| Message ID | 1444622356-8263-1-git-send-email-yalin.wang2010@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 12 October 2015 at 05:59, yalin wang <yalin.wang2010@gmail.com> wrote: > This attribute can make init data to be into .initbss section, > this will make the data to be NO_BITS in vmlinux, can shrink the > Image file size, and speed up the boot up time. > > Signed-off-by: yalin wang <yalin.wang2010@gmail.com> > --- > arch/arm/kernel/vmlinux.lds.S | 2 +- > arch/arm/mm/init.c | 1 + > include/asm-generic/sections.h | 1 + > include/asm-generic/vmlinux.lds.h | 11 ++++++++++- > include/linux/init.h | 1 + > include/linux/mm.h | 4 +++- > 6 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S > index 8b60fde..ad6d740 100644 > --- a/arch/arm/kernel/vmlinux.lds.S > +++ b/arch/arm/kernel/vmlinux.lds.S > @@ -330,7 +330,7 @@ SECTIONS > } > #endif > > - BSS_SECTION(0, 0, 0) > + BSS_SECTION(0, 0, 0, 0) > _end = .; > > STABS_DEBUG > diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c > index 8a63b4c..50b881e 100644 > --- a/arch/arm/mm/init.c > +++ b/arch/arm/mm/init.c > @@ -722,6 +722,7 @@ void free_initmem(void) > free_tcmmem(); > > poison_init_mem(__init_begin, __init_end - __init_begin); > + poison_init_mem(__initbss_start, __initbss_start - __initbss_end); > if (!machine_is_integrator() && !machine_is_cintegrator()) > free_initmem_default(-1); > } > diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h > index b58fd66..a63ebe9 100644 > --- a/include/asm-generic/sections.h > +++ b/include/asm-generic/sections.h > @@ -29,6 +29,7 @@ extern char _text[], _stext[], _etext[]; > extern char _data[], _sdata[], _edata[]; > extern char __bss_start[], __bss_stop[]; > extern char __init_begin[], __init_end[]; > +extern char __initbss_start[], __initbss_end[]; > extern char _sinittext[], _einittext[]; > extern char _end[]; > extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[]; > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > index c4bd0e2..b3db62d 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -574,6 +574,14 @@ > *(COMMON) \ > } > > +#define INITBSS(initbss_align) \ > + . = ALIGN(initbss_align); \ > + .initbss : AT(ADDR(.initbss) - LOAD_OFFSET) { \ > + VMLINUX_SYMBOL(__initbss_start) = .; \ > + *(.bss.init.data) \ > + VMLINUX_SYMBOL(__initbss_end) = .; \ > + } > + > /* > * DWARF debug sections. > * Symbols in the DWARF debugging sections are relative to > @@ -831,10 +839,11 @@ > INIT_RAM_FS \ > } > > -#define BSS_SECTION(sbss_align, bss_align, stop_align) \ > +#define BSS_SECTION(sbss_align, bss_align, initbss_align, stop_align) \ > . = ALIGN(sbss_align); \ > VMLINUX_SYMBOL(__bss_start) = .; \ > SBSS(sbss_align) \ > BSS(bss_align) \ > + INITBSS(initbss_align) \ > . = ALIGN(stop_align); \ > VMLINUX_SYMBOL(__bss_stop) = .; > diff --git a/include/linux/init.h b/include/linux/init.h > index b449f37..f2960b2 100644 > --- a/include/linux/init.h > +++ b/include/linux/init.h > @@ -41,6 +41,7 @@ > discard it in modules) */ > #define __init __section(.init.text) __cold notrace > #define __initdata __section(.init.data) > +#define __initbss __section(.bss.init.data) Shouldn't this be .init.bss ? > #define __initconst __constsection(.init.rodata) > #define __exitdata __section(.exit.data) > #define __exit_call __used __section(.exitcall.exit) > diff --git a/include/linux/mm.h b/include/linux/mm.h > index d30eea3..1f266f7 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -21,6 +21,7 @@ > #include <linux/resource.h> > #include <linux/page_ext.h> > #include <linux/err.h> > +#include <asm/sections.h> > > struct mempolicy; > struct anon_vma; > @@ -1722,10 +1723,11 @@ static inline void mark_page_reserved(struct page *page) > */ > static inline unsigned long free_initmem_default(int poison) > { > - extern char __init_begin[], __init_end[]; > > return free_reserved_area(&__init_begin, &__init_end, > poison, "unused kernel"); > + return free_reserved_area(&__initbss_start, &__initbss_end, > + poison, "unused kernel"); You obviously have not tested this code, since the first return makes the second unreachable. So you will need to put __initbss annotations all over the tree to actually populate and then free this section (after you have fixed your code). Before we do that, could we have an estimate of how much memory it actually frees up, especially since the zImage compression should ensure that zero initialized PROGBITS .data does not take very much additional space in the first place.
