最近项目原因，要在uboot中增加内核验校和内核损坏修复功能，所以需要回头看看uboot。这次选择了uboot2015来进行分析
uboot是明远睿智提供的。
下载地址 链接：https://pan.baidu.com/s/13SuRii3WTqvFTNIsSS9GAg 密码：65zz
环境：ubuntu16
主控：imx6q
因为我们这款cpu指令集是armv7的所以选择这个目录下的start.s，如果不知道自己该看那个目录下的start.s，可以用如下方法
先编译uboot，编译成功后，执行 find -name start.0 即可看见start文件所在目录
然后我们来看看代码，我对代码进行了删减，我们目的在于流程分析，就不分析具体每句话了
reset: /* Allow the board to save important registers */ b save_boot_params save_boot_params_ret: /* * disable interrupts (FIQ and IRQ), also set the cpu to SVC32 mode, * except if in HYP mode already */ 。。。。。。。。 /* * Setup vector: * (OMAP4 spl TEXT_BASE is not 32 byte aligned. * Continue to use ROM code vector only in OMAP4 spl) */ # if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD)) /* Set V= 0 in CP15 SCTLR register - for VBAR to point to vector */ 。。。。。。。。。 /* Set vector address in CP15 VBAR register */ 。。。。。。。。。 #endif /* the mask ROM code should have PLL and others stable */ #ifndef CONFIG_SKIP_LOWLEVEL_INIT bl cpu_init_cp15 bl cpu_init_crit #endif bl _main //进入_main 123456789101112131415161718192021222324252627282930arch\arm\lib\crt0.S _main在这个文件里
ENTRY(_main) /* * Set up initial C runtime environment and call board_init_f(0). */ #if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK) ldr sp, =(CONFIG_SPL_STACK) #else ldr sp, =(CONFIG_SYS_INIT_SP_ADDR) #endif 。。。。。。。 clr_gd: 。。。。。。。 #if defined(CONFIG_SYS_MALLOC_F_LEN) sub sp, sp, #CONFIG_SYS_MALLOC_F_LEN str sp, [r9, #GD_MALLOC_BASE] #endif /* mov r0, #0 not needed due to above code */ bl board_init_f /*这个函数把uboot拷贝到ram*/ #if ! defined(CONFIG_SPL_BUILD) /* * Set up intermediate environment (new sp and gd) and call * relocate_code(addr_moni). Trick here is that we'll return * 'here' but relocated. */ 。。。。。。 b relocate_code here: /* * now relocate vectors */ bl relocate_vectors /* Set up final (full) environment */ bl c_runtime_cpu_setup /* we still call old routine here */ #endif #if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_FRAMEWORK) # ifdef CONFIG_SPL_BUILD /* Use a DRAM stack for the rest of SPL, if requested */ bl spl_relocate_stack_gd cmp r0, #0 movne sp, r0 # endif ldr r0, =__bss_start /* this is auto-relocated! */ #ifdef CONFIG_USE_ARCH_MEMSET ldr r3, =__bss_end /* this is auto-relocated! */ mov r1, #0x00000000 /* prepare zero to clear BSS */ subs r2, r3, r0 /* r2 = memset len */ bl memset #else ldr r1, =__bss_end /* this is auto-relocated! */ mov r2, #0x00000000 /* prepare zero to clear BSS */ clbss_l:cmp r0, r1 /* while not at end of BSS */ strlo r2, [r0] /* clear 32-bit BSS word */ addlo r0, r0, #4 /* move to next */ blo clbss_l #endif #if ! defined(CONFIG_SPL_BUILD) bl coloured_LED_init bl red_led_on #endif /* call board_init_r(gd_t *id, ulong dest_addr) */ mov r0, r9 /* gd_t */ ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */ /* call board_init_r */ ldr pc, =board_init_r /* this is auto-relocated! */ /* we should not return here. */ #endif ENDPROC(_main) 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081然后调用了 board_init_r 函数
common\board_r.c
void board_init_r(gd_t *new_gd, ulong dest_addr) { #ifdef CONFIG_NEEDS_MANUAL_RELOC int i; #endif #ifdef CONFIG_AVR32 mmu_init_r(dest_addr); #endif #if !defined(CONFIG_X86) && !defined(CONFIG_ARM) && !defined(CONFIG_ARM64) gd = new_gd; #endif #ifdef CONFIG_NEEDS_MANUAL_RELOC for (i = 0; i < ARRAY_SIZE(init_sequence_r); i++) init_sequence_r[i] += gd->reloc_off; #endif if (initcall_run_list(init_sequence_r)) //只是一个函数指针的数组，里面包含了一系列初始化函数 hang(); /* NOTREACHED - run_main_loop() does not return */ hang(); } 12345678910111213141516171819202122232425我们来看看这个init_sequence_r 为了更加清晰的看到他的流程，我删减了一部分代码
