[PATCH 4/4] build system: section garbage collection for vmlinux
From: Denys Vlasenko
Date: Tue Sep 11 2007 - 16:22:44 EST
This is the core patch of the series.
It adds CONFIG_DISCARD_UNUSED_SECTIONS,
adds KEEP() directives to linker scripts,
adds custom module linker script which is needed
to avoid having modules with many small sections.
Modules got a bit smaller too, as a result.
This patch is slighty more risky than first three,
probably need to go into -mm first.
It should be safe with CONFIG_DISCARD_UNUSED_SECTIONS off, though.
Signed-off-by: Denys Vlasenko <vda.linux@xxxxxxxxxxxxxx>
--
vda
diff -urpN linux-2.6.23-rc4.gc3/Makefile linux-2.6.23-rc4.gc4/Makefile
--- linux-2.6.23-rc4.gc3/Makefile 2007-08-31 18:58:29.000000000 +0100
+++ linux-2.6.23-rc4.gc4/Makefile 2007-09-11 21:12:31.000000000 +0100
@@ -508,6 +508,11 @@ CFLAGS += $(call cc-option, -fn
NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
CHECKFLAGS += $(NOSTDINC_FLAGS)
+ifdef CONFIG_DISCARD_UNUSED_SECTIONS
+CFLAGS += $(call cc-option, -ffunction-sections -fdata-sections)
+LDFLAGS_vmlinux += --gc-sections --print-gc-sections -Map vmlinux.map
+endif
+
# warn about C99 declaration after statement
CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
diff -urpN linux-2.6.23-rc4.gc3/arch/frv/Makefile linux-2.6.23-rc4.gc4/arch/frv/Makefile
--- linux-2.6.23-rc4.gc3/arch/frv/Makefile 2007-08-31 18:31:02.000000000 +0100
+++ linux-2.6.23-rc4.gc4/arch/frv/Makefile 2007-09-11 20:34:22.000000000 +0100
@@ -52,7 +52,9 @@ endif
#LDFLAGS_vmlinux := -Map linkmap.txt
-ifdef CONFIG_GC_SECTIONS
+# Is this needed? We do this already in kernel's top-level Makefile.
+# $(LINKFLAGS) seems to be unused.
+ifdef CONFIG_DISCARD_UNUSED_SECTIONS
CFLAGS += -ffunction-sections -fdata-sections
LINKFLAGS += --gc-sections
endif
diff -urpN linux-2.6.23-rc4.gc3/arch/x86_64/kernel/modules.lds linux-2.6.23-rc4.gc4/arch/x86_64/kernel/modules.lds
--- linux-2.6.23-rc4.gc3/arch/x86_64/kernel/modules.lds 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.23-rc4.gc4/arch/x86_64/kernel/modules.lds 2007-09-11 21:19:20.000000000 +0100
@@ -0,0 +1,123 @@
+OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64", "elf64-x86-64")
+OUTPUT_ARCH(i386:x86-64)
+
+/*
+This linker script is used if CONFIG_DISCARD_UNUSED_SECTIONS=y.
+We are trying to minimize number of sections in .ko file
+by coalescing .text.x, rodata.x, .data.x and bss.x input
+sections into one output section.
+
+This script may be usable without CONFIG_DISCARD_UNUSED_SECTIONS too.
+
+Kernel module loader (kernel/module.c) needs to see the following sections:
+
+.init*
+.exit*
+.gnu.linkonce.this_module
+.percpu.data
+.modinfo
+__ksymtab_gpl_future
+__ksymtab_gpl
+__ksymtab_unused_gpl
+__ksymtab_unused
+__ksymtab
+__kcrctab_gpl_future
+__kcrctab_gpl
+__kcrctab_unused_gpl
+__kcrctab_unused
+__kcrctab
+__param
+__ex_table
+__obsparm
+__versions
+.debug (?!)
+$ARCH_UNWIND_SECTION_NAME (none for x86_64 yet)
+
+They must not be coalesced into sections with other names.
