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此外目前我在gitHub上准备一些李航的《统计学习方法》的实现算法，目标将书内算法全部手打实现，欢迎参观并打星。GitHib传送门
到这里uboot差不多已经结束了，再完成最后一步，就能启动内核啦。
一. 首先先解决启动时的一个警告，这个和裁剪无关，只是先把警告消除掉
*** Warning - bad CRC, using default environment这句话意思就是环境没有配置，搜索这句话是哪里打出来的 a.在env_common.c文件内的下面这个函数
void set_default_env(const char *s) { if (sizeof(default_environment) > ENV_SIZE) { puts("*** Error - default environment is too large\n\n"); return; } if (s) { if (*s == '!') { printf("*** Warning - %s, " "using default environment\n\n", s + 1); } else { puts(s); } } else { puts("Using default environment\n\n"); } if (himport_r(&env_htab, (char *)default_environment, sizeof(default_environment), '\0', 0) == 0) error("Environment import failed: errno = %d\n", errno); gd->flags |= GD_FLG_ENV_READY; }进入default_environment结构体看看
const uchar default_environment[] = { #ifdef CONFIG_BOOTARGS "bootargs=" CONFIG_BOOTARGS "\0" #endif #ifdef CONFIG_BOOTCOMMAND "bootcmd=" CONFIG_BOOTCOMMAND "\0" #endif #ifdef CONFIG_RAMBOOTCOMMAND "ramboot=" CONFIG_RAMBOOTCOMMAND "\0" #endif #ifdef CONFIG_NFSBOOTCOMMAND "nfsboot=" CONFIG_NFSBOOTCOMMAND "\0" #endif #if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0) "bootdelay=" MK_STR(CONFIG_BOOTDELAY) "\0" #endif #if defined(CONFIG_BAUDRATE) && (CONFIG_BAUDRATE >= 0) "baudrate=" MK_STR(CONFIG_BAUDRATE) "\0" #endif #ifdef CONFIG_LOADS_ECHO "loads_echo=" MK_STR(CONFIG_LOADS_ECHO) "\0" #endif #ifdef CONFIG_ETHADDR "ethaddr=" MK_STR(CONFIG_ETHADDR) "\0" #endif #ifdef CONFIG_ETH1ADDR "eth1addr=" MK_STR(CONFIG_ETH1ADDR) "\0" #endif #ifdef CONFIG_ETH2ADDR "eth2addr=" MK_STR(CONFIG_ETH2ADDR) "\0" #endif #ifdef CONFIG_ETH3ADDR "eth3addr=" MK_STR(CONFIG_ETH3ADDR) "\0" #endif #ifdef CONFIG_ETH4ADDR "eth4addr=" MK_STR(CONFIG_ETH4ADDR) "\0" #endif #ifdef CONFIG_ETH5ADDR "eth5addr=" MK_STR(CONFIG_ETH5ADDR) "\0" #endif #ifdef CONFIG_IPADDR "ipaddr=" MK_STR(CONFIG_IPADDR) "\0" #endif #ifdef CONFIG_SERVERIP "serverip=" MK_STR(CONFIG_SERVERIP) "\0" #endif #ifdef CONFIG_SYS_AUTOLOAD "autoload=" CONFIG_SYS_AUTOLOAD "\0" #endif #ifdef CONFIG_PREBOOT "preboot=" CONFIG_PREBOOT "\0" #endif #ifdef CONFIG_ROOTPATH "rootpath=" CONFIG_ROOTPATH "\0" #endif #ifdef CONFIG_GATEWAYIP "gatewayip=" MK_STR(CONFIG_GATEWAYIP) "\0" #endif #ifdef CONFIG_NETMASK "netmask=" MK_STR(CONFIG_NETMASK) "\0" #endif #ifdef CONFIG_HOSTNAME "hostname=" MK_STR(CONFIG_HOSTNAME) "\0" #endif #ifdef CONFIG_BOOTFILE "bootfile=" CONFIG_BOOTFILE "\0" #endif #ifdef CONFIG_LOADADDR "loadaddr=" MK_STR(CONFIG_LOADADDR) "\0" #endif #ifdef CONFIG_CLOCKS_IN_MHZ "clocks_in_mhz=1\0" #endif #if defined(CONFIG_PCI_BOOTDELAY) && (CONFIG_PCI_BOOTDELAY > 0) "pcidelay=" MK_STR(CONFIG_PCI_BOOTDELAY) "\0" #endif #ifdef CONFIG_EXTRA_ENV_SETTINGS CONFIG_EXTRA_ENV_SETTINGS #endif "\0" };看到那么多宏定义，头都有点大了。 一个一个往下看，不用全部都看，平时用到的参数看一看，首先是
CONFIG_BOOTDELAY这个是boot启动的时候那个倒计时，默认是5秒，我们可以改成3秒，也可以不改
#define CONFIG_BOOTDELAY 3 /* autoboot after 3 seconds */然后是ip设置
"ipaddr=" MK_STR(CONFIG_IPADDR)将宏修改成如下，可以随便设，只要和网内其他IP不冲突就行了
#define CONFIG_IPADDR 192.168.1.120连带的一些都直接写出来吧，就不一个个说了，这些都挨个设置好
#define CONFIG_NETMASK 255.255.255.0 #define CONFIG_IPADDR 192.168.1.120 #define CONFIG_SERVERIP 192.168.1.101 #define CONFIG_ETHADDR 00:0c:29:d3:fe:1db. 设置环境变量，之前boot里面设置参数的时候，set之后是不能save的，因为没有设置保存地址，所以这里修改保存地址
原先的值：
#define CONFIG_ENV_ADDR (CONFIG_SYS_FLASH_BASE + 0x070000) /* */ #define CONFIG_ENV_IS_IN_FLASH #define CONFIG_ENV_SIZE 0x10000 /* allow to overwrite serial and ethaddr */ #define CONFIG_ENV_OVERWRITE修改后的代码
#if 0 #define CONFIG_ENV_ADDR (CONFIG_SYS_FLASH_BASE + 0x070000) /* */ #define CONFIG_ENV_IS_IN_FLASH #define CONFIG_ENV_SIZE 0x10000 /* allow to overwrite serial and ethaddr */ #define CONFIG_ENV_OVERWRITE #else #define CONFIG_ENV_IS_IN_NAND #define CONFIG_ENV_OFFSET 0x00040000 /* 环境变量保存在40000这个地址 */ #define CONFIG_ENV_SIZE 0x0002000 /* 保存区的长度 */ #define CONFIG_ENV_RANGE CONFIG_ENV_SIZE /* 擦除的长度 */ #endif二. 裁剪内核 进入smdk2440.h，把不需要的功能的宏定义都注释掉或者去掉 a. USB用不着
