{"id":1525,"date":"2015-03-04T16:07:44","date_gmt":"2015-03-04T08:07:44","guid":{"rendered":"http:\/\/www.51cos.com\/?p=1525"},"modified":"2015-03-04T16:07:44","modified_gmt":"2015-03-04T08:07:44","slug":"%e5%88%86%e6%9e%90uboot%e6%98%af%e5%a6%82%e4%bd%95%e5%90%af%e5%8a%a8%e5%86%85%e6%a0%b8%e7%9a%84%e5%88%86%e6%9e%90busybox%e4%b8%adinit%e7%a8%8b%e5%ba%8f%e7%9a%84%e8%bf%90%e8%a1%8c%e8%bf%87%e7%a8%8b","status":"publish","type":"post","link":"http:\/\/www.51cos.com\/?p=1525","title":{"rendered":"\u5206\u6790uboot\u662f\u5982\u4f55\u542f\u52a8\u5185\u6838\u7684\/\u5206\u6790busybox\u4e2dinit\u7a0b\u5e8f\u7684\u8fd0\u884c\u8fc7\u7a0b"},"content":{"rendered":"
\n
\n

\n<\/strong><\/div>\n<\/blockquote>\n<\/div>\n
1.uboot\u542f\u52a8\u5185\u6838\u7684\u4ee3\u7801\u7f29\u51cf\u5982\u4e0b\uff1a
\ns = getenv (“bootcmd”);
\ndebug (“### main_loop: bootcmd=\\”%s\\”\\n”, s ? s : “<UNDEFINED>”);
\nif (bootdelay >= 0 && s && !abortboot (bootdelay))
\n{
\nrun_command (s, 0);
\n}<\/p>\n

2.\u5047\u8bbebootcmd = nand read.jffs2 0x30007FC0 kernel; bootm 0x30007FC0
\n<1> nand read.jffs2 0x30007FC0 kernel
\nnand read.jffs2 0x30007FC0 kernel;
\n\u4ecenand\u8bfb\u51fa\u5185\u6838\uff1a\u4ece\u54ea\u91cc\u8bfb\uff1f\u00a0\u00a0 \u4ecekernel\u5206\u533a
\n\u653e\u5230\u54ea\u91cc\u53bb\uff1f-0x30007FC0<\/p>\n

\u4e0b\u9762\u8bb2\u89e3\u4ec0\u4e48\u662f\u5206\u533a\uff1a
\n\u5c31\u662f\u5c06nand\u5212\u5206\u4e3a\u51e0\u4e2a\u533a\u57df\uff0c\u4e00\u822c\u5982\u4e0b\uff1a
\nbootloader-\u300bparams-\u300bkernel-\u300broot<\/p>\n

\u8fd9\u4e9b\u5206\u533a\u7684\u5212\u5206\u662f\u5728\/include\/configs\/mini2440.h\u4e2d\u5199\u6b7b\u7684\uff1a
\n#define MTDPARTS_DEFAULT “mtdparts=nandflash0:250k@0(bootloader),” \\
\n“128k(params),” \\
\n“5m(kernel),” \\
\n“-(root)”
\n\u6ce8:@0\u8868\u793a\u4ece0\u5730\u5740\u5f00\u59cb\uff0c250k\u7684bootloader\u5206\u533a\u53ef\u80fd\u5bf9\u67d0\u4e9buboot\u4e0d\u591f\u7528\uff0c\u8fd9\u91cc\u53ea\u662f\u4e3e\u4f8b\u800c\u5df2\u3002
\n\u5c06\u4e0a\u9762\u7684\u4fe1\u606f\u6362\u7b97\u6210\u5341\u516d\u8fdb\u5236\uff1a
\n#\u00a0\u00a0\u00a0\u00a0name\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u5927\u5c0f\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u5728nand\u4e0a\u7684\u8d77\u59cb\u5730\u5740
\n0\u00a0\u00a0\u00a0\u00a0bootloader\u00a0\u00a0\u00a0\u00a0 0x00040000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a00x00000000
\n1\u00a0\u00a0\u00a0\u00a0params\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a00x00020000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a00x00040000
\n2\u00a0\u00a0\u00a0\u00a0kernel\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a00x00200000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a00x00060000
\n3\u00a0\u00a0\u00a0\u00a0root\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a00xfda00000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a00x00260000<\/p>\n

