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# ifndef _ASM_GENERIC_SECTIONS_H_
# define _ASM_GENERIC_SECTIONS_H_
/* References to section boundaries */
vmlinux.lds: add comments for global variables and clean up useless declarations
The original goal of this patchset is to fix the bug reported by
https://bugzilla.kernel.org/show_bug.cgi?id=53501 Now it has also been
expanded to reduce common code used by memory initializion.
Patch 1-7:
1) add comments for global variables exported by vmlinux.lds
2) normalize global variables exported by vmlinux.lds
Patch 8:
Introduce helper functions mem_init_print_info() and
get_num_physpages()
Patch 9:
Avoid using global variable num_physpages at runtime
Patch 10:
Don't update num_physpages in memory_hotplug.c
Patch 11-40:
Modify arch mm initialization code to:
1) Simplify mem_init() by using mem_init_print_info()
2) Prepare for killing global variable num_physpages
Patch 41:
Kill the global variable num_physpages
With all patches applied, mem_init(), free_initmem(), free_initrd_mem()
could be as simple as below. This patch series has reduced about 1.2K
lines of code in total.
#ifndef CONFIG_DISCONTIGMEM
void __init
mem_init(void)
{
max_mapnr = max_low_pfn;
free_all_bootmem();
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
mem_init_print_info(NULL);
}
#endif /* CONFIG_DISCONTIGMEM */
void
free_initmem(void)
{
free_initmem_default(-1);
}
#ifdef CONFIG_BLK_DEV_INITRD
void
free_initrd_mem(unsigned long start, unsigned long end)
{
free_reserved_area(start, end, -1, "initrd");
}
#endif
Due to hardware resource limitations, I have only tested this on x86_64.
And the messages reported on an x86_64 system are:
Log message before applying patches:
Memory: 7745676k/8910848k available (6934k kernel code, 836024k absent, 329148k reserved, 6343k data, 1012k init)
Log message after applying patches:
Memory: 7744624K/8074824K available (6969K kernel code, 1011K data, 2828K rodata, 1016K init, 9640K bss, 330200K reserved)
Great thanks to Vineet Gupta for testing on ARC.
This patch:
Document global variables exported from vmlinux.lds.
1) Add comments about usage guidelines for global variables exported
from vmlinux.lds.S.
2) Remove unused __initdata_begin[] and __initdata_end[].
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-04 02:03:33 +04:00
/*
* Usage guidelines :
* _text , _data : architecture specific , don ' t use them in arch - independent code
* [ _stext , _etext ] : contains . text . * sections , may also contain . rodata . *
* and / or . init . * sections
* [ _sdata , _edata ] : contains . data . * sections , may also contain . rodata . *
* and / or . init . * sections .
* [ __start_rodata , __end_rodata ] : contains . rodata . * sections
* [ __init_begin , __init_end ] : contains . init . * sections , but . init . text . *
* may be out of this range on some architectures .
* [ _sinittext , _einittext ] : contains . init . text . * sections
* [ __bss_start , __bss_stop ] : contains BSS sections
*
* Following global variables are optional and may be unavailable on some
* architectures and / or kernel configurations .
* _text , _data
* __kprobes_text_start , __kprobes_text_end
* __entry_text_start , __entry_text_end
* __ctors_start , __ctors_end
*/
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extern char _text [ ] , _stext [ ] , _etext [ ] ;
extern char _data [ ] , _sdata [ ] , _edata [ ] ;
extern char __bss_start [ ] , __bss_stop [ ] ;
extern char __init_begin [ ] , __init_end [ ] ;
extern char _sinittext [ ] , _einittext [ ] ;
extern char _end [ ] ;
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extern char __per_cpu_load [ ] , __per_cpu_start [ ] , __per_cpu_end [ ] ;
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extern char __kprobes_text_start [ ] , __kprobes_text_end [ ] ;
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extern char __entry_text_start [ ] , __entry_text_end [ ] ;
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extern char __start_rodata [ ] , __end_rodata [ ] ;
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/* Start and end of .ctors section - used for constructor calls. */
extern char __ctors_start [ ] , __ctors_end [ ] ;
2008-09-04 05:43:36 +04:00
/* function descriptor handling (if any). Override
* in asm / sections . h */
# ifndef dereference_function_descriptor
# define dereference_function_descriptor(p) (p)
# endif
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/* random extra sections (if any). Override
* in asm / sections . h */
# ifndef arch_is_kernel_text
static inline int arch_is_kernel_text ( unsigned long addr )
{
return 0 ;
}
# endif
# ifndef arch_is_kernel_data
static inline int arch_is_kernel_data ( unsigned long addr )
{
return 0 ;
}
# endif
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# endif /* _ASM_GENERIC_SECTIONS_H_ */