+
+*/
+
+SECTIONS
+{
+ /* ro, code */
+
+ /* .fixup and .altinstr_replacement work just fine
+ * without dedicated sections */
+ .text : {
+ *(SORT_BY_ALIGNMENT(.text*))
+ /* __ex_table points here */
+ *(SORT_BY_ALIGNMENT(.fixup*))
+ /* .altinstructions points here */
+ *(SORT_BY_ALIGNMENT(.altinstr_replacement*))
+ }
+ /* only if CONFIG_MODULE_UNLOAD */
+ .exit.text : { *(SORT_BY_ALIGNMENT(.exit.text)) }
+ /* end CONFIG_MODULE_UNLOAD */
+
+ /* ro, data */
+
+ .rodata : { *(SORT_BY_ALIGNMENT(.rodata*)) }
+ /* Kernel searches through this table when it needs to handle an exception */
+ __ex_table : { *(__ex_table*) }
+ /* These two tables are not currently handled by in-kernel module loader,
+ * but likely will be in future kernels */
+ .altinstructions : { *(.altinstructions*) }
+ .smp_locks : { *(.smp_locks*) }
+ /* Used by depmod in order to generate modules.dep, modules.symbols */
+ __ksymtab_strings : { *(SORT_BY_ALIGNMENT(__ksymtab_strings)) }
+ /* EXPORT_SYMBOLs exported in this module */
+ __ksymtab_gpl_future : { *(__ksymtab_gpl_future) }
+ __ksymtab_gpl : { *(__ksymtab_gpl) }
+ __ksymtab_unused_gpl : { *(__ksymtab_unused_gpl) }
+ __ksymtab_unused : { *(__ksymtab_unused) }
+ __ksymtab : { *(__ksymtab) }
+ /* only if CONFIG_MODVERSIONS */
+ __kcrctab_gpl_future : { *(__kcrctab_gpl_future) }
+ __kcrctab_gpl : { *(__kcrctab_gpl) }
+ __kcrctab_unused_gpl : { *(__kcrctab_unused_gpl) }
+ __kcrctab_unused : { *(__kcrctab_unused) }
+ __kcrctab : { *(__kcrctab) }
+ /* from *.mod.c: const struct modversion_info ____versions[] */
+ __versions : { *(__versions) }
+ /* end CONFIG_MODVERSIONS */
+ __param : { *(.__param) }
+ __obsparm : { *(.__obsparm) }
+ /* from *.mod.c: const char __module_depends[] "depends=mod1,mod2" */
+ .modinfo : { *(SORT_BY_ALIGNMENT(.modinfo)) }
+ /* ld segfaults if we give it --build-id and then discard this section */
+ .note.gnu.build-id : { *(.note.gnu.build-id) }
+
+ /* rw, data */
+
+ .data : {
+ *(SORT_BY_ALIGNMENT(.cacheline_aligned.data))
+ *(SORT_BY_ALIGNMENT(.data*))
+ *(SORT_BY_ALIGNMENT(.read_mostly.data))
+ }
+ /* from *.mod.c: struct module __this_module */
+ .gnu.linkonce.this_module : { *(.gnu.linkonce.this_module) }
+ /* only if CONFIG_SMP */
+ .percpu.data : { *(SORT_BY_ALIGNMENT(.percpu.data)) }
+ /* end CONFIG_SMP */
+ /* only if CONFIG_MODULE_UNLOAD */
+ .exit.data : { *(SORT_BY_ALIGNMENT(.exit.data)) }
+ /* end CONFIG_MODULE_UNLOAD */
+
+ /* rw, data initialized to 0 */
+
+ .bss : { *(SORT_BY_ALIGNMENT(.bss*)) }
+
+ /* init code/data. discarded at the end of sys_init_module() */
+
+ .init.text : { *(SORT_BY_ALIGNMENT(.init.text)) }
+ .init.data : { *(SORT_BY_ALIGNMENT(.init.data)) }
+
+ /* Be bold and resist the temptation to pull junk "by default" */
+
+ /DISCARD/ : { *(*) }
+
+ /* If you are going to revive these, please add comment why it is needed */
+ /* .debug : { *(.debug) } */
+ /* .comment : { *(.comment) } */
+ /* .note.GNU-stack : { *(.note.GNU-stack) } */
+}
diff -urpN linux-2.6.23-rc4.gc3/arch/x86_64/kernel/vmlinux.lds.S linux-2.6.23-rc4.gc4/arch/x86_64/kernel/vmlinux.lds.S
--- linux-2.6.23-rc4.gc3/arch/x86_64/kernel/vmlinux.lds.S 2007-09-11 20:30:02.000000000 +0100
