在外企做服务器开发， 目前是项目经理， 管理两个server开发的项目。不做嵌入式好久了。
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分类： LINUX
2009-06-17 15:54:29
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ld的中文手册：
这里还有一本书 还不错介绍ELF。
用 xx-objdump 来查看 binary的信息，尤其是调试信息
以下都是 vmlinux 和 head.o为例的。
1，看起来， 每个版本的objdump的支持都不一样的。
至少输出的选项也是不一样的。
当然最有用就是：
-D : 反汇编所有的sections
-d : 反汇编executable sections
-S : 混合显示汇编代码和原始代码， 太有用了 ******
-t : 显示调试信息，尤其是可以显示出行号和文件名和路径（配合-l）
-l, --line-numbers Include line numbers and filenames in output
下面就是endian的选择了
-EB --endian=big Assume big endian format when disassembling
-EL --endian=little Assume little endian format when disassembling
下面输出的 elf32-tradbigmips是支持的平台
[bob@localhost linux-2.6.20.9]$ /home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-objdump
-b
/home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-objdump: option requires an argument --
b
Usage: /home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-objdump
Display information from object
At least one of the following switches must be given:
-a, --archive-headers Display archive header information
-f, --file-headers Display the contents of the overall file header
-p, --private-headers Display object format specific file header contents
-h, --[section-]headers Display the contents of the section headers
-x, --all-headers Display the contents of all headers
-d, --disassemble Display assembler contents of executable sections
-D, --disassemble-all Display assembler contents of all sections
-S, --source Intermix source code with disassembly
-s, --full-contents Display the full contents of all sections requested
-g, --debugging Display debug information in object file
-G, --stabs Display (in raw form) any STABS info in the file
-t, --syms Display the contents of the symbol table(s)
-T, --dynamic-syms Display the contents of the dynamic symbol table
-r, --reloc Display the relocation entries in the file
-R, --dynamic-reloc Display the dynamic relocation entries in the file
-v, --version Display this program's version number
-i, --info List object formats and architectures supported
-H, --help Display this information
The following switches are optional:
-b, --target=BFDNAME Specify the target object format as BFDNAME
-m, --architecture=MACHINE Specify the target architecture as MACHINE
-j, --section=NAME Only display information for section NAME
-M, --disassembler-options=OPT Pass text OPT on to the disassembler
-EB --endian=big Assume big endian format when disassembling
-EL --endian=little Assume little endian format when disassembling
--file-start-context Include context from start of file (with -S)
-l, --line-numbers Include line numbers and filenames in output
-C, --demangle[=STYLE] Decode mangled/processed symbol names
The STYLE, if specified, can be `auto', 'gnu',
'lucid', 'arm', 'hp', 'edg', or 'gnu-new-abi'
-w, --wide Format output for more than 80 columns
-z, --disassemble-zeroes Do not skip blocks of zeroes when disassembling
--start-address=ADDR Only process data whoes address is >= ADDR
--stop-address=ADDR Only process data whoes address is <= ADDR
--prefix-addresses Print complete address alongside disassembly
--[no-]show-raw-insn Display hex alongside symbolic disassembly
--adjust-vma=OFFSET Add OFFSET to all displayed section addresses
/home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-objdump: supported targets: elf32-
tradbigmips elf32-tradlittlemips elf64-tradbigmips elf64-tradlittlemips ecoff-bigmips ecoff-
littlemips elf64-little elf64-big elf32-little elf32-big srec symbolsrec tekhex binary ihex
/home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-objdump: supported architectures: mips
mips:3000 mips:3900 mips:4000 mips:4010 mips:4100 mips:4111 mips:4300 mips:4400 mips:4600 mips:4650
mips:5000 mips:6000 mips:8000 mips:10000 mips:12000 mips:16 mips:mips5 mips:isa32 mips:isa64