init_fnc_t init_sequence_r[] = { initr_trace, initr_reloc, /* TODO: could x86/PPC have this also perhaps? */ #ifdef CONFIG_ARM initr_caches, #endif initr_reloc_global_data, 。。。。。。。 board_init, /* Setup chipselects */ #endif /* * TODO: printing of the clock inforamtion of the board is now * implemented as part of bdinfo command. Currently only support for * davinci SOC's is added. Remove this check once all the board * implement this. */ 。。。。。。。。 INIT_FUNC_WATCHDOG_RESET #ifdef CONFIG_SYS_DELAYED_ICACHE initr_icache_enable, #endif #if defined(CONFIG_PCI) && defined(CONFIG_SYS_EARLY_PCI_INIT) /* * Do early PCI configuration _before_ the flash gets initialised, * because PCU ressources are crucial for flash access on some boards. */ initr_pci, #endif 。。。。。。。 #ifdef CONFIG_ARCH_MISC_INIT arch_misc_init, /* miscellaneous arch-dependent init */ #endif #ifdef CONFIG_MISC_INIT_R misc_init_r, /* miscellaneous platform-dependent init */ #endif INIT_FUNC_WATCHDOG_RESET 。。。。。。。 #if defined(CONFIG_X86) || defined(CONFIG_MICROBLAZE) || defined(CONFIG_AVR32) \ || defined(CONFIG_M68K) timer_init, /* initialize timer */ #endif INIT_FUNC_WATCHDOG_RESET /* * Some parts can be only initialized if all others (like * Interrupts) are up and running (i.e. the PC-style ISA * keyboard). */ last_stage_init, #endif #ifdef CONFIG_CMD_BEDBUG INIT_FUNC_WATCHDOG_RESET initr_bedbug, #endif #if defined(CONFIG_PRAM) || defined(CONFIG_LOGBUFFER) initr_mem, #endif #ifdef CONFIG_PS2KBD initr_kbd, #endif #ifdef CONFIG_FSL_FASTBOOT initr_check_fastboot, #endif run_main_loop, }; 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869这里满足宏条件的函数都会被执行，最后一个执行的函数是run_main_loop，我继续追踪下去，这个函数 还是在这个文件中board_r.c
static int run_main_loop(void) { #ifdef CONFIG_SANDBOX sandbox_main_loop_init(); #endif /* main_loop() can return to retry autoboot, if so just run it again */ for (;;) //死循环 main_loop(); return 0; } 12345678910可以看见，这里是单向的，调用了run_main_loop就不会返回了，我们继续看看main_loop();
common\main.c
/* We come here after U-Boot is initialised and ready to process commands */ void main_loop(void) { const char *s; 。。。。。。。。。 puts("#test!!!!!!!!!!!!!!!!!!!!!!!\n"); modem_init(); #ifdef CONFIG_VERSION_VARIABLE setenv("ver", version_string); /* set version variable */ #endif /* CONFIG_VERSION_VARIABLE */ cli_init(); run_preboot_environment_command(); #if defined(CONFIG_UPDATE_TFTP) update_tftp(0UL); #endif /* CONFIG_UPDATE_TFTP */ s = bootdelay_process(); //uboot读秒，等待用户按键 if (cli_process_fdt(&s)) cli_secure_boot_cmd(s); printf("flag2"); autoboot_command(s); //用户没有按键，执行环境参数命令 cli_loop(); } 123456789101112131415161718192021222324252627282930我们 继续进入到 autoboot_command(s);
void autoboot_command(const char *s) { debug("### main_loop: bootcmd=\"%s\"\n", s ? s : "<UNDEFINED>"); if (stored_bootdelay != -1 && s && !abortboot(stored_bootdelay)) { #if defined(CONFIG_AUTOBOOT_KEYED) && !defined(CONFIG_AUTOBOOT_KEYED_CTRLC) int prev = disable_ctrlc(1); /* disable Control C checking */ #endif run_command_list(s, -1, 0); //传递过来的命令流s会在这里被解析执行 #if defined(CONFIG_AUTOBOOT_KEYED) && !defined(CONFIG_AUTOBOOT_KEYED_CTRLC) disable_ctrlc(prev); /* restore Control C checking */ #endif } #ifdef CONFIG_MENUKEY if (menukey == CONFIG_MENUKEY) { s = getenv("menucmd"); if (s) run_command_list(s, -1, 0); } #endif /* CONFIG_MENUKEY */ } 123456789101112131415161718192021222324对于命令的解析执行，我们追踪 run_command_list(s, -1, 0);来分析分析
