- 芯片需要支持SD卡这种启动方式。
- 准备好u-boot.imx,dtb,zImage,rootfs压缩包
使用fdisk命令对sd卡分区
输入fdisk /dev/mmcblk0.按照提示输入相关选项进行操作。
/#fdisk/dev/mmcblk0 Device contains neither a valid DOS partition table, nor Sun, SGI, OSF or GPT disklabel Building a new Dos disklabel. Changes will remain in memory only, until you decide to write them. After that the previous content won't be recoverable. The number of cylinders for this disk is set to 486192. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of Lilo)2) booting and partitioning software from other 0Ss (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): help 输入help提示 he unknown command 带助信息 Command Action a toggle a bootable flag edit bsd disklabel toggle the dos compatibility flag delete a partition list known partition types add a new partition create a new empty D0S partition table print the partition table quit without saving changes create a new empty Sun disklabel change a partition's system id change display/entry units verify the partition table write table to disk and exit extra functionality (experts only) Command (m for help): p 输入p打印分区表信息 Disk /dev/mmcblk0: 15 GB，15931539456 bytes, 31116288 sectors 486192 cylinders, 4 heads, 16 sectors/track Units: cylinders of 64 * 512 = 32768 bytes
可以看到我这张SD卡的相关信息，总容量为15931539456字节，31116288个sectors，即一个sector为512字节。
创建第一个分区
Command (m for help):n Command action extended e p primary partition (1-4) Partition number (1-4):1 First cylinder (1-486192,default 1):32 Last cylinder or +size or +sizeM or +sizeK (32-486192,default 486192):2080 Command (m for help): p Disk/dev/mmcblk0: 15 GB, 15931539456 bvtes, 31116288 sectors486192 cylinders, 4 heads, 16 sectors/track Units: cylinders of 64 * 512 = 32768 bytes Device Boot StartCHS EndCHS StartLBA EndLBA Sectors Size Id Type /dev/mmcblk0p1 31,0,1 1023,3,16 1984 133119 131136 64.0M 83 Linux Command (m for help): 0
输入n，添加一个新分区，这里提示输入分区号，范围1 ~ 4. 然后输入1，提示我们选择第一个柱面（一个柱面的大小是32KB）。 这里我选择32 ~（32+2048）作为第一个分区作boot分区（用来烧写dtb和kernel分区）。即32KB * 2048 = 64M大小。之所以从32开始，是把前1M（32K*32=1M）空间留给uboot，uboot是裸分区。
创建第二个分区
Command (m for help): n Command action e extended p primary partition (1-4) Partition number (1-4):2 First cvlinder (1-486192，default 1): 2081 Last cylinder or +size or +sizeM or +sizek (2081-486192, default 486192):486192 Command (m for help): p Disk/dev/mmcblk0: 15 GB，15931539456 bytes, 31116288 sectors486192 cylinders, 4 heads, 16 sectors/track Units: cylinders of 64 * 512 = 32768 bytes Device Boot StartCHS EndCHS StartLBA EndLBA Sectors Size Id Type /dev/mmcblk0p1 31,日,1 1023,3,16 1984 133119 131136 64.0M 83 Linux /dev/mmcblk0p2 1023,3,16 1023,3,16 133120 31116287 30983168 14.7G 83 Linux Command (m for help): 1
同样地，创建第二个分区，从2081~486192都划分给第二个分区。 以下是我设置的分区。
| 分区名 | 分区号 | 大小 |
| boot | 1 | 64M |
| 文件系统分区 | 2 | 剩余空间 |
设置p1为boot分区
Command (m for help): m Command Action a toggle a bootable flag b edit bsd disklabel toggle the dos compatibility flag delete a partition list known partition types add a new partition create a new empty Dos partition table print the partition table quit without saving changes create a new empty Sun disklabel change a partition's system id change display/entry units verify the partition table W write table to disk and exit X extra functionality (experts only) Command (m for help): t Partition number (1-4):1
Hex code (type list codes): 日 Empty 1b Hidden Win95 FAT32 9f BSD/0S FAT12 1c Hidden W95 FAT32 (LBA) a0 Thinkpad hibernation 4 FAT16 <32M le Hidden W95 FAT16 (LBA) a5 FreeBSD 5 Extended 3c Part.Magic recovery a6 0penBSD 6 FAT16 41 PPC PReP Boot a8 Darwin UFS 7 HPFS/NTFS 42 SFS a9 NetBSD a 0S/2 Boot Manager 63 GNU HURD or SysV ab Darwin boot b Win95 FAT32 80 0ld Minix b7 BSDI fs Win95FAT32(LBA) 81 Minix / old Linux b8 BSDI swap e Win95 FAT16 (LBA) 82 Linux swap be Solaris boot f Win95 Ext'd(LBA) 83 Linux eb BeOS fs 11 Hidden FAT12 84 0S/2 hidden C: drive ee EFI GPT 12 Compag diagnostics 85 Linux extended ef EFI (FAT-12/16/32) 14 Hidden FAT16 <32M 86 NTFS volume set f0 Linux/PA-RISC boot 16 Hidden FAT16 87 NTFS volume set f2 DOS secondary 17 Hidden HPES/NTES 8e Linux LVM fd Linux raid autodetect Hex code (type L to list codes): c Changed system type of partition 1 to c (Win95 FAT32 (LBA)