\u90a3\u4e48\u4e0a\u9762\u7684nand read.jffs2 0x30007FC0 kernel\u5c31\u7b49\u4ef7\u4e8e\uff1a
\nnand read.jffs2 0x30007FC0 0x00060000 0x00200000
\n\u6ce8\uff1a\u8fd9\u91cc\u7684read.jffs2\u5e76\u4e0d\u662f\u6307\u5b9a\u8981\u4ec0\u4e48\u7279\u5b9a\u7684\u683c\u5f0f\uff0c\u800c\u662f\u7528read.jffs2\u4e0d\u9700\u8981\u5757\/\u9875\u5bf9\u9f50,\u6240\u4ee5\u8fd9\u4e2akernel\u7684\u5206\u533a\u5927\u5c0f\u53ef\u4ee5
\n\u968f\u610f\u5b9a\u3002<\/p>\n

<2> bootm 0x30007FC0
\n\u5173\u952e\u51fd\u6570do_bootm()<\/p>\n

flash\u4e0a\u5b58\u7684\u5185\u6838\uff1auImage
\nuImage = \u5934\u90e8+\u771f\u6b63\u7684\u5185\u6838<\/p>\n

\u5934\u90e8\u7684\u5b9a\u4e49\u5982\u4e0b\uff1a
\ntypedef struct image_header {
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_magic;\u00a0\u00a0\u00a0\u00a0\/* Image Header Magic Number\u00a0\u00a0\u00a0\u00a0*\/
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_hcrc;\u00a0\u00a0\u00a0\u00a0\/* Image Header CRC Checksum\u00a0\u00a0\u00a0\u00a0*\/
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_time;\u00a0\u00a0\u00a0\u00a0\/* Image Creation Timestamp\u00a0\u00a0\u00a0\u00a0*\/
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_size;\u00a0\u00a0\u00a0\u00a0\/* Image Data Size\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_load;\u00a0\u00a0\u00a0\u00a0\/* Data\u00a0\u00a0\u00a0\u00a0 Load\u00a0\u00a0Address\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_ep;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/* Entry Point Address\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_dcrc;\u00a0\u00a0\u00a0\u00a0\/* Image Data CRC Checksum\u00a0\u00a0\u00a0\u00a0*\/
\nuint8_t\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0ih_os;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/* Operating System\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nuint8_t\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0ih_arch;\u00a0\u00a0\u00a0\u00a0\/* CPU architecture\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nuint8_t\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0ih_type;\u00a0\u00a0\u00a0\u00a0\/* Image Type\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nuint8_t\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0ih_comp;\u00a0\u00a0\u00a0\u00a0\/* Compression Type\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nuint8_t\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0ih_name[IH_NMLEN];\u00a0\u00a0\u00a0\u00a0\/* Image Name\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\n} image_header_t;
\n\u6211\u4eec\u9700\u8981\u5173\u5fc3\u7684\u662f\uff1a
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_load;\u00a0\u00a0\u00a0\u00a0\/* Data\u00a0\u00a0\u00a0\u00a0 Load\u00a0\u00a0Address\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nuint32_t\u00a0\u00a0\u00a0\u00a0ih_ep;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/* Entry Point Address\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0*\/
\nih_load\u662f\u52a0\u8f7d\u5730\u5740\uff0c\u5373\u5185\u6838\u8fd0\u884c\u662f\u5e94\u8be5\u4f4d\u4e8e\u7684\u5730\u65b9
\nih_ep\u662f\u5165\u53e3\u5730\u5740\uff0c\u5373\u5185\u6838\u7684\u5165\u53e3\u5730\u5740<\/p>\n