> On Oct 12, 2015, at 16:22, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > > On 12 October 2015 at 05:59, yalin wang <yalin.wang2010@gmail.com> wrote: >> This attribute can make init data to be into .initbss section, >> this will make the data to be NO_BITS in vmlinux, can shrink the >> Image file size, and speed up the boot up time. >> >> Signed-off-by: yalin wang <yalin.wang2010@gmail.com> >> --- >> arch/arm/kernel/vmlinux.lds.S | 2 +- >> arch/arm/mm/init.c | 1 + >> include/asm-generic/sections.h | 1 + >> include/asm-generic/vmlinux.lds.h | 11 ++++++++++- >> include/linux/init.h | 1 + >> include/linux/mm.h | 4 +++- >> 6 files changed, 17 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S >> index 8b60fde..ad6d740 100644 >> --- a/arch/arm/kernel/vmlinux.lds.S >> +++ b/arch/arm/kernel/vmlinux.lds.S >> @@ -330,7 +330,7 @@ SECTIONS >> } >> #endif >> >> - BSS_SECTION(0, 0, 0) >> + BSS_SECTION(0, 0, 0, 0) >> _end = .; >> >> STABS_DEBUG >> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c >> index 8a63b4c..50b881e 100644 >> --- a/arch/arm/mm/init.c >> +++ b/arch/arm/mm/init.c >> @@ -722,6 +722,7 @@ void free_initmem(void) >> free_tcmmem(); >> >> poison_init_mem(__init_begin, __init_end - __init_begin); >> + poison_init_mem(__initbss_start, __initbss_start - __initbss_end); >> if (!machine_is_integrator() && !machine_is_cintegrator()) >> free_initmem_default(-1); >> } >> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h >> index b58fd66..a63ebe9 100644 >> --- a/include/asm-generic/sections.h >> +++ b/include/asm-generic/sections.h >> @@ -29,6 +29,7 @@ extern char _text[], _stext[], _etext[]; >> extern char _data[], _sdata[], _edata[]; >> extern char __bss_start[], __bss_stop[]; >> extern char __init_begin[], __init_end[]; >> +extern char __initbss_start[], __initbss_end[]; >> extern char _sinittext[], _einittext[]; >> extern char _end[]; >> extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[]; >> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h >> index c4bd0e2..b3db62d 100644 >> --- a/include/asm-generic/vmlinux.lds.h >> +++ b/include/asm-generic/vmlinux.lds.h >> @@ -574,6 +574,14 @@ >> *(COMMON) \ >> } >> >> +#define INITBSS(initbss_align) \ >> + . = ALIGN(initbss_align); \ >> + .initbss : AT(ADDR(.initbss) - LOAD_OFFSET) { \ >> + VMLINUX_SYMBOL(__initbss_start) = .; \ >> + *(.bss.init.data) \ >> + VMLINUX_SYMBOL(__initbss_end) = .; \ >> + } >> + >> /* >> * DWARF debug sections. >> * Symbols in the DWARF debugging sections are relative to >> @@ -831,10 +839,11 @@ >> INIT_RAM_FS \ >> } >> >> -#define BSS_SECTION(sbss_align, bss_align, stop_align) \ >> +#define BSS_SECTION(sbss_align, bss_align, initbss_align, stop_align) \ >> . = ALIGN(sbss_align); \ >> VMLINUX_SYMBOL(__bss_start) = .; \ >> SBSS(sbss_align) \ >> BSS(bss_align) \ >> + INITBSS(initbss_align) \ >> . = ALIGN(stop_align); \ >> VMLINUX_SYMBOL(__bss_stop) = .; >> diff --git a/include/linux/init.h b/include/linux/init.h >> index b449f37..f2960b2 100644 >> --- a/include/linux/init.h >> +++ b/include/linux/init.h >> @@ -41,6 +41,7 @@ >> discard it in modules) */ >> #define __init __section(.init.text) __cold notrace >> #define __initdata __section(.init.data) >> +#define __initbss __section(.bss.init.data) > > Shouldn't this be .init.bss ? > >> #define __initconst __constsection(.init.rodata) >> #define __exitdata __section(.exit.data) >> #define __exit_call __used __section(.exitcall.exit) >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index d30eea3..1f266f7 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -21,6 +21,7 @@ >> #include <linux/resource.h> >> #include <linux/page_ext.h> >> #include <linux/err.h> >> +#include <asm/sections.h> >> >> struct mempolicy; >> struct anon_vma; >> @@ -1722,10 +1723,11 @@ static inline void mark_page_reserved(struct page *page) >> */ >> static inline unsigned long free_initmem_default(int poison) >> { >> - extern char __init_begin[], __init_end[]; >> >> return free_reserved_area(&__init_begin, &__init_end, >> poison, "unused kernel"); >> + return free_reserved_area(&__initbss_start, &__initbss_end, >> + poison, "unused kernel"); > > You obviously have not tested this code, since the first return makes > the second unreachable. > > So you will need to put __initbss annotations all over the tree to > actually populate and then free this section (after you have fixed > your code). Before we do that, could we have an estimate of how much > memory it actually frees up, especially since the zImage compression > should ensure that zero initialized PROGBITS .data does not take very > much additional space in the first place. > > -- > Ard. yeah, I just compile it , not test it . because i need replace lots of __initdata variable to __initbss first . i don’t think zImage compression can shrink zero data in .data section , in current __initdata implementation , the zero initialized data are mixed with non-zero data, for example: int a = 20 __initdata; int b __initdata; // zero initialized data int c = 30 __initdata; so the zero data are not in a contineous memory area, compress will not benefit from this scenario, and on some platforms like arm64 , don’t compress compress zImage , i will make a test in some time later, and send out the result to see if this method is better . Thanks
On Monday 12 October 2015 11:59:16 yalin wang wrote: > This attribute can make init data to be into .initbss section, > this will make the data to be NO_BITS in vmlinux, can shrink the > Image file size, and speed up the boot up time. > > Signed-off-by: yalin wang <yalin.wang2010@gmail.com> Do you have an estimate of how much it gains? In multi_v7_defconfig, I see a total of 3367 symbols with 406016 bytes init.data, but only 348 bytes of those are in zero-initialized symbols. Arnd
> --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > > -#define BSS_SECTION(sbss_align, bss_align, stop_align) \ > +#define BSS_SECTION(sbss_align, bss_align, initbss_align, stop_align) \ A few comments: 1) - please align the backslash at the end of the line with the backslash above it. 2) - you need to fix all the remaining users of BSS_SECTION. 3) - do we really need the flexibility to specify an alignment (stop_align)? If not - drop the extra argument. Sam