int run_command_list(const char *cmd, int len, int flag) { int need_buff = 1; char *buff = (char *)cmd; /* cast away const */ int rcode = 0; if (len == -1) { len = strlen(cmd); #ifdef CONFIG_SYS_HUSH_PARSER /* hush will never change our string */ need_buff = 0; #else /* the built-in parser will change our string if it sees \n */ need_buff = strchr(cmd, '\n') != NULL; #endif } if (need_buff) { buff = malloc(len + 1); if (!buff) return 1; memcpy(buff, cmd, len); buff[len] = '\0'; } #ifdef CONFIG_SYS_HUSH_PARSER rcode = parse_string_outer(buff, FLAG_PARSE_SEMICOLON); #else 。。。。。。。。。 #endif return rcode; } 12345678910111213141516171819202122232425262728293031继续追踪parse_string_outer(buff, FLAG_PARSE_SEMICOLON);
#ifndef __U_BOOT__ static int parse_string_outer(const char *s, int flag) #else int parse_string_outer(const char *s, int flag) #endif /* __U_BOOT__ */ { struct in_str input; #ifdef __U_BOOT__ char *p = NULL; int rcode; if (!s) return 1; if (!*s) return 0; if (!(p = strchr(s, '\n')) || *++p) { p = xmalloc(strlen(s) + 2); strcpy(p, s); strcat(p, "\n"); setup_string_in_str(&input, p); rcode = parse_stream_outer(&input, flag); free(p); return rcode; } else { #endif setup_string_in_str(&input, s); return parse_stream_outer(&input, flag); #ifdef __U_BOOT__ } #endif } 1234567891011121314151617181920212223242526272829303132这里主要是对命令流进行了分割、执行。我们再继续追踪 parse_stream_outer(&input, flag);
/* most recursion does not come through here, the exeception is * from builtin_source() */ static int parse_stream_outer(struct in_str *inp, int flag) { struct p_context ctx; o_string temp=NULL_O_STRING; int rcode; #ifdef __U_BOOT__ int code = 1; #endif do { ctx.type = flag; initialize_context(&ctx); update_ifs_map(); if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) mapset((uchar *)";$&|", 0); inp->promptmode=1; rcode = parse_stream(&temp, &ctx, inp, flag & FLAG_CONT_ON_NEWLINE ? -1 : '\n'); #ifdef __U_BOOT__ if (rcode == 1) flag_repeat = 0; #endif if (rcode != 1 && ctx.old_flag != 0) { syntax(); #ifdef __U_BOOT__ flag_repeat = 0; #endif } if (rcode != 1 && ctx.old_flag == 0) { done_word(&temp, &ctx); done_pipe(&ctx,PIPE_SEQ); #ifndef __U_BOOT__ run_list(ctx.list_head); //执行命令 #else 。。。。。。。。 #endif } else { if (ctx.old_flag != 0) { free(ctx.stack); b_reset(&temp); } #ifdef __U_BOOT__ if (inp->__promptme == 0) printf("<INTERRUPT>\n"); inp->__promptme = 1; #endif temp.nonnull = 0; temp.quote = 0; inp->p = NULL; free_pipe_list(ctx.list_head,0); } b_free(&temp); /* loop on syntax errors, return on EOF */ } while (rcode != -1 && !(flag & FLAG_EXIT_FROM_LOOP) && (inp->peek != static_peek || b_peek(inp))); #ifndef __U_BOOT__ return 0; #else return (code != 0) ? 1 : 0; #endif /* __U_BOOT__ */ } 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960追踪run_list(ctx.list_head);
/* Select which version we will use */ static int run_list(struct pipe *pi) { int rcode=0; #ifndef __U_BOOT__ if (fake_mode==0) { #endif rcode = run_list_real(pi); #ifndef __U_BOOT__ } #endif /* free_pipe_list has the side effect of clearing memory * In the long run that function can be merged with run_list_real, * but doing that now would hobble the debugging effort. */ free_pipe_list(pi,0); return rcode; } 1234567891011121314151617追踪 run_list_real(pi);