\u8fd9\u4e0euboot\u662f\u7c7b\u4f3c\u7684\uff0cuboot\u7684\u52a0\u8f7d\u5730\u5740\u662fTEXT_BASE = 0x33F80000\uff1b\u5165\u53e3\u5730\u5740\u662fstart.S\u4e2d\u7684_start\u3002<\/p>\n

\u5176\u5b9e\u6211\u4eec\u628a\u5185\u6838\u4e2dnand\u8bfb\u51fa\u6765\u7684\u65f6\u5019\u662f\u53ef\u4ee5\u653e\u5728\u5185\u6838\u7684\u4efb\u4f55\u5730\u65b9\u7684\uff0c\u59820x31000000\uff0c0x32000000\u7b49\u7b49\uff0c\u53ea\u8981\u5b83\u4e0d\u7834\u574fuboot\u6240\u5360\u7528\u7684\u5185\u5b58\u7a7a\u95f4\u5c31\u53ef\u4ee5\u4e86\uff0c\u5982\u4e0b\u56fe\uff1a
\n\u4ece0x33F4DF74-0x30000000\u90fd\u662f\u53ef\u4ee5\u7528\u7684\u3002<\/p>\n

\u90a3\u4e48\u4e3a\u4ec0\u4e48\u65e2\u7136\u8bbe\u5b9a\u597d\u4e86\u52a0\u8f7d\u5730\u5740\u548c\u5165\u53e3\u5730\u5740\u5185\u6838\u8fd8\u80fd\u968f\u610f\u653e\u5462\uff1f
\n\u90a3\u662f\u56e0\u4e3auImage\u6709\u4e00\u4e2a\u5934\u90e8\uff01\u5934\u90e8\u91cc\u6709\u52a0\u8f7d\u5730\u5740\u548c\u5165\u53e3\u5730\u5740\uff0c\u5f53\u6211\u4eec\u7528bootm xxx\u7684\u65f6\u5019\uff0c
\ndo_bootm\u8fd9\u4e2a\u51fd\u6570\u4f1a\u5148\u53bb\u8bfbuImage\u7684\u5934\u90e8\u4ee5\u83b7\u53d6\u8be5uImage\u7684\u52a0\u8f7d\u5730\u5740\u548c\u5165\u53e3\u5730\u5740\uff0c\u5f53\u53d1\u73b0\u8be5uImage\u76ee\u524d\u6240\u5904\u7684\u5185\u5b58\u5730\u5740\u4e0d\u7b49\u4e8e\u5b83\u7684\u52a0\u8f7d\u5730\u5740\u65f6\uff0c\u8be5\u51fd\u6570\u4f1a\u5c06\u8be5uImage\u79fb\u52a8\u5230\u5b83\u7684\u52a0\u8f7d\u5730\u5740\u4e0a\uff0c\u5728\u4ee3\u7801\u4e2d\u4f53\u73b0\u5982\u4e0b\uff1a
\ncase IH_COMP_NONE:\uff1a
\nif (load != image_start)
\n{
\nmemmove_wd ((void *)load, (void *)image_start, image_len, CHUNKSZ);
\n}
\n\u53e6\u5916\uff0c\u5f53\u6211\u4eec\u7684\u5185\u6838\u6b63\u597d\u5904\u4e8e\u5934\u90e8\u6307\u5b9a\u7684\u52a0\u8f7d\u5730\u5740\u7684\u8bdd\uff0c\u90a3\u4e48\u5c31\u4e0d\u7528uboot\u7684do_bootm\u51fd\u6570\u6765\u5e2e\u6211\u4eec\u642c\u8fd0\u5185\u6838\u4e86\uff0c\u8fd9\u6837\u53ef\u4ee5\u8282\u7701\u542f\u52a8\u65f6\u95f4\u3002\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u6211\u4eec\u4e00\u822c\u90fd\u4e0b\u8f7duImage\u5230
\n0x30007FC0\u7684\u539f\u56e0\u4e86\uff01<\/p>\n