On Tuesday 13 October 2015 15:33:10 yalin wang wrote: > > > On Oct 13, 2015, at 04:04, Sam Ravnborg <sam@ravnborg.org> wrote: > > > >> --- a/include/asm-generic/vmlinux.lds.h > >> +++ b/include/asm-generic/vmlinux.lds.h > >> > >> -#define BSS_SECTION(sbss_align, bss_align, stop_align) \ > >> +#define BSS_SECTION(sbss_align, bss_align, initbss_align, stop_align) \ > > > > A few comments: > > > > 1) - please align the backslash at the end of the > > line with the backslash above it. > > 2) - you need to fix all the remaining users of BSS_SECTION. > > 3) - do we really need the flexibility to specify an alignment (stop_align)? > > If not - drop the extra argument. > > > > Sam > i change lots of __initdata to __initbss to test it on ARM arch, > Ok, I found my mistake in the script I used to calculate the savings, here is the correct output showing all uninitialized variables in multi_v7_defconfig: 4 done.44688 1024 boot_command_line 1024 tmp_cmdline.44689 4 late_time_init 4 root_mount_data 4 root_fs_names 4 rd_doload 4 root_delay 64 saved_root_name 4 root_device_name 4 message 4 byte_count 4 victim 4 collected 8 this_header 4 state 4 collect 4 remains 4 next_state 8 header_buf 8 next_header 4 do_retain_initrd 4 name_len 4 body_len 4 gid 4 uid 4 mtime 4 wfd 4 vcollected 4 ino 4 mode 4 nlink 4 major 4 minor 4 rdev 4 symlink_buf 4 name_buf 64 msg_buf.29770 128 head 4 machine_desc 4 usermem.34390 4 __atags_pointer 1024 cmd_line 1024 default_command_line 1536 atags_copy 4 dma_mmu_remap_num 64 dma_mmu_remap 4 phys_initrd_start 4024 phys_initrd_size 4096 bm_pte 4 ecc_mask 4 initial_pmd_value 4 arm_lowmem_limit 24 s5p_mfc_mem 28 tx_pad_name 4 use_gptimer_clksrc 4 omap_table_init 4 mpurate 4 am35xx_aes_hwmod_ocp_ifs 4 am35xx_sham_hwmod_ocp_ifs 4 dra72x_hwmod_ocp_ifs 4 rx51_vibra_data 4 num_special_pds 128 special_pds 4 main_extable_sort_needed 4 new_log_buf_len 24 opts.36513 512 smap.22469 512 dmap.22470 64 group_map.22521 64 group_cnt.22522 4 pcpu_chosen_fc 4 vmlist 4 vm_init_off.26867 4 reset_managed_pages_done 116 boot_kmem_cache_node.32827 116 boot_kmem_cache.32826 4 dhash_entries 4 ihash_entries 4 mhash_entries 4 mphash_entries 256 nfs_root_parms 1028 nfs_export_path 1028 nfs_root_device 4 gic_cnt 4 threshold_index 4096 ata_force_param_buf 4 mtd_devs 2432 mtd_dev_param 8 m68k_probes 8 isa_probes 4 arch_timers_present 4 dt_root_size_cells 4 dt_root_addr_cells 4 imx_keep_uart_clocks 4 imx_uart_clocks 4 mt8173_top_clk_data 4 mt8173_pll_clk_data 4 cpg_mode 4 cpg_mode_rates 4 cpg_mode_divs 4 cpg_mode 4 cpg_mode 4 thash_entries 4 uhash_entries 4 ic_got_reply 4 ic_first_dev 4 ic_dev 16 user_dev_name 4 ic_dhcp_msgtype 4 ic_host_name_set 4 ic_dev_mtu 4 ic_set_manually 4 ic_enable 256 vendor_class_identifier 4 ic_proto_have_if 4 dma_reserve 4 nr_kernel_pages 4 nr_all_pages 196 __clk_of_table_sentinel 200 __rmem_of_table_sentinel 196 __clksrc_of_table_sentinel 200 __iommu_of_table_sentinel 8 __cpu_method_of_table_sentinel 8 __cpuidle_method_of_table_sentinel 196 irqchip_of_match_end 32 __earlycon_table_sentinel 200 __earlycon_of_table_sentinel 6 __irf_end 26398 total