+++ linux-2.6.23-rc4.gc4/arch/x86_64/kernel/vmlinux.lds.S 2007-09-11 20:34:22.000000000 +0100
@@ -28,14 +28,14 @@ SECTIONS
_text = .; /* Text and read-only data */
.text : AT(ADDR(.text) - LOAD_OFFSET) {
/* First the code that has to be first for bootstrapping */
- *(.head.text)
+ KEEP(*(.head.text))
_stext = .;
/* Then the rest */
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
- *(.fixup)
+ *(.fixup) /* no need to KEEP, every .fixup is referenced by __ex_table */
*(.gnu.warning)
} :text = 0x9090
/* out-of-line lock text */
@@ -44,8 +44,9 @@ SECTIONS
_etext = .; /* End of text section */
. = ALIGN(16); /* Exception table */
+ /* Points to potentially-faulting insns and corresponding .fixups */
__start___ex_table = .;
- __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { *(__ex_table) }
+ __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { KEEP(*(__ex_table)) }
__stop___ex_table = .;
NOTES :text :note
@@ -91,34 +92,34 @@ SECTIONS
#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)
. = VSYSCALL_ADDR;
- .vsyscall_0 : AT(VSYSCALL_PHYS_ADDR) { *(.vsyscall_0) } :user
+ .vsyscall_0 : AT(VSYSCALL_PHYS_ADDR) { KEEP(*(.vsyscall_0)) } :user
__vsyscall_0 = VSYSCALL_VIRT_ADDR;
. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
- .vsyscall_fn : AT(VLOAD(.vsyscall_fn)) { *(.vsyscall_fn) }
+ .vsyscall_fn : AT(VLOAD(.vsyscall_fn)) { KEEP(*(.vsyscall_fn)) }
. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
.vsyscall_gtod_data : AT(VLOAD(.vsyscall_gtod_data))
- { *(.vsyscall_gtod_data) }
+ { KEEP(*(.vsyscall_gtod_data)) }
vsyscall_gtod_data = VVIRT(.vsyscall_gtod_data);
.vsyscall_clock : AT(VLOAD(.vsyscall_clock))
- { *(.vsyscall_clock) }
+ { KEEP(*(.vsyscall_clock)) }
vsyscall_clock = VVIRT(.vsyscall_clock);
- .vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1))
- { *(.vsyscall_1) }
- .vsyscall_2 ADDR(.vsyscall_0) + 2048: AT(VLOAD(.vsyscall_2))
- { *(.vsyscall_2) }
+ .vsyscall_1 VSYSCALL_ADDR + 1024: AT(VLOAD(.vsyscall_1))
+ { KEEP(*(.vsyscall_1)) }
+ .vsyscall_2 VSYSCALL_ADDR + 2048: AT(VLOAD(.vsyscall_2))
+ { KEEP(*(.vsyscall_2)) }
- .vgetcpu_mode : AT(VLOAD(.vgetcpu_mode)) { *(.vgetcpu_mode) }
+ .vgetcpu_mode : AT(VLOAD(.vgetcpu_mode)) { KEEP(*(.vgetcpu_mode)) }
vgetcpu_mode = VVIRT(.vgetcpu_mode);
. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);
- .jiffies : AT(VLOAD(.jiffies)) { *(.jiffies) }
+ .jiffies : AT(VLOAD(.jiffies)) { KEEP(*(.jiffies)) }
jiffies = VVIRT(.jiffies);
- .vsyscall_3 ADDR(.vsyscall_0) + 3072: AT(VLOAD(.vsyscall_3))
- { *(.vsyscall_3) }
+ .vsyscall_3 VSYSCALL_ADDR + 3072: AT(VLOAD(.vsyscall_3))
+ { KEEP(*(.vsyscall_3)) }
. = VSYSCALL_VIRT_ADDR + 4096;
@@ -141,11 +142,12 @@ SECTIONS
}
/* might get freed after init */
+
. = ALIGN(4096);
__smp_alt_begin = .;
__smp_locks = .;
.smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
- *(.smp_locks)
+ KEEP(*(.smp_locks)) /* points to lock prefixes */
}
__smp_locks_end = .;
. = ALIGN(4096);
@@ -155,15 +157,15 @@ SECTIONS
__init_begin = .;
.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
_sinittext = .;
- *(.init.text)
+ *(.init.text) /* no need to KEEP */