\u6211\u4eec\u6240\u7528\u7684\u5185\u6838\u52a0\u8f7d\u5730\u5740\u662f0x30008000\uff0c\u800c\u5934\u90e8\u7684\u5927\u5c0f\u4e3a64\u4e2a\u5b57\u8282\uff0c\u6240\u4ee5\u5c06\u5185\u6838\u62f7\u8d1d\u52300x30007FC0\u65f6\uff0c\u518d\u52a0\u8f7d\u5934\u90e8\u768464\u4e2a\u5b57\u8282\uff0c\u5185\u6838\u6b63\u597d\u4f4d\u4e8e0x30008000\u5904\uff01<\/p>\n

\u73b0\u5728\u603b\u7ed3bootm\u505a\u4e86\u4ec0\u4e48\uff1a
\n1.\u00a0\u00a0\u00a0\u00a0\u8bfb\u53d6\u5934\u90e8
\n2.\u00a0\u00a0\u00a0\u00a0\u5c06\u5185\u6838\u79fb\u52a8\u5230\u52a0\u8f7d\u5730\u5740
\n3.\u00a0\u00a0\u00a0\u00a0\u542f\u52a8\u5185\u6838<\/p>\n

\u5177\u4f53\u5982\u4f55\u542f\u52a8\u5185\u6838\uff1f
\n\u4f7f\u7528do_bootm_linux()\uff0c\u5728\/lib_arm\/bootm.c\u5b9a\u4e49\uff0c\u56e0\u4e3a\u6211\u4eec\u5df2\u7ecf\u77e5\u9053\u5165\u53e3\u5730\u5740\u4e86\uff0c\u6240\u4ee5\u53ea\u9700\u8df3\u5230\u5165\u53e3\u5730\u5740\u5c31\u53ef\u4ee5\u542f\u52a8linux\u5185\u6838\u4e86\uff0c\u4f46\u662f\u5728\u8fd9\u4e4b\u524d\u9700\u8981\u505a\u4e00\u4ef6\u4e8b\u2014\u2014\u2014\u2014uboot\u4f20\u9012\u53c2\u6570\u7ed9\u5185\u6838\uff01\uff01
\n\u73b0\u5728\u6765\u5206\u6790do_bootm_linux()\u8fd9\u4e2a\u51fd\u6570\uff1a
\ntheKernel = (void (*)(int, int, uint))images->ep;\/\/\u5148\u662f\u5c06\u5165\u53e3\u5730\u5740\u8d4b\u503c\u7ed9theKernel
\ntheKernel (0, machid, bd->bi_boot_params);\/\/\u7136\u540e\u662f\u8c03\u7528thekernel
\n\u51fd\u6570\uff0c\u4ee50\uff0cmachid\uff0cbd->bi_boot_params\u4f5c\u4e3a\u53c2\u6570
\n\u4e0b\u9762\u5206\u6790\u8fd9\u4e09\u4e2a\u53c2\u6570\uff1a
\n1.machid\u5c31\u662fuboot\u91cc\u8bbe\u7f6e\u597d\u7684\u677f\u5b50\u7684\u673a\u5668\u7801\uff0cmini2440\u7684\u662fMACH_TYPE_MINI2440 (1999),\u5185\u6838\u6240\u8bbe\u7f6e\u7684\u673a\u5668\u7801\u548cuboot\u6240\u8bbe\u7f6e\u7684\u673a\u5668\u7801\u5fc5\u987b\u4e00\u81f4\u624d\u80fd\u542f\u52a8\u5185\u6838
\n2.bd->bi_boot_parmas\u5c31\u662fuboot\u9700\u4f20\u9012\u7ed9\u5185\u6838\u7684\u542f\u52a8\u53c2\u6570\u6240\u4f4d\u4e8e\u7684\u5730\u5740
\n3.0\u6682\u65f6\u8fd8\u4e0d\u77e5\u9053\u4ec0\u4e48\u4f5c\u7528\/**********************************************\/<\/p>\n