> On Oct 13, 2015, at 17:40, Arnd Bergmann <arnd@arndb.de> wrote: > > On Tuesday 13 October 2015 15:33:10 yalin wang wrote: >> >>> On Oct 13, 2015, at 04:04, Sam Ravnborg <sam@ravnborg.org> wrote: >>> >>>> --- a/include/asm-generic/vmlinux.lds.h >>>> +++ b/include/asm-generic/vmlinux.lds.h >>>> >>>> -#define BSS_SECTION(sbss_align, bss_align, stop_align) \ >>>> +#define BSS_SECTION(sbss_align, bss_align, initbss_align, stop_align) \ >>> >>> A few comments: >>> >>> 1) - please align the backslash at the end of the >>> line with the backslash above it. >>> 2) - you need to fix all the remaining users of BSS_SECTION. >>> 3) - do we really need the flexibility to specify an alignment (stop_align)? >>> If not - drop the extra argument. >>> >>> Sam >> i change lots of __initdata to __initbss to test it on ARM arch, >> > > Ok, I found my mistake in the script I used to calculate the savings, > here is the correct output showing all uninitialized variables in > multi_v7_defconfig: > > 4 done.44688 > 1024 boot_command_line > 1024 tmp_cmdline.44689 > 4 late_time_init > 4 root_mount_data > 4 root_fs_names > 4 rd_doload > 4 root_delay > 64 saved_root_name > 4 root_device_name > 4 message > 4 byte_count > 4 victim > 4 collected > 8 this_header > 4 state > 4 collect > 4 remains > 4 next_state > 8 header_buf > 8 next_header > 4 do_retain_initrd > 4 name_len > 4 body_len > 4 gid > 4 uid > 4 mtime > 4 wfd > 4 vcollected > 4 ino > 4 mode > 4 nlink > 4 major > 4 minor > 4 rdev > 4 symlink_buf > 4 name_buf > 64 msg_buf.29770 > 128 head > 4 machine_desc > 4 usermem.34390 > 4 __atags_pointer > 1024 cmd_line > 1024 default_command_line > 1536 atags_copy > 4 dma_mmu_remap_num > 64 dma_mmu_remap > 4 phys_initrd_start > 4024 phys_initrd_size > 4096 bm_pte > 4 ecc_mask > 4 initial_pmd_value > 4 arm_lowmem_limit > 24 s5p_mfc_mem > 28 tx_pad_name > 4 use_gptimer_clksrc > 4 omap_table_init > 4 mpurate > 4 am35xx_aes_hwmod_ocp_ifs > 4 am35xx_sham_hwmod_ocp_ifs > 4 dra72x_hwmod_ocp_ifs > 4 rx51_vibra_data > 4 num_special_pds > 128 special_pds > 4 main_extable_sort_needed > 4 new_log_buf_len > 24 opts.36513 > 512 smap.22469 > 512 dmap.22470 > 64 group_map.22521 > 64 group_cnt.22522 > 4 pcpu_chosen_fc > 4 vmlist > 4 vm_init_off.26867 > 4 reset_managed_pages_done > 116 boot_kmem_cache_node.32827 > 116 boot_kmem_cache.32826 > 4 dhash_entries > 4 ihash_entries > 4 mhash_entries > 4 mphash_entries > 256 nfs_root_parms > 1028 nfs_export_path > 1028 nfs_root_device > 4 gic_cnt > 4 threshold_index > 4096 ata_force_param_buf > 4 mtd_devs > 2432 mtd_dev_param > 8 m68k_probes > 8 isa_probes > 4 arch_timers_present > 4 dt_root_size_cells > 4 dt_root_addr_cells > 4 imx_keep_uart_clocks > 4 imx_uart_clocks > 4 mt8173_top_clk_data > 4 mt8173_pll_clk_data > 4 cpg_mode > 4 cpg_mode_rates > 4 cpg_mode_divs > 4 cpg_mode > 4 cpg_mode > 4 thash_entries > 4 uhash_entries > 4 ic_got_reply > 4 ic_first_dev > 4 ic_dev > 16 user_dev_name > 4 ic_dhcp_msgtype > 4 ic_host_name_set > 4 ic_dev_mtu > 4 ic_set_manually > 4 ic_enable > 256 vendor_class_identifier > 4 ic_proto_have_if > 4 dma_reserve > 4 nr_kernel_pages > 4 nr_all_pages > 196 __clk_of_table_sentinel > 200 __rmem_of_table_sentinel > 196 __clksrc_of_table_sentinel > 200 __iommu_of_table_sentinel > 8 __cpu_method_of_table_sentinel > 8 __cpuidle_method_of_table_sentinel > 196 irqchip_of_match_end > 32 __earlycon_table_sentinel > 200 __earlycon_of_table_sentinel > 6 __irf_end > > > 26398 total i am curious about your scripts , could you show me ? Thank you !
