代码参考https://github.com/colourfate/x210_bsp/

他的是linux_4.10(dtb为 s5pv210-x210..dtb)我打算用linux4.19.114(dtb为 s5pv210-smdkv210.dtb) ，所以修改build.sh

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    5 MFLAG="ARCH=arm CROSS_COMPILE=/home/rlk/Downloads/arm-linux-gnueabihf_6.5/bin/arm-linux-gnueabihf-"
    6 #MFLAG="ARCH=arm CROSS_COMPILE=$BASEPATH/toolchain/4.9.3/bin/arm-linux-"
    7 #MFLAG="ARCH=arm CROSS_COMPILE=arm-linux-"
    8 UBOOTDIR=u-boot-2017.09
    9 LINUXDIR=linux-4.19.114
   10 ROOTFSDIR=buildroot-2018.08

   12 # sd卡设备文件
   13 SDDEV=/dev/sdb
   14 BL1POS=1       # BL1从1扇区开始
   15 UBOOTPOS=49     # uboot从49扇区开始
   16 # sd卡挂载点
   SDDIR=/media/rlk/16930e10-5629-4824-9786-fdc160e6e9b2/
 

   20 if [ $# == 0 ]; then
   21     echo -e "\n------------------------uboot------------------------\n"
   22     cd $UBOOTDIR
   23     make x210_defconfig $MFLAG
   24     make $MFLAG
   25     cd sd_fusing/
   26     make
   27     ./mkx210 ../u-boot.bin 210.bin
   28     cd $BASEPATH
   29     cp $UBOOTDIR/u-boot.bin $UBOOTDIR/sd_fusing/210.bin outpu
   32     BOOTDIR=arch/arm/boot
   33     cd $LINUXDIR
   34     make s5pv210_defconfig $MFLAG
   35     rm $BOOTDIR/uImage
   36     make uImage s5pv210-smdkv210.dtb LOADADDR=0x30007FC0 $MFLAG
   37     cp $BOOTDIR/uImage $BOOTDIR/dts/s5pv210-smdkv210.dtb $BASEPATH/output
   38     cd $BASEPATH
   39 
   40     # FIXME: build root的工具链需要单独配置

   42     cd $ROOTFSDIR
   43     make x210_defconfig
   44     BR2_TOOLCHAIN_EXTERNAL_PATH=/home/rlk/Downloads/arm-linux-gnueabihf_6.5/bin/
   46     BR2_TOOLCHAIN_EXTERNAL_CUSTOM_PREFIX=arm-linux-gnueabihf-
   47     make ARCH=arm CROSS_COMPILE=/home/rlk/Downloads/arm-linux-gnueabihf_6.5/bin/arm-linux-gnueabihf-
   48     cp output/images/rootfs.tar $BASEPATH/output
   49     cd $BASEPATH

menuconfig截图：

如果buildroot最后生不出rootfs.rar可以不管直接去buildroot/output/target/拷贝到sd卡里的rootfs

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uboot启动后参数配置（对应s5pv210-smdkv210.dtb的配置为root=/dev/mmcblk2p1，很奇怪，这里mmcblk2，内核看到的mmc编号2与uboot看到不一样1；但是若用s5pv210-x210.dtb,则配置为root=/dev/mmcblk1p1)

x210#setenv bootargs "noinitrd console=ttySAC2,115200 root=/dev/mmcblk2p1 rw init=/linuxrc rootfstype=ext4"
x210#ext4load mmc 1:1 0x30007FC0 uImage;（在uboot来看sd卡为编号为1，uImage在1分区）

x210#ext4load mmc 1:1 0x30000000 s5pv210-smdkv210.dtb
x210#fdt addr 30000000 ;bootm 30007FC0 - 30000000

----------------------------------------------------------------------------

注意uboot环境变量：

bootargs=root=/dev/mtdblock8 rootfstype=ext4 ${console} ${meminfo} ${mtdparts}
bootblock=9
bootchart=set opts init=/sbin/bootchartd; run bootcmd
bootcmd=run mmcboot
bootk=run loaduimage;bootm 0x30007FC0
cpu=armv7
fdtfile=s5pc1xxc110-x210.dtb
flashboot=set bootargs root=/dev/mtdblock${bootblock} rootfstype=${rootfstype} ${opts} ${lcdinfo} ${console} ${meminfo} ${mtdparts}; run bootk
loaduimage=ext4load mmc ${mmcdev}:${mmcbootpart} 0x30007FC0 uImage
meminfo=mem=80M mem=256M@0x40000000 mem=128M@0x50000000
mmcboot=set bootargs root=/dev/mmcblk${mmcdev}p${mmcrootpart} rootfstype=${rootfstype} ${opts} ${lcdinfo} ${console} ${meminfo} ${mtdparts}; run bootk
mmcbootpart=1 //cbootpart我这里也放在1分区,里面有uImage,dtd
mmcdev=1  //在uboot来看sd卡为编号为1
mmcrootpart=1 //rootfs我这里也放在1分区

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sd卡内容$ ls
bin  etc  lib32    lost+found  mnt  proc  rootfs.tar  s5pv210-smdkv210.dtb  sbin  tmp     uImage_4.19  var dev  lib  linuxrc  media       opt  root  run         s5pv210-x210.dtb      sys   uImage  usr          zImage_4.19