STRUCT_ALIGN();							\
+ 	VMLINUX_SYMBOL(__dtb_start) = .;				\
+-	*(.dtb.init.rodata)						\
++	KEEP(*(.dtb.init.rodata))					\
+ 	VMLINUX_SYMBOL(__dtb_end) = .;
+ 
+ /* .data section */
+@@ -173,15 +173,16 @@
+ 	/* implement dynamic printk debug */				\
+ 	. = ALIGN(8);                                                   \
+ 	VMLINUX_SYMBOL(__start___jump_table) = .;                       \
+-	*(__jump_table)                                                 \
++	KEEP(*(__jump_table))                                           \
+ 	VMLINUX_SYMBOL(__stop___jump_table) = .;                        \
+ 	. = ALIGN(8);							\
+ 	VMLINUX_SYMBOL(__start___verbose) = .;                          \
+-	*(__verbose)                                                    \
++	KEEP(*(__verbose))                                              \
+ 	VMLINUX_SYMBOL(__stop___verbose) = .;				\
+ 	LIKELY_PROFILE()		       				\
+ 	BRANCH_PROFILE()						\
+-	TRACE_PRINTKS()
++	TRACE_PRINTKS()							\
++	*(.data.*)
+ 
+ /*
+  * Data section helpers
+@@ -235,39 +236,39 @@
+ 	/* PCI quirks */						\
+ 	.pci_fixup        : AT(ADDR(.pci_fixup) - LOAD_OFFSET) {	\
+ 		VMLINUX_SYMBOL(__start_pci_fixups_early) = .;		\
+-		*(.pci_fixup_early)					\
++		KEEP(*(.pci_fixup_early))				\
+ 		VMLINUX_SYMBOL(__end_pci_fixups_early) = .;		\
+ 		VMLINUX_SYMBOL(__start_pci_fixups_header) = .;		\
+-		*(.pci_fixup_header)					\
++		KEEP(*(.pci_fixup_header))				\
+ 		VMLINUX_SYMBOL(__end_pci_fixups_header) = .;		\
+ 		VMLINUX_SYMBOL(__start_pci_fixups_final) = .;		\
+-		*(.pci_fixup_final)					\
++		KEEP(*(.pci_fixup_final))				\
+ 		VMLINUX_SYMBOL(__end_pci_fixups_final) = .;		\
+ 		VMLINUX_SYMBOL(__start_pci_fixups_enable) = .;		\
+-		*(.pci_fixup_enable)					\
++		KEEP(*(.pci_fixup_enable))				\
+ 		VMLINUX_SYMBOL(__end_pci_fixups_enable) = .;		\
+ 		VMLINUX_SYMBOL(__start_pci_fixups_resume) = .;		\
+-		*(.pci_fixup_resume)					\
++		KEEP(*(.pci_fixup_resume))				\
+ 		VMLINUX_SYMBOL(__end_pci_fixups_resume) = .;		\
+ 		VMLINUX_SYMBOL(__start_pci_fixups_resume_early) = .;	\
+-		*(.pci_fixup_resume_early)				\
++		KEEP(*(.pci_fixup_resume_early))			\
+ 		VMLINUX_SYMBOL(__end_pci_fixups_resume_early) = .;	\
+ 		VMLINUX_SYMBOL(__start_pci_fixups_suspend) = .;		\
+-		*(.pci_fixup_suspend)					\
++		KEEP(*(.pci_fixup_suspend))				\
+ 		VMLINUX_SYMBOL(__end_pci_fixups_suspend) = .;		\
+ 	}								\
+ 									\
+ 	/* Built-in firmware blobs */					\