static int run_list_real(struct pipe *pi) { char *save_name = NULL; char **list = NULL; char **save_list = NULL; struct pipe *rpipe; int flag_rep = 0; #ifndef __U_BOOT__ int save_num_progs; #endif int rcode=0, flag_skip=1; int flag_restore = 0; int if_code=0, next_if_code=0; /* need double-buffer to handle elif */ reserved_style rmode, skip_more_in_this_rmode=RES_XXXX; /* check syntax for "for" */ for (rpipe = pi; rpipe; rpipe = rpipe->next) { if ((rpipe->r_mode == RES_IN || rpipe->r_mode == RES_FOR) && (rpipe->next == NULL)) { syntax(); #ifdef __U_BOOT__ flag_repeat = 0; #endif return 1; } if ((rpipe->r_mode == RES_IN && (rpipe->next->r_mode == RES_IN && rpipe->next->progs->argv != NULL))|| (rpipe->r_mode == RES_FOR && rpipe->next->r_mode != RES_IN)) { syntax(); #ifdef __U_BOOT__ flag_repeat = 0; #endif return 1; } } for (; pi; pi = (flag_restore != 0) ? rpipe : pi->next) { if (pi->r_mode == RES_WHILE || pi->r_mode == RES_UNTIL || pi->r_mode == RES_FOR) { #ifdef __U_BOOT__ 。。。。。。。。。。 #endif 。。。。。。。。。。 #ifndef __U_BOOT__ pi->progs->glob_result.gl_pathv[0] = pi->progs->argv[0]; #endif continue; } else { /* insert new value from list for variable */ if (pi->progs->argv[0]) free(pi->progs->argv[0]); pi->progs->argv[0] = *list++; #ifndef __U_BOOT__ pi->progs->glob_result.gl_pathv[0] = pi->progs->argv[0]; #endif } } if (rmode == RES_IN) continue; if (rmode == RES_DO) { if (!flag_rep) continue; } if (rmode == RES_DONE) { if (flag_rep) { flag_restore = 1; } else { rpipe = NULL; } } if (pi->num_progs == 0) continue; #ifndef __U_BOOT__ save_num_progs = pi->num_progs; /* save number of programs */ #endif rcode = run_pipe_real(pi); //执行 debug_printf("run_pipe_real returned %d\n",rcode); #ifndef __U_BOOT__ if (rcode!=-1) { /* We only ran a builtin: rcode was set by the return value * of run_pipe_real(), and we don't need to wait for anything. */ } else if (pi->followup==PIPE_BG) { /* XXX check bash's behavior with nontrivial pipes */ /* XXX compute jobid */ /* XXX what does bash do with attempts to background builtins? */ insert_bg_job(pi); rcode = EXIT_SUCCESS; } else { 。。。。。。。 } else { rcode = checkjobs(pi); } debug_printf("checkjobs returned %d\n",rcode); } last_return_code=rcode; #else if (rcode < -1) { last_return_code = -rcode - 2; return -2; /* exit */ } last_return_code=(rcode == 0) ? 0 : 1; #endif #ifndef __U_BOOT__ pi->num_progs = save_num_progs; /* restore number of programs */ #endif if ( rmode == RES_IF || rmode == RES_ELIF ) next_if_code=rcode; /* can be overwritten a number of times */ if (rmode == RES_WHILE) flag_rep = !last_return_code; if (rmode == RES_UNTIL) flag_rep = last_return_code; if ( (rcode==EXIT_SUCCESS && pi->followup==PIPE_OR) || (rcode!=EXIT_SUCCESS && pi->followup==PIPE_AND) ) skip_more_in_this_rmode=rmode; #ifndef __U_BOOT__ checkjobs(NULL); #endif } return rcode; } 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121追踪 rcode = run_pipe_real(pi);
/* run_pipe_real() starts all the jobs, but doesn't wait for anything * to finish. See checkjobs(). * * return code is normally -1, when the caller has to wait for children * to finish to determine the exit status of the pipe. If the pipe * is a simple builtin command, however, the action is done by the * time run_pipe_real returns, and the exit code is provided as the * return value. * * The input of the pipe is always stdin, the output is always * stdout. The outpipe[] mechanism in BusyBox-0.48 lash is bogus, * because it tries