_einittext = .;
}
__initdata_begin = .;
- .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { *(.init.data) }
+ .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { *(.init.data) } /* no need to KEEP */
__initdata_end = .;
. = ALIGN(16);
__setup_start = .;
- .init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) { *(.init.setup) }
+ .init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) { KEEP(*(.init.setup)) } /* obsolete_checksetup() walks it */
__setup_end = .;
__initcall_start = .;
.initcall.init : AT(ADDR(.initcall.init) - LOAD_OFFSET) {
@@ -172,34 +174,34 @@ SECTIONS
__initcall_end = .;
__con_initcall_start = .;
.con_initcall.init : AT(ADDR(.con_initcall.init) - LOAD_OFFSET) {
- *(.con_initcall.init)
+ KEEP(*(.con_initcall.init)) /* console_init() walks it */
}
__con_initcall_end = .;
SECURITY_INIT
. = ALIGN(8);
__alt_instructions = .;
.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
- *(.altinstructions)
+ KEEP(*(.altinstructions)) /* alternative_instructions() walks it */
}
__alt_instructions_end = .;
.altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
- *(.altinstr_replacement)
+ KEEP(*(.altinstr_replacement))
}
- /* .exit.text is discard at runtime, not link time, to deal with references
+ /* .exit.text is discarded at runtime, not link time, to deal with references
from .altinstructions and .eh_frame */
.exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) { *(.exit.text) }
.exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) { *(.exit.data) }
/* vdso blob that is mapped into user space */
vdso_start = . ;
- .vdso : AT(ADDR(.vdso) - LOAD_OFFSET) { *(.vdso) }
+ .vdso : AT(ADDR(.vdso) - LOAD_OFFSET) { KEEP(*(.vdso)) }
. = ALIGN(4096);
vdso_end = .;
#ifdef CONFIG_BLK_DEV_INITRD
. = ALIGN(4096);
__initramfs_start = .;
- .init.ramfs : AT(ADDR(.init.ramfs) - LOAD_OFFSET) { *(.init.ramfs) }
+ .init.ramfs : AT(ADDR(.init.ramfs) - LOAD_OFFSET) { KEEP(*(.init.ramfs)) }
__initramfs_end = .;
#endif
@@ -210,7 +212,7 @@ SECTIONS
. = ALIGN(4096);
__nosave_begin = .;
- .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) { *(.nosave.data) }
+ .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) { *(.nosave.data) } /* not saved by suspend */
. = ALIGN(4096);
__nosave_end = .;
@@ -218,6 +220,7 @@ SECTIONS
.bss : AT(ADDR(.bss) - LOAD_OFFSET) {
*(.bss.k.page_aligned)
*(.bss)
+ *(SORT_BY_ALIGNMENT(.bss.*))
}
__bss_stop = .;
diff -urpN linux-2.6.23-rc4.gc3/include/asm-generic/vmlinux.lds.h linux-2.6.23-rc4.gc4/include/asm-generic/vmlinux.lds.h
--- linux-2.6.23-rc4.gc3/include/asm-generic/vmlinux.lds.h 2007-09-11 20:30:02.000000000 +0100
+++ linux-2.6.23-rc4.gc4/include/asm-generic/vmlinux.lds.h 2007-09-11 20:34:22.000000000 +0100
@@ -6,19 +6,26 @@
#define VMLINUX_SYMBOL(_sym_) _sym_
#endif
+#ifndef CONFIG_DISCARD_UNUSED_SECTIONS
+/* Don't confuse old ld with new stuff */
+#define KEEP(x) x
+#define SORT_BY_ALIGNMENT(x) x
+#endif
+
/* Align . to a 8 byte boundary equals to maximum function alignment. */
#define ALIGN_FUNCTION() . = ALIGN(8)
/* .data section */
#define DATA_DATA \
*(.data) \
+ *(SORT_BY_ALIGNMENT(.data.*)) \
*(.init.refok.data)
