• 一、主要是start.S 里面的 board_init_f 以及 board_init_r 函数分析，MLO与 u-boot.omg 的区别就在这里

• 二、 MLO 加载完毕，他会重新回到 start.S 重新开始

• 三、 board_init_f 函数的实现在 arch/arm/lib/board.c 里面

    264 void board_init_f(ulong bootflag)265 {   266     bd_t *bd;267     init_fnc_t **init_fnc_ptr;268     gd_t *id;269     ulong addr, addr_sp;270     271 272     /* Pointer is writable since we allocated a register for it */273     gd = (gd_t *) ((CONFIG_SYS_INIT_SP_ADDR) & ~0x07);274     /* compiler optimization barrier needed for GCC >= 3.4 */275     __asm__ __volatile__("": : :"memory");276     277     memset((void *)gd, 0, sizeof(gd_t));278 279     gd->mon_len = _bss_end_ofs;280     // 这里有一个函数指针数组，里面包含很多初始化281     for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {282         if ((*init_fnc_ptr)() != 0) {283             hang ();284         }285     }// ... ...412     gd->bd->bi_baudrate = gd->baudrate;413     /* Ram ist board specific, so move it to board code ... */414     dram_init_banksize();415     display_dram_config();  /* and display it */416 417     gd->relocaddr = addr;418     gd->start_addr_sp = addr_sp;419     gd->reloc_off = addr - _TEXT_BASE;420     debug("relocation Offset is: %08lx\n", gd->reloc_off);421     memcpy(id, (void *)gd, sizeof(gd_t));422 423     relocate_code(addr_sp, id, addr);   // 最后回到 start.S  然后又到了 board_init_r424 425     /* NOTREACHED - relocate_code() does not return */426 }

• 接上函数指针数组 init_sequence

    235 init_fnc_t *init_sequence[] = {236 #if defined(CONFIG_ARCH_CPU_INIT)237     arch_cpu_init,      /* basic arch cpu dependent setup */238 #endif239 #if defined(CONFIG_BOARD_EARLY_INIT_F)240     board_early_init_f,241 #endif242     timer_init,     /* initialize timer */243 #ifdef CONFIG_FSL_ESDHC244     get_clocks,245 #endif246     env_init,       /* initialize environment */247     init_baudrate,      /* initialze baudrate settings */248     serial_init,        /* serial communications setup */249     console_init_f,     /* stage 1 init of console */250     display_banner,     /* say that we are here */251 #if defined(CONFIG_DISPLAY_CPUINFO)252     print_cpuinfo,      /* display cpu info (and speed) */253 #endif254 #if defined(CONFIG_DISPLAY_BOARDINFO)255     checkboard,     /* display board info */256 #endif257 #if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)258     init_func_i2c,259 #endif260     dram_init,      /* configure available RAM banks */261     NULL,262 };

• 三、board_init_r 也在 arch/arm/lib/board.c

    443 void board_init_r(gd_t *id, ulong dest_addr)444 {445     char *s;446     bd_t *bd;447     ulong malloc_start;448 #if !defined(CONFIG_SYS_NO_FLASH)449     ulong flash_size;450 #endif451 452 453     gd = id;454     bd = gd->bd;455 456     gd->flags |= GD_FLG_RELOC;  /* tell others: relocation done */457 458     monitor_flash_len = _end_ofs;459 460     /* Enable caches */461     enable_caches();462 463     debug("monitor flash len: %08lX\n", monitor_flash_len);464     board_init();   /* Setup chipselects */465 466 #ifdef CONFIG_SERIAL_MULTI467     serial_initialize();468 469 #endif81     /* The Malloc area is immediately below the monitor copy in DRAM */482     malloc_start = dest_addr - TOTAL_MALLOC_LEN;483     mem_malloc_init (malloc_start, TOTAL_MALLOC_LEN);484 485     stdio_init();   /* get the devices list going. */486 487     puts("zengjf :\n");523 #if defined(CONFIG_CMD_NAND)524     puts("NAND :  ");525     nand_init();        /* go init the NAND */526 #endif// ... ... 531 532 #ifdef CONFIG_GENERIC_MMC533        puts("MMC:   ");534        mmc_initialize(bd);535 #endif// .. ...559 560     console_init_r();   /* fully init console as a device */561     566 #if defined(CONFIG_MISC_INIT_R)567     /* miscellaneous platform dependent initialisations */    568     misc_init_r();569 #endif// ... ...649     for (;;) {650         main_loop();651     }652 653     /* NOTREACHED - no way out of command loop except booting */654 }

• u-boot 加载 kernel 参考：

  http://www.cnblogs.com/chenfulin5/p/6937334.html

• MLO 的流程参考：

  http://www.cnblogs.com/chenfulin5/p/8398399.html