+ 	.builtin_fw        : AT(ADDR(.builtin_fw) - LOAD_OFFSET) {	\
+ 		VMLINUX_SYMBOL(__start_builtin_fw) = .;			\
+-		*(.builtin_fw)						\
++		KEEP(*(.builtin_fw))					\
+ 		VMLINUX_SYMBOL(__end_builtin_fw) = .;			\
+ 	}								\
+ 									\
+ 	/* RapidIO route ops */						\
+ 	.rio_ops        : AT(ADDR(.rio_ops) - LOAD_OFFSET) {		\
+ 		VMLINUX_SYMBOL(__start_rio_switch_ops) = .;		\
+-		*(.rio_switch_ops)					\
++		KEEP(*(.rio_switch_ops))				\
+ 		VMLINUX_SYMBOL(__end_rio_switch_ops) = .;		\
+ 	}								\
+ 									\
+@@ -276,49 +277,49 @@
+ 	/* Kernel symbol table: Normal symbols */			\
+ 	__ksymtab         : AT(ADDR(__ksymtab) - LOAD_OFFSET) {		\
+ 		VMLINUX_SYMBOL(__start___ksymtab) = .;			\
+-		*(SORT(___ksymtab+*))					\
++		KEEP(*(SORT(___ksymtab+*)))				\
+ 		VMLINUX_SYMBOL(__stop___ksymtab) = .;			\
+ 	}								\
+ 									\
+ 	/* Kernel symbol table: GPL-only symbols */			\
+ 	__ksymtab_gpl     : AT(ADDR(__ksymtab_gpl) - LOAD_OFFSET) {	\
+ 		VMLINUX_SYMBOL(__start___ksymtab_gpl) = .;		\
+-		*(SORT(___ksymtab_gpl+*))				\
++		KEEP(*(SORT(___ksymtab_gpl+*)))				\
+ 		VMLINUX_SYMBOL(__stop___ksymtab_gpl) = .;		\
+ 	}								\
+ 									\
+ 	/* Kernel symbol table: Normal unused symbols */		\
+ 	__ksymtab_unused  : AT(ADDR(__ksymtab_unused) - LOAD_OFFSET) {	\
+ 		VMLINUX_SYMBOL(__start___ksymtab_unused) = .;		\
+-		*(SORT(___ksymtab_unused+*))				\
++		KEEP(*(SORT(___ksymtab_unused+*)))			\
+ 		VMLINUX_SYMBOL(__stop___ksymtab_unused) = .;		\
+ 	}								\
+ 									\
+ 	/* Kernel symbol table: GPL-only unused symbols */		\
+ 	__ksymtab_unused_gpl : AT(ADDR(__ksymtab_unused_gpl) - LOAD_OFFSET) { \
+ 		VMLINUX_SYMBOL(__start___ksymtab_unused_gpl) = .;	\
+-		*(SORT(___ksymtab_unused_gpl+*))			\
++		KEEP(*(SORT(___ksymtab_unused_gpl+*)))			\
+ 		VMLINUX_SYMBOL(__stop___ksymtab_unused_gpl) = .;	\
+ 	}								\
+ 									\
+ 	/* Kernel symbol table: GPL-future-only symbols */		\
+ 	__ksymtab_gpl_future : AT(ADDR(__ksymtab_gpl_future) - LOAD_OFFSET) { \
+ 		VMLINUX_SYMBOL(__start___ksymtab_gpl_future) = .;	\
+-		*(SORT(___ksymtab_gpl_future+*))			\
++		KEEP(*(SORT(___ksymtab_gpl_future+*)))			\
+ 		VMLINUX_SYMBOL(__stop___ksymtab_gpl_future) = .;	\
+ 	}								\
+ 									\
+ 	/* Kernel symbol table: Normal symbols */			\
+ 	__kcrctab         : AT(ADDR(__kcrctab) - LOAD_OFFSET) {		\
+ 		VMLINUX_SYMBOL(__start___kcrctab) = .;			\
+-		*(SORT(___kcrctab+*))					\
++		KEEP(*(SORT(___kcrctab+*)))				\