\u90a3\u4e48uboot\u4f20\u7ed9\u5185\u6838\u7684\u542f\u52a8\u53c2\u6570\u662f\u5728\u54ea\u91cc\u8bbe\u7f6e\u7684\u5462\uff1f
\n\u5176\u5b9e\u5c31\u662f\u5728\u8c03\u7528\u00a0\u00a0\u00a0\u00a0theKernel (0, machid, bd->bi_boot_params);\u524d\u9762\u7684\u4e00\u5c0f\u6bb5\u4ee3\u7801\u91cc\u8bbe\u7f6e\u7684\uff0c\u4e0b\u9762\u6211\u622a\u53d6\u4e86\u90e8\u5206\u7247\u6bb5\uff1a
\nsetup_start_tag (bd);
\nsetup_revision_tag (&params);
\nsetup_memory_tags (bd);
\nsetup_commandline_tag (bd, commandline);
\nsetup_initrd_tag (bd, images->rd_start, images->rd_end);
\nsetup_videolfb_tag ((gd_t *) gd);
\nsetup_end_tag (bd);
\n\u6bcf\u4e00\u4e2a\u542f\u52a8\u53c2\u6570\u5bf9\u5e94\u4e00\u4e2atag\u7ed3\u6784\u4f53\uff0c\u6240\u8c13\u7684\u8bbe\u7f6e\u4f20\u9012\u53c2\u6570\u5176\u5b9e\u5c31\u662f\u521d\u59cb\u5316\u8fd9\u4e9btag\u7684\u503c\uff0c\u60f3\u4e86\u89e3\u8fd9\u4e2a\u7ed3\u6784\u4f53\u4ee5\u53ca\u8fd9\u4e9btag\u7684\u503c\u662f\u5982\u4f55\u8bbe\u7f6e\u7684\u8bf7\u770b\u97e6\u4e1c\u5c71\u7684\u4e66\u5173\u4e8euboot\u79fb\u690d\u7ae0\u8282\uff01
\n\u4e0b\u9762\u6211\u4eec\u770b\u4e00\u4e0bsetup_start_tag(bd)\u8fd9\u4e2a\u51fd\u6570\u5148\uff1a
\nstatic void setup_start_tag (bd_t *bd)
\n{
\nparams = (struct tag *) bd->bi_boot_params;
\n\/\/\u5728board.c\u4e2d\u6709\u4e00\u53e5gd->bd->bi_boot_params = 0x30000100\uff0c\u8fd9\u91cc\u8bbe\u7f6e\u4e86\u53c2\u6570\u5b58\u653e\u7684\u4f4d\u7f6e<\/p>\n

params->hdr.tag = ATAG_CORE;
\nparams->hdr.size = tag_size (tag_core);<\/p>\n

params->u.core.flags = 0;
\nparams->u.core.pagesize = 0;
\nparams->u.core.rootdev = 0;<\/p>\n

params = tag_next (params);
\n}
\n\u6211\u4eec\u518d\u6765\u770b\u4e0bsetup_commandline_tag (bd, commandline);\u8fd9\u4e2a\u51fd\u6570\uff1a
\nstatic void setup_commandline_tag (bd_t *bd, char *commandline)
\n{
\n\/\/ commandline\u5c31\u662f\u6211\u4eec\u7684bootargs
\nchar *p;
\nif (!commandline)
\nreturn;
\nfor (p = commandline; *p == ‘ ‘; p++);
\nif (*p == ‘\\0’)
\nreturn;
\nparams->hdr.tag = ATAG_CMDLINE;
\nparams->hdr.size =
\n(sizeof (struct tag_header) + strlen (p) + 1 + 4) >> 2;
\nstrcpy (params->u.cmdline.cmdline, p);
\nparams = tag_next (params);
\n}
\nLinux\u5185\u6838\u542f\u52a8\u65f6\u5c31\u4f1a\u53bb\u8bfb\u53d6\u8fd9\u4e9btag\u53c2\u6570<\/strong><\/div>\n