to avoid running the command substitution in * subshell, when that is in fact necessary. The subshell process * now has its stdout directed to the input of the appropriate pipe, * so this routine is noticeably simpler. */ static int run_pipe_real(struct pipe *pi) { int i; #ifndef __U_BOOT__ int nextin, nextout; int pipefds[2]; /* pipefds[0] is for reading */ struct child_prog *child; struct built_in_command *x; char *p; # if __GNUC__ /* Avoid longjmp clobbering */ (void) &i; (void) &nextin; (void) &nextout; (void) &child; # endif #else int nextin; int flag = do_repeat ? CMD_FLAG_REPEAT : 0; struct child_prog *child; char *p; # if __GNUC__ /* Avoid longjmp clobbering */ (void) &i; (void) &nextin; (void) &child; # endif #endif /* __U_BOOT__ */ nextin = 0; #ifndef __U_BOOT__ pi->pgrp = -1; #endif /* Check if this is a simple builtin (not part of a pipe). * Builtins within pipes have to fork anyway, and are handled in * pseudo_exec. "echo foo | read bar" doesn't work on bash, either. */ if (pi->num_progs == 1) child = & (pi->progs[0]); #ifndef __U_BOOT__ 。。。。。。。 #else if (pi->num_progs == 1 && child->group) { int rcode; debug_printf("non-subshell grouping\n"); rcode = run_list_real(child->group); #endif return rcode; } else if (pi->num_progs == 1 && pi->progs[0].argv != NULL) { for (i=0; is_assignment(child->argv[i]); i++) { /* nothing */ } if (i!=0 && child->argv[i]==NULL) { /* assignments, but no command: set the local environment */ for (i=0; child->argv[i]!=NULL; i++) { /* Ok, this case is tricky. We have to decide if this is a * local variable, or an already exported variable. If it is * already exported, we have to export the new value. If it is * not exported, we need only set this as a local variable. * This junk is all to decide whether or not to export this * variable. */ int export_me=0; char *name, *value; name = xstrdup(child->argv[i]); debug_printf("Local environment set: %s\n", name); value = strchr(name, '='); if (value) *value=0; #ifndef __U_BOOT__ if ( get_local_var(name)) { export_me=1; } #endif free(name); p = insert_var_value(child->argv[i]); set_local_var(p, export_me); if (p != child->argv[i]) free(p); } return EXIT_SUCCESS; /* don't worry about errors in set_local_var() yet */ } for (i = 0; is_assignment(child->argv[i]); i++) { p = insert_var_value(child->argv[i]); #ifndef __U_BOOT__ putenv(strdup(p)); #else set_local_var(p, 0); #endif if (p != child->argv[i]) { child->sp--; free(p); } } if (child->sp) { char * str = NULL; str = make_string(child->argv + i, child->argv_nonnull + i); parse_string_outer(str, FLAG_EXIT_FROM_LOOP | FLAG_REPARSING); free(str); return last_return_code; } #ifndef __U_BOOT__ 。。。。。。。。 #else /* check ";", because ,example , argv consist from * "help;flinfo" must not execute */ if (strchr(child->argv[i], ';')) { printf("Unknown command '%s' - try 'help' or use " "'run' command\n", child->argv[i]); return -1; } /* Process the command */ return cmd_process(flag, child->argc, child->argv, &flag_repeat, NULL); #endif } 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132追踪 cmd_process(flag, child->argc, child->argv, &flag_repeat, NULL);