#define RO_DATA(align) \
. = ALIGN((align)); \
.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start_rodata) = .; \
- *(.rodata) *(.rodata.*) \
+ *(.rodata) *(SORT_BY_ALIGNMENT(.rodata.*)) \
*(__vermagic) /* Kernel version magic */ \
} \
\
@@ -28,109 +35,110 @@
\
/* PCI quirks */ \
.pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \
+ /* walked by pci_fixup_device() */ \
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) = .; \
} \
\
/* RapidIO route ops */ \
.rio_route : AT(ADDR(.rio_route) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start_rio_route_ops) = .; \
- *(.rio_route_ops) \
+ KEEP(*(.rio_route_ops)) \
VMLINUX_SYMBOL(__end_rio_route_ops) = .; \
} \
\
/* Kernel symbol table: Normal symbols */ \
__ksymtab : AT(ADDR(__ksymtab) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___ksymtab) = .; \
- *(__ksymtab) \
+ KEEP(*(__ksymtab)) \
VMLINUX_SYMBOL(__stop___ksymtab) = .; \
} \
\
/* Kernel symbol table: GPL-only symbols */ \
__ksymtab_gpl : AT(ADDR(__ksymtab_gpl) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___ksymtab_gpl) = .; \
- *(__ksymtab_gpl) \
+ KEEP(*(__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) = .; \
- *(__ksymtab_unused) \
+ KEEP(*(__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) = .; \
- *(__ksymtab_unused_gpl) \
+ KEEP(*(__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) = .; \
- *(__ksymtab_gpl_future) \
+ KEEP(*(__ksymtab_gpl_future)) \
VMLINUX_SYMBOL(__stop___ksymtab_gpl_future) = .; \
} \
\
/* Kernel symbol table: Normal symbols */ \
__kcrctab : AT(ADDR(__kcrctab) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___kcrctab) = .; \
- *(__kcrctab) \
+ KEEP(*(__kcrctab)) \
VMLINUX_SYMBOL(__stop___kcrctab) = .; \
} \
\
/* Kernel symbol table: GPL-only symbols */ \
__kcrctab_gpl : AT(ADDR(__kcrctab_gpl) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___kcrctab_gpl) = .; \
- *(__kcrctab_gpl) \
+ KEEP(*(__kcrctab_gpl)) \
VMLINUX_SYMBOL(__stop___kcrctab_gpl) = .; \
} \
\
/* Kernel symbol table: Normal unused symbols */ \
__kcrctab_unused : AT(ADDR(__kcrctab_unused) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___kcrctab_unused) = .; \
- *(__kcrctab_unused) \
+ KEEP(*(__kcrctab_unused)) \
VMLINUX_SYMBOL(__stop___kcrctab_unused) = .; \
} \
\
/* Kernel symbol table: GPL-only unused symbols */ \
__kcrctab_unused_gpl : AT(ADDR(__kcrctab_unused_gpl) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___kcrctab_unused_gpl) = .; \
- *(__kcrctab_unused_gpl) \
+ KEEP(*(__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) = .; \
- *(__kcrctab_gpl_future) \
+ KEEP(*(__kcrctab_gpl_future)) \
VMLINUX_SYMBOL(__stop___kcrctab_gpl_future) = .; \
} \
\
/* Kernel symbol table: strings */ \
__ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \
- *(__ksymtab_strings) \
+ KEEP(*(__ksymtab_strings)) \
} \
\
/* Built-in module parameters. */ \
__param : AT(ADDR(__param) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___param) = .; \
- *(__param) \
+ KEEP(*(__param)) \
VMLINUX_SYMBOL(__stop___param) = .; \
VMLINUX_SYMBOL(__end_rodata) = .; \
} \
@@ -144,7 +152,7 @@
#define SECURITY_INIT \
