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authorJiang Liu <liuj97@gmail.com>2013-07-03 15:03:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 16:07:34 -0700
commit1622d1abdf7b554eb7cc40c0d08d989176732242 (patch)
treed0553ae064f5ef452c1b34a1ef112279791d8bce
parente6c495a96ce02574e765d5140039a64c8d4e8c9e (diff)
downloadlinux-1622d1abdf7b554eb7cc40c0d08d989176732242.tar.bz2
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>
-rw-r--r--include/asm-generic/sections.h21
1 files changed, 20 insertions, 1 deletions
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index c1a1216e29ce..f1a24b5c3b90 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -3,6 +3,26 @@
/* References to section boundaries */
+/*
+ * 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
+ */
extern char _text[], _stext[], _etext[];
extern char _data[], _sdata[], _edata[];
extern char __bss_start[], __bss_stop[];
@@ -12,7 +32,6 @@ extern char _end[];
extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[];
extern char __kprobes_text_start[], __kprobes_text_end[];
extern char __entry_text_start[], __entry_text_end[];
-extern char __initdata_begin[], __initdata_end[];
extern char __start_rodata[], __end_rodata[];
/* Start and end of .ctors section - used for constructor calls. */