On Tuesday 13 October 2015 17:51:32 yalin wang wrote: > > 32 __earlycon_table_sentinel > > 200 __earlycon_of_table_sentinel > > 6 __irf_end > > > > > > 26398 total > i am curious about your scripts , > could you show me ? I was using some ad-hoc command line tricks, including objcopy -j .init.data build/multi_v7_defconfig/vmlinux /tmp/initdata nm initdata | sort -n | { read start b sym ; while read a b c ; do objdump -Dr --start-address=0x$start --stop-address=0x$a initdata > initdata.d/$sym ; start=$a ; sym=$c ; done } (some manual sorting to delete the files that have pre-initialized symbols) sum=0 ; nm /tmp/initdata | sort -n | { read start b sym ; while read a b c ; do test -e ../$sym && { echo $[0x$a - 0x$start]\ $sym ; sum=$[$sum + $[0x$a - 0x$start]] ; } ; start=$a ; sym=$c ; done ; echo $sum;} I'm sure there are better ways to do this, and the manual step I used at first was faulty. Arnd
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index 8b60fde..ad6d740 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -330,7 +330,7 @@ SECTIONS } #endif - BSS_SECTION(0, 0, 0) + BSS_SECTION(0, 0, 0, 0) _end = .; STABS_DEBUG diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index 8a63b4c..50b881e 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -722,6 +722,7 @@ void free_initmem(void) free_tcmmem(); poison_init_mem(__init_begin, __init_end - __init_begin); + poison_init_mem(__initbss_start, __initbss_start - __initbss_end); if (!machine_is_integrator() && !machine_is_cintegrator()) free_initmem_default(-1); } diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h index b58fd66..a63ebe9 100644 --- a/include/asm-generic/sections.h +++ b/include/asm-generic/sections.h @@ -29,6 +29,7 @@ extern char _text[], _stext[], _etext[]; extern char _data[], _sdata[], _edata[]; extern char __bss_start[], __bss_stop[]; extern char __init_begin[], __init_end[]; +extern char __initbss_start[], __initbss_end[]; extern char _sinittext[], _einittext[]; extern char _end[]; extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[]; diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index c4bd0e2..b3db62d 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -574,6 +574,14 @@ *(COMMON) \ } +#define INITBSS(initbss_align) \ + . = ALIGN(initbss_align); \ + .initbss : AT(ADDR(.initbss) - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(__initbss_start) = .; \ + *(.bss.init.data) \ + VMLINUX_SYMBOL(__initbss_end) = .; \ + } + /* * DWARF debug sections. * Symbols in the DWARF debugging sections are relative to @@ -831,10 +839,11 @@ INIT_RAM_FS \ } -#define BSS_SECTION(sbss_align, bss_align, stop_align) \ +#define BSS_SECTION(sbss_align, bss_align, initbss_align, stop_align) \ . = ALIGN(sbss_align); \ VMLINUX_SYMBOL(__bss_start) = .; \ SBSS(sbss_align) \ BSS(bss_align) \ + INITBSS(initbss_align) \ . = ALIGN(stop_align); \ VMLINUX_SYMBOL(__bss_stop) = .; diff --git a/include/linux/init.h b/include/linux/init.h index b449f37..f2960b2 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -41,6 +41,7 @@ discard it in modules) */ #define __init __section(.init.text) __cold notrace #define __initdata __section(.init.data) +#define __initbss __section(.bss.init.data) #define __initconst __constsection(.init.rodata) #define __exitdata __section(.exit.data) #define __exit_call __used __section(.exitcall.exit) diff --git a/include/linux/mm.h b/include/linux/mm.h index d30eea3..1f266f7 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -21,6 +21,7 @@ #include <linux/resource.h> #include <linux/page_ext.h> #include <linux/err.h> +#include <asm/sections.h> struct mempolicy; struct anon_vma; @@ -1722,10 +1723,11 @@ static inline void mark_page_reserved(struct page *page) */ static inline unsigned long free_initmem_default(int poison) { - extern char __init_begin[], __init_end[]; return free_reserved_area(&__init_begin, &__init_end, poison, "unused kernel"); + return free_reserved_area(&__initbss_start, &__initbss_end, + poison, "unused kernel"); } static inline unsigned long get_num_physpages(void)
This attribute can make init data to be into .initbss section, this will make the data to be NO_BITS in vmlinux, can shrink the Image file size, and speed up the boot up time. Signed-off-by: yalin wang <yalin.wang2010@gmail.com> --- arch/arm/kernel/vmlinux.lds.S | 2 +- arch/arm/mm/init.c | 1 + include/asm-generic/sections.h | 1 + include/asm-generic/vmlinux.lds.h | 11 ++++++++++- include/linux/init.h | 1 + include/linux/mm.h | 4 +++- 6 files changed, 17 insertions(+), 3 deletions(-)