/************************************************************ * USB support (currently only works with D-cache off) ************************************************************/ //#define CONFIG_USB_OHCI //#define CONFIG_USB_KEYBOARD //#define CONFIG_USB_STORAGE //#define CONFIG_DOS_PARTITIONb. RTC时钟不需要
/************************************************************ * RTC ************************************************************/ //#define CONFIG_RTC_S3C24X0 c.BOOTP /* * BOOTP 看不懂，我就全去掉了 */ //#define CONFIG_BOOTP_BOOTFILESIZE //#define CONFIG_BOOTP_BOOTPATH //#define CONFIG_BOOTP_GATEWAY //#define CONFIG_BOOTP_HOSTNAMEd. 看不懂，去掉一些不眼熟的
/* * Command line configuration. */ #include <config_cmd_default.h> #define CONFIG_CMD_BSP #define CONFIG_CMD_CACHE #define CONFIG_CMD_DATE //#define CONFIG_CMD_DHCP /* 动态获得IP地址 */ #define CONFIG_CMD_ELF #define CONFIG_CMD_NAND #define CONFIG_CMD_PING #define CONFIG_CMD_REGINFO //#define CONFIG_CMD_USBe.文件系统，只要能烧写映像文件就行，用不着文件系统
/* * File system 文件系统 */ //#define CONFIG_CMD_FAT //#define CONFIG_CMD_EXT2 //#define CONFIG_CMD_UBI //#define CONFIG_CMD_UBIFS //#define CONFIG_CMD_MTDPARTS //#define CONFIG_MTD_DEVICE //#define CONFIG_MTD_PARTITIONS //#define CONFIG_YAFFS2 //#define CONFIG_RBTREE编译。果然出现了一堆错误
/work/system/u-boot-2012.04.01/common/cmd_date.c:60: undefined reference to `rtc_reset' /work/system/u-boot-2012.04.01/common/cmd_date.c:63: undefined reference to `rtc_get' /work/system/u-boot-2012.04.01/common/cmd_date.c:72: undefined reference to `rtc_set' /work/system/u-boot-2012.04.01/common/cmd_date.c:81: undefined reference to `rtc_get' drivers/mtd/ubi/libubi.o: In function `ubi_detach_mtd_dev': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/build.c:925: undefined reference to `put_mtd_device' drivers/mtd/ubi/libubi.o: In function `open_mtd_device': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/build.c:957: undefined reference to `get_mtd_device_nm' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/build.c:959: undefined reference to `get_mtd_device' drivers/mtd/ubi/libubi.o: In function `ubi_init': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/build.c:1023: undefined reference to `put_mtd_device' drivers/mtd/ubi/libubi.o: In function `process_lvol': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/vtbl.c:381: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/vtbl.c:381: undefined reference to `rb_next' drivers/mtd/ubi/libubi.o: In function `ubi_eba_init_scan': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/eba.c:1193: undefined reference to `rb_first' drivers/mtd/ubi/libubi.o: In function `ubi_scan_move_to_list': /work/system/u-boot-2012.04.01/include/../drivers/mtd/ubi/scan.h:146: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `ubi_eba_init_scan': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/eba.c:1193: undefined reference to `rb_next' drivers/mtd/ubi/libubi.o: In function `leb_write_unlock': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/eba.c:322: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `leb_read_unlock': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/eba.c:238: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `ltree_add_entry': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/eba.c:191: undefined reference to `rb_insert_color' drivers/mtd/ubi/libubi.o: In function `find_wl_entry': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:419: undefined reference to `rb_first' drivers/mtd/ubi/libubi.o: In function `ensure_wear_leveling': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:999: undefined reference