Command (m for help): m Command Action toggle a bootable flag edit bsd disklabel toggle the dos compatibility flag delete a partition list known partition types n add a new partition create a new empty D0S partition table print the partition table quit without saving changes S create a new empty Sun disklabel change a partition's system id change display/entry units U verify the partition table write table to disk and exit extra functionality (experts only) Command (m for help): a Partition number (1-4):1
使用t选项，选择第一个分区，然后选择c，把分区system id类型设置为fat。然后使用a，选择第一个分区为boot类型。
Command (m for help): p Disk/dev/mmcblk0: 15 GB，15931539456 bytes, 31116288 sectors486192 cylinders, 4 heads, 16 sectors/track Units: cylinders of 64 * 512 = 32768 bytes Device/dev/mmcblk0p1 Boot31,日,1 StartCHS EndCHS1023,3,16 StartLBA1984133119 EndLBA Secto1311 Size Id Type哆哆的Lnux存储杂记 /dev/mmcblk0p2 1023,3,16 1023,3,16 13312日 31116287 30983168 14.7G 83 Linux
可以看到p1后面boot那列多了个*。
格式化p1 p2
创建完分区之后，还需要对分区进行格式化。把p1的fstype格式化为fat，p2的fstype格式化为ext3分区。mke2fs可以用-t选项指定为ext3或者ext4。
mkfs.vfat -F 32 -n "boot" /dev/mmcblk0p1 mke2fs -t ext4 -F -L "rootfs" /dev/mmcblk0p2
烧录uboot.imx
dd if=u-boot.imx of=/dev/mmcblk0 bs=1024 seek=1 conv=fsync
通过dd命令烧录uboot.imx到SD卡。这里需要使用seek跳过前1K，这个跟这款芯片有关。
做到这一步，已经可以从SD启动u-boot了，不过里面还没有kernel和根文件系统。
烧录kernel
mkdir -p /tmp/kernel mount /dev/mmcblk0p1 /tmp/kernel cp -r /mnt/dfos.dtb /tmp/kernel cp -r /mnt/zImage /tmp/kernel umount /tmp/kernel
烧录根文件系统
mkdir -p /tmp/rootfs mount /dev/mmcblk0p2 /tmp/rootfs tar -vxf /mnt/rootfs.tar.bz2 -C /tmp/rootfs/ umount /tmp/rootfs
至此，就可以从SD卡启动系统了。
关于根文件系统打包
压缩
sudo tar -cvzf rootfs.tar.gz * sudo tar -cvjf rootfs.tar.bz2 *
解压
tar -vxf /mnt/rootfs.tar.gz -C /tmp/rootfs/ --strip-components 1 tar -vxf /mnt/rootfs.tar.bz2 -C /tmp/rootfs/
做成shell脚本一键烧录
使用方法：sd_burn.sh /dev/mmcblk0
#!/bin/sh #execute执行语句成功与否打印 execute () { $* >/dev/null if [ $? -ne 0 ]; then echo echo "错误: 执行 $*" echo exit 1 fi } device=$1 dfos_dtb=imx6ull-14x14-evk.dtb uboot='u-boot.imx' rootfs_img=rootfs.tar.bz2 #rootfs_img=rootfs.tar.gz #执行格式化$device execute "dd if=/dev/zero of=$device bs=1024 count=1024" #cat << END | fdisk -H 255 -S 63 $device cat << END | fdisk $device n p 1 32 2080 n p 2 2081 486192 t 1 c a 1 w END PARTITION1=${device}p1 PARTITION2=${device}p2 #第一个分区创建为Fat32格式 echo "格式化${device}p1 ..." if [ -b ${PARTITION1} ]; then echo "${PARTITION1} ..." mkfs.vfat -F 32 -n "boot" /dev/mmcblk0p1 else echo "error: no ${PARTITION1}" fi #第二个分区创建为ext4格式 echo "格式化${device}p2 ..." if [ -b ${PARITION2} ]; then echo "${PARTITION2} ..." /mnt/mke2fs -F -L "rootfs" /dev/mmcblk0p2 else echo "错误: /dev下找不到 SD卡 rootfs分区" fi echo "正在烧写${Uboot}到${device}" execute "dd if=/mnt/${uboot} of=$device bs=1024 seek=1 conv=fsync" sync echo "烧写${Uboot}到${device}完成！" echo "正在准备复制..." echo "正在复制设备树与内核到${PARTITION1}，请稍候..." execute "mkdir -p /tmp/kernel" execute "mount ${PARTITION1} /tmp/kernel" execute "cp -r /mnt/${dfos_dtb} /tmp/kernel" execute "cp -r /mnt/zImage /tmp/kernel" sync echo "复制设备树与内核到${device}p1完成！" echo "卸载${PARTITION1}" execute "umount /tmp/kernel" sleep 1 #解压文件系统到文件系统分区 #挂载文件系统分区 execute "mkdir -p /tmp/rootfs" execute "mount ${PARTITION2} /tmp/rootfs" echo "正在解压文件系统到${PARTITION2} ，请稍候..." #execute "tar -vxf /mnt/${rootfs_img} -C /tmp/rootfs/ --strip-components 1" execute "tar -vxf /mnt/${rootfs_img} -C /tmp/rootfs/" sync echo "解压文件系统到${PARTITION2}完成！" echo "卸载${PARTITION2}" execute "umount /tmp/rootfs" execute "rm -rf /tmp/rootfs" sync echo "SD卡启动系统烧写完成！"
号主：一枚机械专业本科生，经历了转行，从外包逆袭到芯片原厂的Linux驱动开发工程师，深入操作系统的世界，贯彻终身学习、终身成长的理念。平时喜欢折腾，寒冬之下，抱团取暖，期待你来一起探讨技术、搞自媒体副业，程序员接单和投资理财。【对了，不定期送闲置开发板、书籍、键盘等等】。
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