mips:sb1
2，用法：比如
#mips-linux-objdump -D -l -t -x -S arch/mips/kernel/head.o
可以看到类似：
/home/work/data3/standby/dv_kernel_suspend2/linux/arch/mips/kernel/head.S:245
li t1, 0xFFFFFFF8 这个上面文件的245 line
44: 3c09ffff lui t1,0xffff
48: 3529fff8 ori t1,t1,0xfff8 这两个是反汇编后的指令
这样我们可以很轻松的看出 li t1, 0xFFFFFFF8 在汇编后，实际上是两条指令。
还有对应的行号和文件路径
其实这样，我我们就可以知道 代码实际上是如何执行的。
3，readelf 也可以显示 symbol信息：
/home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-readelf -s arch/mips/kernel/head.o
4， readelf -h 最有用的就是可以显示 kernel的入口点了。
[bob@localhost linux]$ /home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-readelf -h vmlinux
ELF Header:
Magic: 7f 45 4c 46 01 02 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, big endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: MIPS R3000
Version: 0x1
Entry point address: 0x8025e040
Start of program headers: 52 (bytes into file)
Start of section headers: 31477732 (bytes into file)
Flags: 0x10001001, noreorder, o32, mips2
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 3
Size of section headers: 40 (bytes)
Number of section headers: 31
Section header string table index: 28
5，xx-ld –M 非常有用，可以到很多重要的信息
Xx-ld 可以跟其他的选项， man ld
Ld的中文手册： s
比如 编译kernel，最后的连接的过程：
/home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-ld -G 0 -static -T arch/mips/ld.script arch/mips/kernel/head.o arch/mips/kernel/init_task.o init/main.o init/version.o init/do_mounts.o --start-group arch/mips/kernel/kernel.o arch/mips/mm/mm.o kernel/kernel.o mm/mm.o fs/fs.o ipc/ipc.o arch/mips/math-emu/fpu_emulator.o arch/mips/emma2_se/emma2.o drivers/char/char.o drivers/block/block.o drivers/misc/misc.o drivers/net/net.o drivers/ide/idedriver.o drivers/pci/driver.o drivers/mtd/mtdlink.o drivers/net/wireless/wireless_net.o drivers/usb/usbdrv.o drivers/media/media.o drivers/md/mddev.o net/network.o arch/mips/lib/lib.a /home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a --end-group -o vmlinux –M
你可以在后面加一个 –M 参数。
`-M'
`--print-map'
打印一个连接位图到标准输出.一个连接位图提供的关于连接的信息有如下一些:
* 目标文件和符号被映射到内存的哪些地方.
* 普通符号如何被分配空间.
* 所有被连接进来的档案文件,还有导致档案文件被包含进来的那个符号.
非常之详细。
比如：
.text.init 0x000000008025e000 0xb0 arch/mips/kernel/head.o
0x000000008025e000 except_vec2_generic
0x000000008025e038 except_vec_nmi
0x000000008025e040 kernel_entry
0x000000008025e028 except_vec4
0x000000008025e030 except_vec_ejtag_debug
.text.init 0x000000008025e0b0 0x758 init/main.o
0x000000008025e1a4 calibrate_delay
0x000000008025e564 start_kernel
。。。。
显示由谁连接来的。
LOAD arch/mips/kernel/head.o
LOAD arch/mips/kernel/init_task.o
LOAD init/main.o
LOAD init/version.o
LOAD init/do_mounts.o
START GROUP
LOAD arch/mips/kernel/kernel.o
LOAD arch/mips/mm/mm.o
LOAD kernel/kernel.o
LOAD mm/mm.o
LOAD fs/fs.o
LOAD ipc/ipc.o
LOAD arch/mips/math-emu/fpu_emulator.o
LOAD arch/mips/emma2_se/emma2.o
LOAD drivers/char/char.o
LOAD drivers/block/block.o
LOAD drivers/misc/misc.o
LOAD drivers/net/net.o
LOAD drivers/ide/idedriver.o
LOAD drivers/pci/driver.o
LOAD drivers/mtd/mtdlink.o
LOAD drivers/net/wireless/wireless_net.o
LOAD drivers/usb/usbdrv.o
LOAD drivers/media/media.o
LOAD drivers/md/mddev.o
LOAD net/network.o
LOAD arch/mips/lib/lib.a
LOAD /home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a
END GROUP
OUTPUT(vmlinux elf32-tradbigmips)
还可以看出 一些段上的详细内容， 不过，一些 东西，我也不知道：
。。。
.debug_line 0x0000000000000000 0x3b913a
.debug_line 0x0000000000000000 0x93 arch/mips/kernel/head.o
.debug_line 0x0000000000000093 0x299d arch/mips/kernel/init_task.o
.debug_line 0x0000000000002a30 0x313e init/main.o
.debug_line 0x0000000000005b6e 0x79 init/version.o
.debug_line 0x0000000000005be7 0x39cd init/do_mounts.o
.debug_line 0x00000000000095b4 0x32291 arch/mips/kernel/kernel.o
。。。
其他的选项：
`-s'
`--strip-all'
忽略输出文件中所有的符号信息.
`-S'
`--strip-debug'
忽略输出文件中所有的调试符号信息(但不是所有符号).
`-t'
`--trace'
打印'ld'处理的所有输入文件的名字.