+ 		VMLINUX_SYMBOL(__stop___kcrctab) = .;			\
+ 	}								\
+ 									\
+ 	/* Kernel symbol table: GPL-only symbols */			\
+ 	__kcrctab_gpl     : AT(ADDR(__kcrctab_gpl) - LOAD_OFFSET) {	\
+ 		VMLINUX_SYMBOL(__start___kcrctab_gpl) = .;		\
+-		*(SORT(___kcrctab_gpl+*))				\
++		KEEP(*(SORT(___kcrctab_gpl+*)))				\
+ 		VMLINUX_SYMBOL(__stop___kcrctab_gpl) = .;		\
+ 	}								\
+ 									\
+@@ -332,14 +333,14 @@
+ 	/* Kernel symbol table: GPL-only unused symbols */		\
+ 	__kcrctab_unused_gpl : AT(ADDR(__kcrctab_unused_gpl) - LOAD_OFFSET) { \
+ 		VMLINUX_SYMBOL(__start___kcrctab_unused_gpl) = .;	\
+-		*(SORT(___kcrctab_unused_gpl+*))			\
++		KEEP(*(SORT(___kcrctab_unused_gpl+*)))			\
+ 		VMLINUX_SYMBOL(__stop___kcrctab_unused_gpl) = .;	\
+ 	}								\
+ 									\
+ 	/* Kernel symbol table: GPL-future-only symbols */		\
+ 	__kcrctab_gpl_future : AT(ADDR(__kcrctab_gpl_future) - LOAD_OFFSET) { \
+ 		VMLINUX_SYMBOL(__start___kcrctab_gpl_future) = .;	\
+-		*(SORT(___kcrctab_gpl_future+*))			\
++		KEEP(*(SORT(___kcrctab_gpl_future+*)))			\
+ 		VMLINUX_SYMBOL(__stop___kcrctab_gpl_future) = .;	\
+ 	}								\
+ 									\
+@@ -362,14 +363,14 @@
+ 	/* Built-in module parameters. */				\
+ 	__param : AT(ADDR(__param) - LOAD_OFFSET) {			\
+ 		VMLINUX_SYMBOL(__start___param) = .;			\
+-		*(__param)						\
++		KEEP(*(__param))					\
+ 		VMLINUX_SYMBOL(__stop___param) = .;			\
+ 	}								\
+ 									\
+ 	/* Built-in module versions. */					\
+ 	__modver : AT(ADDR(__modver) - LOAD_OFFSET) {			\
+ 		VMLINUX_SYMBOL(__start___modver) = .;			\
+-		*(__modver)						\
++		KEEP(*(__modver))					\
+ 		VMLINUX_SYMBOL(__stop___modver) = .;			\
+ 		. = ALIGN((align));					\
+ 		VMLINUX_SYMBOL(__end_rodata) = .;			\
+@@ -429,7 +430,7 @@
+ #define ENTRY_TEXT							\
+ 		ALIGN_FUNCTION();					\
+ 		VMLINUX_SYMBOL(__entry_text_start) = .;			\
+-		*(.entry.text)						\
++		KEEP(*(.entry.text))					\
+ 		VMLINUX_SYMBOL(__entry_text_end) = .;
+ 
+ #ifdef CONFIG_FUNCTION_GRAPH_TRACER
+@@ -457,7 +458,7 @@
+ 	. = ALIGN(align);						\
+ 	__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {		\
+ 		VMLINUX_SYMBOL(__start___ex_table) = .;			\
+-		*(__ex_table)						\
++		KEEP(*(__ex_table))						\
+ 		VMLINUX_SYMBOL(__stop___ex_table) = .;			\
+ 	}
+ 
+@@ -473,7 +474,7 @@
+ #ifdef CONFIG_CONSTRUCTORS
+ #define KERNEL_CTORS()	. = ALIGN(8);			   \
+ 			VMLINUX_SYMBOL(__ctors_start) = .; \
+-			*(.ctors)			   \
++			KEEP(*(.ctors))			   \
+ 			VMLINUX_SYMBOL(__ctors_end) = .;