<\/div>\n
<\/div>\n
<\/div>\n
——————————————<\/div>\n
<\/div>\n
<\/div>\n
\u79fb\u690duboot\u7684\u76ee\u7684\u662f\u542f\u52a8\u5185\u6838\uff0c\u542f\u52a8\u5185\u6838\u7684\u76ee\u7684\u662f\u8fd0\u884c\u5e94\u7528\u7a0b\u5e8f\uff0c\u4ece\u5185\u6838\u7684\u542f\u52a8\u6d41\u7a0b\u4e2d\u53ef\u4ee5\u77e5\u9053\u5185\u6838\u542f\u52a8\u7684\u7b2c\u4e00\u4e2a\u5e94\u7528\u7a0b\u5e8f\u5c31\u662fbusybox\u91cc\u7684\/sbin\/init\u8fdb\u7a0b\uff01<\/p>\n

\u4f46\u662f\u6211\u4eec\u7684\u6700\u7ec8\u76ee\u7684\u4e0d\u662f\u542f\u52a8init\u8fdb\u7a0b\uff0c\u800c\u662f\u8fd0\u884c\u5ba2\u6237\u7684\u7a0b\u5e8f\uff01
\n\u90a3\u4e48init\u8fdb\u7a0b\u662f\u5982\u4f55\u9009\u62e9\u6027\u7684\u8fd0\u884c\u5ba2\u6237\u7684\u7a0b\u5e8f\u5462\uff1f\u6211\u4eec\u731c\u6d4binit\u8fdb\u7a0b\u80af\u5b9a\u9700\u8981\uff1a
\n\uff081\uff09 \u8bfb\u53d6\u4e00\u4e2a\u914d\u7f6e\u6587\u4ef6
\n\uff082\uff09 \u89e3\u6790\u8be5\u914d\u7f6e\u6587\u4ef6
\n\uff083\uff09 \u6839\u636e\u914d\u7f6e\u6587\u4ef6\u6267\u884c\u5ba2\u6237\u7684\u7a0b\u5e8f<\/p>\n

