MPC8349E-mITX的U-Boot连接脚本u-boot.lds分析.doc

MPC8349E-mITX的U-Boot连接脚本u-boot.lds分析转1 / MPC8349E-mITX ltib U-Boot board/mpc8349itx/u-boot.lds - by starby 2 /* 3 * Copyright (C) Freescale Semiconductor, Inc. 2006. All rights reserved. 4 * 5 * See file CREDITS for list of people who contributed to this 6 * project. 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License as10 * published by the Free Software Foundation; either version 2 of11 * the License, or (at your option) any later version.12 *13 * This program is distributed in the hope that it will be useful,14 * but WITHOUT ANY WARRANTY; without even the implied warranty of15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the16 * GNU General Public License for more details.17 *18 * You should have received a copy of the GNU General Public License19 * along with this program; if not, write to the Free Software20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,21 * MA 02111-1307 USA22 */23 24 OUTPUT_ARCH(powerpc) /* # 指定输出的可执行文件的平台为powerpc */25 SECTIONS /* 各个段的指定 */26 27 /* Read-only sections, merged into text segment: */28 . = + SIZEOF_HEADERS; /* # 地址加SIZEOF_HEADERS(0x94) .表示当前地址 */29 .interp : *(.interp) /* 定义 .interp段 : 由所有代码的.interp段共同组成. */30 .hash : *(.hash) /* .hash段: 由所有代码的.hash段共同组成. */31 .dynsym : *(.dynsym) 32 .dynstr : *(.dynstr) 33 .rel.text : *(.rel.text) 34 .rela.text : *(.rela.text) 35 .rel.data : *(.rel.data) 36 .rela.data : *(.rela.data) 37 .rel.rodata : *(.rel.rodata) 38 .rela.rodata : *(.rela.rodata) 39 .rel.got : *(.rel.got) 40 .rela.got : *(.rela.got) 41 .rel.ctors : *(.rel.ctors) 42 .rela.ctors : *(.rela.ctors) 43 .rel.dtors : *(.rel.dtors) 44 .rela.dtors : *(.rela.dtors) 45 .rel.bss : *(.rel.bss) 46 .rela.bss : *(.rela.bss) 47 .rel.plt : *(.rel.plt) 48 .rela.plt : *(.rela.plt) 49 .init : *(.init) 50 .plt : *(.plt) 51 .text : /* # 文本段 */52 53 cpu/mpc83xx/start.o (.text) /* # 文本段的第一部分start.S，后跟其他做文本段 */54 *(.text)55 *(.fixup)56 *(.got1)57 . = ALIGN(16); /* # 16字节对齐 */58 *(.rodata)59 *(.rodata1)60 *(.rodata.str1.4)61 62 .fini : *(.fini) =063 .ctors : *(.ctors) 64 .dtors : *(.dtors) 65 66 /* Read-write section, merged into data segment: */67 . = (. + 0x0FFF) & 0xFFFFF000; /* 地址对齐(地址低12位为0) */68 _erotext = .;69 PROVIDE (erotext = .);70 .reloc : /* .reloc段由以下组成 */71 72 *(.got) /* got段 */73 _GOT2_TABLE_ = .; /* _GOT2_TABLE_值为当前地址: .got段结束地址；.got2段起始地址 */74 *(.got2) /* got2段 */75 _FIXUP_TABLE_ = .; /* _FIXUP_TABLE_值: .got2段结束地址；.fixup段起始地址 */76 *(.fixup)77 78 _got2_entries = (_FIXUP_TABLE_ - _GOT2_TABLE_) 2; /* _got2_entries符号定义，其值为GOT表项个数，每个表项占4字节 */79 _fixup_entries = (. - _FIXUP_TABLE_) 2; /* _fixup_entries值为.fixup的字个数 */80 81 .data : /* # 数据段 */82 83 *(.data)84 *(.data1)85 *(.sdata)86 *(.sdata2)87 *(.dynamic)88 CONSTRUCTORS89 90 _edata = .;91 PROVIDE (edata = .);92 93 . = .;94 _u_boot_cmd_start = .; /* 定义u-boot命令起始地址，board_init_r中有调用 */95 .u_boot_cmd : *(.u_boot_cmd) /* u_boot_cmd段 */96 _u_boot_cmd_end = .; /* 同上 _u_boot_cmd_end 符号定义 */97 98 . = .;99 _start_ex_table = .;100 _ex_table : *(_ex_table) 101 _stop_ex_table = .;102 103 . = ALIGN(4096); /* 4096字节对齐 */104 _init_begin = .;105 .text.init : *(.text.init) 106 .data.init : *(.data.init) 107 . = ALIGN(4096);108 _init_end = .; /* start.S中relocate_code计算u-boot镜像text长度，利用了_init_end，后面不再搬运，直接清零clear_bss */109 110 _bss_start = .; /* bss代码段起始地址 */111 .bss :112 113 *(.sbss) *(.scommon)114 *(.dynbss)115 *(.bss)116 *(COMMON)117 118 _end = . ; /* _end 符号定义 bss代码段结束地址，u-boot镜像结束地址 */119 PROVIDE (end = .);120 /* SECTIONS 对各段定义完毕 */121 ENTRY(_start) /* # 指定可执行文件的入口点为符号_start; u-boot在链接时带 -Ttext $(TEXT_BASE) 参数，指定了lds文件中ENTRY(_start)所在的地址为TEXT_BASE*/122 123 124 /* 125 在 board/mpc8349itx/下的config.mk包含 126 #127