enum command_ret_t cmd_process(int flag, int argc, char * const argv[], int *repeatable, ulong *ticks) { enum command_ret_t rc = CMD_RET_SUCCESS; cmd_tbl_t *cmdtp; /* Look up command in command table */ cmdtp = find_cmd(argv[0]); if (cmdtp == NULL) { printf("Unknown command '%s' - try 'help'\n", argv[0]); return 1; } /* found - check max args */ if (argc > cmdtp->maxargs) rc = CMD_RET_USAGE; #if defined(CONFIG_CMD_BOOTD) /* avoid "bootd" recursion */ else if (cmdtp->cmd == do_bootd) { if (flag & CMD_FLAG_BOOTD) { puts("'bootd' recursion detected\n"); rc = CMD_RET_FAILURE; } else { flag |= CMD_FLAG_BOOTD; } } #endif /* If OK so far, then do the command */ if (!rc) { if (ticks) *ticks = get_timer(0); rc = cmd_call(cmdtp, flag, argc, argv); if (ticks) *ticks = get_timer(*ticks); *repeatable &= cmdtp->repeatable; } if (rc == CMD_RET_USAGE) rc = cmd_usage(cmdtp); return rc; } 123456789101112131415161718192021222324252627282930313233343536373839404142命令最终在这里被执行，以上一系列过程 将收到的指令通过一系列字符处理然后加入一个执行列表，然后执行这个列表。这些命令的的具体实现大家可以 执行 find -name ./common/cmd*.c
这些文件里定义了命令的具体实现。
比如我们mmc read xx xx命令，在common\cmd_mmc.c :842中，大家可以具体去看看,其实读秒过后的，系统自动执行了一系列环境变量（）中保存的命令，执行命令这一套的通用的，只是命令的来源不一样，一个是用户输入的，一个是从环境命令中读取的。我们可以做个实验，在parse_string_outer函数中添加如下代码
#ifndef __U_BOOT__ static int parse_string_outer(const char *s, int flag) #else int parse_string_outer(const char *s, int flag) #endif /* __U_BOOT__ */ { struct in_str input; #ifdef __U_BOOT__ char *p = NULL; int rcode; if (!s) return 1; if (!*s) return 0; if (!(p = strchr(s, '\n')) || *++p) { p = xmalloc(strlen(s) + 2) printf("#stream =%s \n", s); //yin strcpy(p, s); strcat(p, "\n"); printf("#hush\n"); //yin setup_string_in_str(&input, p); rcode = parse_stream_outer(&input, flag); free(p); return rcode; } else { #endif setup_string_in_str(&input, s); return parse_stream_outer(&input, flag); #ifdef __U_BOOT__ } #endif } 123456789101112131415161718192021222324252627282930313233343536然后编译，烧写，启动，观察输出信息
U-Boot 2015.04 (Mar 16 2018 - 18:45:12) CPU: Freescale i.MX6Q rev1.5 at 792 MHz CPU: Temperature 35 C Reset cause: POR Board: MYZR i.MX6 Evaluation Kit Model: MY-IMX6-EK314-6Q-1G I2C: ready DRAM: 1 GiB MMC: FSL_SDHC: 0, FSL_SDHC: 1 SF: Detected SST25VF016B with page size 256 Bytes, erase size 4 KiB, total 2 MiB *** Warning - bad CRC, using default environment No panel detected: default to Hannstar-XGA Display: Hannstar-XGA (1024x600) In: serial Out: serial Err: serial Net: using phy at 5 FEC [PRIME] #test!!!!!!!!!!!!!!!!!!!! Normal Boot flag1 flag2Hit any key to stop autoboot: 0 #run start stream = mmc dev ${mmcdev}; if run loadimage; then run mmcboot; else run netboot; fi; #hush switch to partitions #0, OK mmc1(part 0) is current device stream = fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${image_file} #hush reading zImage-myimx6 5602432 bytes read in 157 ms (34 MiB/s) stream = echo Booting from mmc ...; run mmcargs; if run loadfdt; then bootz ${loadaddr} - ${fdt_addr}; else echo WARN: Cannot boot from mmc; fi; #hush Booting from mmc ... stream = run set_disp; setenv bootargs console=${console},${baudrate} ${smp} cma=320M root=${mmcroot} ${disp_args} #hush stream = setenv disp_args ${display} #hush stream = fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file} #hush reading myimx6ek314-6q.dtb 42887 bytes read in 18 ms (2.3 MiB/s) Kernel image @ 0x12000000 [ 0x000000 - 0x557c80 ] ## Flattened Device Tree blob at 18000000 Booting using the fdt blob at 0x18000000 Using Device Tree in place at 18000000, end 1800d786 Starting kernel ... 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950分析到这里想必大家都有了自己想法，剩下的就交给你们去探索了，这里仅仅是个抛砖引玉，做个粗浅的分析，感谢您耐着性子读到这里，哈哈哈~~
lornyin 2018/3/17
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