\u4e0b\u9762\u6211\u4eec\u6765\u9605\u8bfbbusybox\u4e2dinit\u7a0b\u5e8f\u7684\u6e90\u7801\uff0c\u5728init.c\u4e2d\u7684init_main\uff08\uff09\u4e2d\uff1a
\n1.\u9996\u5148\u662f\u8bbe\u7f6e\u4fe1\u53f7<\/strong>
\nsignal(SIGHUP, exec_signal);
\nsignal(SIGQUIT, exec_signal);
\nsignal(SIGUSR1, shutdown_signal);
\nsignal(SIGUSR2, shutdown_signal);
\nsignal(SIGINT, ctrlaltdel_signal);
\nsignal(SIGTERM, shutdown_signal);
\nsignal(SIGCONT, cont_handler);
\nsignal(SIGSTOP, stop_handler);
\nsignal(SIGTSTP, stop_handler);
\n2.\u521d\u59cb\u5316\/dev\/console<\/strong>
\nconsole_init();
\n3.\u89e3\u6790\u914d\u7f6e\u6587\u4ef6<\/strong>
\nif (argc > 1
\n&& (!strcmp(argv[1], “single”) || !strcmp(argv[1], “-s”) || LONE_CHAR(argv[1], ‘1’))
\n) {
\n} else {
\nparse_inittab();
\n}
\n\u5185\u6838\u542f\u52a8\/sbin\/init\u662f\u6ca1\u6709\u4f20\u5982\u4f55\u53c2\u6570\uff0c\u6240\u4ee5\u8fdb\u5165parse_inittab\uff08\uff09\u51fd\u6570\uff0c
\n\u6211\u4eec\u8fdb\u5165\u5230\u8be5\u51fd\u6570\uff1a
\nfile = fopen(INITTAB, “r”);
\n#define INITTAB\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0“\/etc\/inittab”
\n\u7531\u6b64\u53ef\u4ee5\u77e5\u9053init\u8fdb\u7a0b\u8bfb\u53d6\u7684\u914d\u7f6e\u6587\u4ef6\u5c31\u662f\/etc\/inittab,busybox\u4e2d\u7684inittab\u6587\u4ef6\u4e2d\u89c4\u5b9a\u4e86\/etc\/inittab\u5185\u5bb9\u7684\u586b\u5199\u683c\u5f0f\u5982\u4e0b\uff1a
\n<id>:<runlevel>:<action>:<process>
\nId:id\u4f1a\u52a0\u4e0a\u4e00\u4e2a\/dev\u524d\u7f00\u4f5c\u4e3a\u4e00\u4e2a\u63a7\u5236\u7ec8\u7aef\uff08stdin\uff0cstdout\uff0cstderr\uff09
\nRunlevel\uff1a\u5ffd\u7565
\nAction\uff1a\u6267\u884c\u7684\u65f6\u673a,\u5305\u62ecSYSINIT\uff0cWAIT\uff0cONCE\uff0c RESPAWN\uff0cASKFIRST\u7b49
\nProcess\uff1a\u8981\u6267\u884c\u7684\u5e94\u7528\u7a0b\u5e8f\u6216\u8005\u811a\u672c
\n\u7ee7\u7eed\u5206\u6790parse_inittab\uff08\uff09\uff1a
\nif (file == NULL)
\n{
\nnew_init_action(CTRLALTDEL, “reboot”, “”);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0new_init_action(SHUTDOWN, “umount -a -r”, “”);
\nnew_init_action(RESTART, “init”, “”);
\nnew_init_action(ASKFIRST, bb_default_login_shell, “”);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0new_init_action(ASKFIRST,bb_default_login_shell,VC_2);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0new_init_action(ASKFIRST,bb_default_login_shell,VC_3);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0new_init_action(ASKFIRST,bb_default_login_shell,VC_4);
\nnew_init_action(SYSINIT, INIT_SCRIPT, “”);
\nreturn;
\n#if ENABLE_FEATURE_USE_INITTAB
\n}
\n\u5982\u679c\u914d\u7f6e\u6587\u4ef6\/etc\/inittab\u4e0d\u5b58\u5728\u7684\u8bdd\u5219\u6267\u884cif\u8bed\u53e5\uff0c\u4e5f\u5c31\u662f\u8bf4\u5982\u679c\u6ca1\/etc\/inittab\u7684\u8bddinit\u8fdb\u7a0b\u4f1a\u76f4\u63a5\u8c03\u7528new_init_action\u6765\u6784\u9020\u9ed8\u8ba4\u914d\u7f6e\u9879\uff0c\u6839\u636eif\u8bed\u53e5\u91cc\u7684\u5185\u5bb9\uff0c\u6211\u4eec\u53ef\u4ee5\u53cd\u63a8\u51fa\u7b49\u6548\u7684\/etc\/inittab\u7684\u5185\u5bb9\u5982\u4e0b\uff1a
\n\uff1a\uff1aCTRLALTDEL\uff1areboot
\n\uff1a\uff1aSHUTDOWN\uff1aumount -a \u2013r
\n\uff1a\uff1aRESTART\uff1ainit
\n\uff1a\uff1aASKFIRST\uff1a-\/bin\/ah
\ntty2:: ASKFIRST:-\/bin\/sh
\ntty3:: ASKFIRST:-\/bin\/sh
\ntty4:: ASKFIRST:-\/bin\/sh
\n::SYSINIT:\/etc\/init.d\/rcS<\/p>\n