to `rb_first' drivers/mtd/ubi/libubi.o: In function `prot_tree_del': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:574: undefined reference to `rb_erase' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:575: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `wl_tree_add': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:241: undefined reference to `rb_insert_color' drivers/mtd/ubi/libubi.o: In function `ubi_wl_init_scan': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:1515: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:1516: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:1516: undefined reference to `rb_next' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:1515: undefined reference to `rb_next' drivers/mtd/ubi/libubi.o: In function `check_protection_over': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:665: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:675: undefined reference to `rb_erase' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:676: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `ubi_wl_scrub_peb': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:1266: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `ubi_wl_put_peb': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:1204: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `prot_tree_add': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:389: undefined reference to `rb_insert_color' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:403: undefined reference to `rb_insert_color' drivers/mtd/ubi/libubi.o: In function `wear_leveling_worker': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:796: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:805: undefined reference to `rb_erase' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:811: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:814: undefined reference to `rb_erase' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:819: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `ubi_wl_get_peb': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:498: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:500: undefined reference to `rb_last' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:518: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/wl.c:533: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `ubi_scan_rm_volume': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:634: undefined reference to `rb_erase' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:632: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:638: undefined reference to `rb_erase' drivers/mtd/ubi/libubi.o: In function `add_volume': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:219: undefined reference to `rb_insert_color' drivers/mtd/ubi/libubi.o: In function `ubi_scan_add_used': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:556: undefined reference to `rb_insert_color' drivers/mtd/ubi/libubi.o: In function `ubi_scan': /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:958: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:959: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:959: undefined reference to `rb_next' /work/system/u-boot-2012.04.01/drivers/mtd/ubi/scan.c:958: undefined reference to `rb_next' fs/ext2/libext2fs.o: In function `ext2fs_set_blk_dev': /work/system/u-boot-2012.04.01/fs/ext2/dev.c:44: undefined reference to `get_partition_info' fs/fat/libfat.o: In function `file_fat_detectfs': /work/system/u-boot-2012.04.01/fs/fat/fat.c:1162: undefined reference to `dev_print' fs/fat/libfat.o: In function `fat_register_device': /work/system/u-boot-2012.04.01/fs/fat/fat.c:79: undefined reference to `get_partition_info' fs/ubifs/libubifs.o: In function `insert_old_idx': /work/system/u-boot-2012.04.01/fs/ubifs/tnc.c:105: undefined reference to `rb_insert_color' fs/ubifs/libubifs.o: In function `ubifs_add_bud': /work/system/u-boot-2012.04.01/fs/ubifs/log.c:86: undefined reference to `rb_insert_color' fs/ubifs/libubifs.o: In function `insert_dead_orphan': /work/system/u-boot-2012.04.01/fs/ubifs/orphan.c:129: undefined reference to `rb_insert_color' fs/ubifs/libubifs.o: In function `ubifs_recover_size': /work/system/u-boot-2012.04.01/fs/ubifs/recovery.c:1171: undefined reference to `rb_first' /work/system/u-boot-2012.04.01/fs/ubifs/recovery.c:1214: undefined reference to `rb_next' /work/system/u-boot-2012.04.01/fs/ubifs/recovery.c:1220: undefined reference to `rb_next' /work/system/u-boot-2012.04.01/fs/ubifs/recovery.c:1221: undefined reference to `rb_erase' fs/ubifs/libubifs.o: In function `add_ino': /work/system/u-boot-2012.04.01/fs/ubifs/recovery.c:1050: undefined reference to `rb_insert_color' fs/ubifs/libubifs.o: In function `remove_ino': /work/system/u-boot-2012.04.01/fs/ubifs/recovery.c:1088: undefined reference to `rb_erase' fs/ubifs/libubifs.o: In function `insert_node': /work/system/u-boot-2012.04.01/fs/ubifs/replay.c:373: undefined reference to `rb_insert_color' fs/ubifs/libubifs.o: In function `insert_dent': /work/system/u-boot-2012.04.01/fs/ubifs/replay.c:448: undefined reference to `rb_insert_color' fs/ubifs/libubifs.o: In function `insert_ref_node': /work/system/u-boot-2012.04.01/fs/ubifs/replay.c:689: undefined reference to `rb_insert_color' fs/ubifs/libubifs.o: In function `apply_replay_tree': /work/system/u-boot-2012.04.01/fs/ubifs/replay.c:306: undefined reference to `rb_next' /work/system/u-boot-2012.04.01/fs/ubifs/replay.c:294: undefined reference to `rb_first' make: *** [u-boot] Error 1 book@book-desktop:/work/system/u-boot-2012.04.01$看第一个错误，rtc的cmd_date有问题，把这个的宏也直接注释掉
//#define CONFIG_CMD_DATE然后看下面的错误，好像都和ubi有关，但是ubi已经去掉了啊，可能没有make clean。 先make clean，然后再重新编译。 果然没有错误了。 看一下bin有多大
ls -l u-boot.bin返回：
-rwxr-xr-x 1 book book 216844 2016-08-13 23:38 u-boot.bin两百多k，原先是400多K，的确小了很多。
三. 划分分区 划分区不能随便画，要看一下使用的内核是打算怎么分的，不然两边数据读取的时候都对不上。 tftp下载uImage内核，bootm启动，这个在之前应该写过，内核会在内核中启动，重新上电就没有了，测试的时候很方便，启动内核以后在打出来的数据里查看分区，它是这样写的
0x00000000-0x00040000 : "bootloader" 0x00040000-0x00060000 : "params" 0x00060000-0x00260000 : "kernel" 0x00260000-0x10000000 : "root"我们boot也照着这个样子分区好了。命令mtdpart是和分区有关的，查找boot里有没有名字是mtdpart的文件，找到cmd_mtdpart，找到里面的初始化函数mtdparts_init，里面太乱了，还是看看别人怎么用好了，搜索这个关键词，随便进入一个文件，看到别人这么写的
#define CONFIG_CMD_MTDPARTS #define MTDIDS_DEFAULT "nor0=TQM8xxM-0" /* 表示哪一个设备 */ #define MTDPARTS_DEFAULT "mtdparts=TQM8xxM-0:512k(u-boot)," \ "128k(params)," \ "1920k(kernel)," \ "5632(rootfs)," \ "4m(data)" \直接复制到2440.h，修改"nor0=TQM8xxM-0"中的nor为nand，“TQM8xxM”改为“jz2440”（两个TQM8xxM都要改为一致，我当时就是只改了一个，报错如下）
invalid mtd device 'TQM8xxM-0'(u-boot)的大小改为256k，params改为128k，kernel改为2m，rootfs改为“-”，“-”表示剩下的空间，(data)直接删掉，注意rootfs后面的逗号一定要去掉，我之前没去掉，报错
no partitions allowed after a fill-up partition后来查代码才发现，只要后面有逗号，它就会认为下面还有划分空间，这时候你又已经写了“-”表示这段空间到末尾，所以会报错。 所以整段代码改为
#define CONFIG_CMD_MTDPARTS #define MTDIDS_DEFAULT "nand0=jz2440-0" /* 表示哪一个设备 */ #define MTDPARTS_DEFAULT "mtdparts=jz2440-0:256k(u-boot)," \ "128k(params)," \ "2m(kernel)," \ "-(rootfs)" \最后还要到board.c的
for (;;) { main_loop(); }之前加上一句话
run_command("mtdparts default", 0);这是命令mtdparts default，就是说每次boot启动以后先分区，因为分区是我们程序软规定的，每次启动都要规定一下。
编译，没有错误，烧写。
四. 测试分区是否好使 a. 输入命令mtd，返回结果：
device nand0 <jz2440-0>, # parts = 4 #: name size offset mask_flags 0: u-boot 0x00040000 0x00000000 0 1: params 0x00020000 0x00040000 0 2: kernel 0x00200000 0x00060000 0 3: rootfs 0x0fda0000 0x00260000 0已经分区成功了 b. 使用TFTP下载,把名为uImage的内核下载到30000000的地址
tftp 30000000 uImagec. 擦除内核要使用的分区
nand erase.part kerneld. 将内核写入kernel
nand write.part kernele. 重启，等待3秒结束后启动内核， f. 启动成功