命令例子1：-y function_name :可以显示哪些.o 调用这个function
#mips-linux/bin/mips-linux-ld -G 0 -static -T arch/mips/ld.script arch/mips/kernel/head.o arch/mips/kernel/init_task.o init/main.o init/version.o init/do_mounts.o --start-group arch/mips/kernel/kernel.o arch/mips/mm/mm.o kernel/kernel.o mm/mm.o fs/fs.o ipc/ipc.o arch/mips/math-emu/fpu_emulator.o arch/mips/emma2_se/emma2.o drivers/char/char.o drivers/block/block.o drivers/misc/misc.o drivers/net/net.o drivers/ide/idedriver.o drivers/pci/driver.o drivers/mtd/mtdlink.o drivers/net/wireless/wireless_net.o drivers/usb/usbdrv.o drivers/media/media.o drivers/md/mddev.o net/network.o arch/mips/lib/lib.a /home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a --end-group -o vmlinux -y printk
===输出=== 可以看出 都有那些文件调用了printk ，不过好像不全
init/main.o: reference to printk
init/do_mounts.o: reference to printk
arch/mips/kernel/kernel.o: reference to printk
arch/mips/mm/mm.o: reference to printk
kernel/kernel.o: definition of printk
mm/mm.o: reference to printk
fs/fs.o: reference to printk
ipc/ipc.o: reference to printk
arch/mips/math-emu/fpu_emulator.o: reference to printk
arch/mips/emma2_se/emma2.o: reference to printk
drivers/char/char.o: reference to printk
drivers/block/block.o: reference to printk
drivers/net/net.o: reference to printk
drivers/ide/idedriver.o: reference to printk
drivers/pci/driver.o: reference to printk
drivers/mtd/mtdlink.o: reference to printk
drivers/usb/usbdrv.o: reference to printk
drivers/media/media.o: reference to printk
net/network.o: reference to printk
arch/mips/lib/lib.a(rtc-no.o): reference to printk
arch/mips/lib/lib.a(dump_tlb.o): reference to printk
/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a(dump_stack.o): reference to printk
命令例子2：你可以加 –t选项，知道哪些文件构成了vmlinux.
[bob@localhost linux]$ /home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-ld -G 0 -static -T arch/mips/ld.script arch/mips/kernel/head.o arch/mips/kernel/init_task.o init/main.o init/version.o init/do_mounts.o --start-group arch/mips/kernel/kernel.o arch/mips/mm/mm.o kernel/kernel.o mm/mm.o fs/fs.o ipc/ipc.o arch/mips/math-emu/fpu_emulator.o arch/mips/emma2_se/emma2.o drivers/char/char.o drivers/block/block.o drivers/misc/misc.o drivers/net/net.o drivers/ide/idedriver.o drivers/pci/driver.o drivers/mtd/mtdlink.o drivers/net/wireless/wireless_net.o drivers/usb/usbdrv.o drivers/media/media.o drivers/md/mddev.o net/network.o arch/mips/lib/lib.a /home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a --end-group -o vmlinux -t
======命令输出=========
/home/bob/gcc-3.2.2-uClibc-0.9.19/mips-linux/bin/mips-linux-ld: mode elf32btsmip
arch/mips/kernel/head.o
arch/mips/kernel/init_task.o
init/main.o
init/version.o
init/do_mounts.o
arch/mips/kernel/kernel.o
arch/mips/mm/mm.o
kernel/kernel.o
mm/mm.o
fs/fs.o
ipc/ipc.o
arch/mips/math-emu/fpu_emulator.o
arch/mips/emma2_se/emma2.o
drivers/char/char.o
drivers/block/block.o
drivers/net/net.o
drivers/ide/idedriver.o
drivers/pci/driver.o
drivers/mtd/mtdlink.o
drivers/usb/usbdrv.o
drivers/media/media.o
net/network.o
(arch/mips/lib/lib.a)csum_partial.o
(arch/mips/lib/lib.a)csum_partial_copy.o
(arch/mips/lib/lib.a)rtc-no.o
(arch/mips/lib/lib.a)memcpy.o
(arch/mips/lib/lib.a)memset.o
(arch/mips/lib/lib.a)strlen_user.o
(arch/mips/lib/lib.a)strncpy_user.o
(arch/mips/lib/lib.a)strnlen_user.o
(arch/mips/lib/lib.a)dump_tlb.o
(arch/mips/lib/lib.a)ide-no.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)errno.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)ctype.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)string.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)vsprintf.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)cmdline.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)rbtree.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)dump_stack.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)rwsem-spinlock.o
(/home/work/data3/standby/dv_kernel_suspend2/linux/lib/lib.a)zlib_inflate.o