.security_initcall.init : AT(ADDR(.security_initcall.init) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__security_initcall_start) = .; \
- *(.security_initcall.init) \
+ KEEP(*(.security_initcall.init)) \
VMLINUX_SYMBOL(__security_initcall_end) = .; \
}
@@ -153,6 +161,7 @@
#define TEXT_TEXT \
ALIGN_FUNCTION(); \
*(.text) \
+ *(SORT_BY_ALIGNMENT(.text.*)) \
*(.init.refok.text)
/* sched.text is aling to function alignment to secure we have same
@@ -231,23 +240,23 @@
}
#define INITCALLS \
- *(.initcall0.init) \
- *(.initcall0s.init) \
- *(.initcall1.init) \
- *(.initcall1s.init) \
- *(.initcall2.init) \
- *(.initcall2s.init) \
- *(.initcall3.init) \
- *(.initcall3s.init) \
- *(.initcall4.init) \
- *(.initcall4s.init) \
- *(.initcall5.init) \
- *(.initcall5s.init) \
- *(.initcallrootfs.init) \
- *(.initcall6.init) \
- *(.initcall6s.init) \
- *(.initcall7.init) \
- *(.initcall7s.init)
+ KEEP(*(.initcall0.init)) /* do_initcalls() walks them */ \
+ KEEP(*(.initcall0s.init)) \
+ KEEP(*(.initcall1.init)) \
+ KEEP(*(.initcall1s.init)) \
+ KEEP(*(.initcall2.init)) \
+ KEEP(*(.initcall2s.init)) \
+ KEEP(*(.initcall3.init)) \
+ KEEP(*(.initcall3s.init)) \
+ KEEP(*(.initcall4.init)) \
+ KEEP(*(.initcall4s.init)) \
+ KEEP(*(.initcall5.init)) \
+ KEEP(*(.initcall5s.init)) \
+ KEEP(*(.initcallrootfs.init)) \
+ KEEP(*(.initcall6.init)) \
+ KEEP(*(.initcall6s.init)) \
+ KEEP(*(.initcall7.init)) \
+ KEEP(*(.initcall7s.init))
#define PERCPU(align) \
. = ALIGN(align); \
diff -urpN linux-2.6.23-rc4.gc3/init/Kconfig linux-2.6.23-rc4.gc4/init/Kconfig
--- linux-2.6.23-rc4.gc3/init/Kconfig 2007-08-31 18:31:05.000000000 +0100
+++ linux-2.6.23-rc4.gc4/init/Kconfig 2007-09-11 21:14:46.000000000 +0100
@@ -347,6 +347,23 @@ config CC_OPTIMIZE_FOR_SIZE
If unsure, say N.
+config DISCARD_UNUSED_SECTIONS
+ bool "Discard unused code/data sections (DANGEROUS)"
+ default n
+ depends on EXPERIMENTAL
+ help
+ Enabling this option will pass --ffunction-sections -fdata-sections
+ to gcc and --gc-sections to ld, resulting in a smaller kernel.
+
+ WARNING: --gc-sections support is very new and considered highly
+ experimental for now. You need at least binutils 2.18,
+ and even then surprises are likely.
+
+ This option also requires architecture-specific changes.
+ Currently working architectures: x86_64
+
+ If unsure, say N.
+
config SYSCTL
bool
diff -urpN linux-2.6.23-rc4.gc3/scripts/Makefile.modpost linux-2.6.23-rc4.gc4/scripts/Makefile.modpost
--- linux-2.6.23-rc4.gc3/scripts/Makefile.modpost 2007-08-31 18:31:05.000000000 +0100
+++ linux-2.6.23-rc4.gc4/scripts/Makefile.modpost 2007-09-11 20:33:24.000000000 +0100
@@ -97,9 +97,15 @@ $(modules:.ko=.mod.o): %.mod.o: %.mod.c
targets += $(modules:.ko=.mod.o)
# Step 6), final link of the modules
+ifdef CONFIG_DISCARD_UNUSED_SECTIONS
+quiet_cmd_ld_ko_o = LD [M] $@
+ cmd_ld_ko_o = $(LD) -r -T arch/$(ARCH)/kernel/modules.lds $(LDFLAGS) $(LDFLAGS_MODULE) -o $@ -Map $@.map \
+ $(filter-out FORCE,$^)
+else
quiet_cmd_ld_ko_o = LD [M] $@
cmd_ld_ko_o = $(LD) -r $(LDFLAGS) $(LDFLAGS_MODULE) -o $@ \
$(filter-out FORCE,$^)
+endif
$(modules): %.ko :%.o %.mod.o FORCE
$(call if_changed,ld_ko_o)