\u7ee7\u7eed\u5206\u6790parse_inittab\uff08\uff09\uff1a
\n\u540e\u9762\u5c31\u662f\u5bf9\u914d\u7f6e\u6587\u4ef6\/etc\/inittab\u91cc\u7684\u5185\u5bb9\u91cc\u7684\u89e3\u6790\u4e86\uff0c\u5982#\u5219\u89c6\u4f5c\u6ce8\u91ca\u7b49\u7b49\uff0c\u6700\u540e\u5c31\u8c03\u7528 new_init_action(a->action, command, id);\u5c06\/etc\/inittab\u91cc\u7684\u6bcf\u4e00\u6761\u914d\u7f6e\u9879\u505a\u6210\u4e00\u4e2ainit_action\u7ed3\u6784\u4f53\u5e76\u6dfb\u52a0\u5230\u5177\u6709\u76f8\u540c\u6267\u884c\u65f6\u673a\u7684init_action_list \u4e2d\u53bb\u3002\u8bf4\u5230\u5e95\u89e3\u6790\/etc\/inittab\u8fd9\u4e2a\u914d\u7f6e\u6587\u4ef6\u5c31\u662f\u4e3a\u4e86\u628a\u5404\u914d\u7f6e\u9879\u6dfb\u52a0\u5230\u5bf9\u5e94\u7684init_action_list\u4e2d\u53bb\u3002
\n\u8fd9\u6837parse_inittab\uff08\uff09\u8fd9\u4e2a\u51fd\u6570\u5c31\u7ed3\u675f\u4e86\uff0c\u6211\u4eec\u7ee7\u7eed\u770binit_main\uff08\uff09\u8fd9\u4e2a\u51fd\u6570\uff1a
\n4.\u5f00\u59cb\u8fd0\u884cparse_inittab()\u5e2e\u6211\u4eec\u6dfb\u52a0\u5230init_action_list\u4e2d\u7684\u7a0b\u5e8f\u6216\u811a\u672c\uff1a<\/strong>
\nrun_actions(SYSINIT);
\nrun_actions(WAIT);
\nrun_actions(ONCE);
\nwhile (1)
\n{
\nrun_actions(RESPAWN);
\nrun_actions(ASKFIRST);
\n}
\nrun_actions\u4e3a\u8fd0\u884c\u4e00\u7c7b\u7a0b\u5e8f\u6216\u811a\u672c\uff0c\u8fd9\u91cc\u7684\u4e00\u7c7b\u5c31\u662f\u6309\u7167\u6267\u884c\u65f6\u673a\u6765\u5206\u7c7b\u7684\u3002\u7531\u4e0a\u9762\u8fd9\u6bb5\u4ee3\u7801\u6211\u4eec\u5c31\u53ef\u4ee5\u770b\u51fa\u6267\u884c\u65f6\u673a\u7684\u4f18\u5148\u7ea7\u4e86\uff1aSYSINIT> WAIT> ONCE> RESPAWN> ASKFIRST\uff0c\u5177\u4f53\u7684\u53ef\u4ee5\u7ee7\u7eed\u5206\u6790\u6e90\u7801<\/div>\n","protected":false},"excerpt":{"rendered":"

1.uboot\u542f\u52a8\u5185\u6838\u7684\u4ee3\u7801\u7f29\u51cf\u5982\u4e0b\uff1a s = getenv (“bootcmd”); […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-1525","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"http:\/\/www.51cos.com\/index.php?rest_route=\/wp\/v2\/posts\/1525","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.51cos.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.51cos.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.51cos.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.51cos.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1525"}],"version-history":[{"count":0,"href":"http:\/\/www.51cos.com\/index.php?rest_route=\/wp\/v2\/posts\/1525\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.51cos.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1525"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.51cos.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1525"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.51cos.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1525"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}