+ #else
+ #define KERNEL_CTORS()
+@@ -526,7 +527,7 @@
+ #define SBSS(sbss_align)						\
+ 	. = ALIGN(sbss_align);						\
+ 	.sbss : AT(ADDR(.sbss) - LOAD_OFFSET) {				\
+-		*(.sbss)						\
++		*(.sbss .sbss.*)					\
+ 		*(.scommon)						\
+ 	}
+ 
+@@ -544,7 +545,7 @@
+ 		BSS_FIRST_SECTIONS					\
+ 		*(.bss..page_aligned)					\
+ 		*(.dynbss)						\
+-		*(.bss)							\
++		*(.bss .bss.*)						\
+ 		*(COMMON)						\
+ 	}
+ 
+@@ -593,7 +594,7 @@
+ 	. = ALIGN(8);							\
+ 	__bug_table : AT(ADDR(__bug_table) - LOAD_OFFSET) {		\
+ 		VMLINUX_SYMBOL(__start___bug_table) = .;		\
+-		*(__bug_table)						\
++		KEEP(*(__bug_table))					\
+ 		VMLINUX_SYMBOL(__stop___bug_table) = .;			\
+ 	}
+ #else
+@@ -605,7 +606,7 @@
+ 	. = ALIGN(4);							\
+ 	.tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {		\
+ 		VMLINUX_SYMBOL(__tracedata_start) = .;			\
+-		*(.tracedata)						\
++		KEEP(*(.tracedata))					\
+ 		VMLINUX_SYMBOL(__tracedata_end) = .;			\
+ 	}
+ #else
+@@ -622,17 +623,17 @@
+ #define INIT_SETUP(initsetup_align)					\
+ 		. = ALIGN(initsetup_align);				\
+ 		VMLINUX_SYMBOL(__setup_start) = .;			\
+-		*(.init.setup)						\
++		KEEP(*(.init.setup))					\
+ 		VMLINUX_SYMBOL(__setup_end) = .;
+ 
+ #define INIT_CALLS_LEVEL(level)						\
+ 		VMLINUX_SYMBOL(__initcall##level##_start) = .;		\
+-		*(.initcall##level##.init)				\
+-		*(.initcall##level##s.init)				\
++		KEEP(*(.initcall##level##.init))			\
++		KEEP(*(.initcall##level##s.init))			\
+ 
+ #define INIT_CALLS							\
+ 		VMLINUX_SYMBOL(__initcall_start) = .;			\
+-		*(.initcallearly.init)					\
++		KEEP(*(.initcallearly.init))				\
+ 		INIT_CALLS_LEVEL(0)					\
+ 		INIT_CALLS_LEVEL(1)					\
+ 		INIT_CALLS_LEVEL(2)					\
+@@ -646,21 +647,21 @@
+ 
+ #define CON_INITCALL							\
+ 		VMLINUX_SYMBOL(__con_initcall_start) = .;		\
+-		*(.con_initcall.init)					\
++		KEEP(*(.con_initcall.init))				\
+ 		VMLINUX_SYMBOL(__con_initcall_end) = .;
+ 
+ #define SECURITY_INITCALL						\
+ 		VMLINUX_SYMBOL(__security_initcall_start) = .;		\
+-		*(.security_initcall.init)				\
++		KEEP(*(.security_initcall.init))			\
+ 		VMLINUX_SYMBOL(__security_initcall_end) = .;
+ 
+ #ifdef CONFIG_BLK_DEV_INITRD
+ #define INIT_RAM_FS							\
+ 	. = ALIGN(4);							\
+ 	VMLINUX_SYMBOL(__initramfs_start) = .;				\
+-	*(.init.ramfs)							\
++	KEEP(*(.init.ramfs))						\
+ 	. = ALIGN(8);							\
+-	*(.init.ramfs.info)
++	KEEP(*(.init.ramfs.info))
+ #else
+ #define INIT_RAM_FS
+ #endif