[Mainline U-Boot & Mainline Kernel & Rootfs Howto]

Mainline U-Boot

# 克隆u-boot仓库
git clone git://git.denx.de/u-boot.git

# 编译配置
make orangepi_zero_defconfig

# 交叉编译
make V=s -j8 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-

编译完成在源码根目录出现目标文件：

u-boot-sunxi-with-spl.bin

Mainline Kernel

# 克隆kernel仓库
git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

# 编译配置
make ARCH=arm sunxi_defconfig

# 交叉编译
make V=s -j8 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-

编译完成在源码目录出现目标文件：

zImage (arch/arm/boot/zImage)
sun8i-h2-plus-orangepi-zero.dtb (arch/arm/boot/dts/sun8i-h2-plus-orangepi-zero.dtb)

Rootfs

1\ busybox

# 克隆busybox仓库
git clone git://git.busybox.net/busybox

# 编译配置
make menuconfig

[*] Build busybox as a static binary

(arm-linux-gnueabihf-) Cross Compiler prefix

(./_install) Busybox Installation prefix

# 编译
make

cd _install/

chmod 4755 bin/busybox

接下来的步骤都基于这个_install文件夹。

2\ etc/inittab

创建etc/inittab文件：

# /etc/inittab
::sysinit:/etc/init.d/rcS
ttyS0::sysinit:/bin/ash
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r

3\ etc/fstab

创建etc/fstab文件：

# device        mount-point     type    options dump    fsck    order
proc    /proc   proc    defaults        0       0
tmpfs   /tmp    tmpfs   defaults        0       0

4\ etc/init.d/rcS

创建etc/init.d/rcS文件：

#!/bin/sh
mount -a

5\ 创建设备节点

在dev目录下创建基本的设备节点：

mknod -m 0666 console c 5 1
mknod -m 0666 null c 1 3
mknod ttyS0 c 4 64

Install

将sd卡分区，第一个分区放zImage和dtb文件，第二个分区作为rootfs挂载：

#!/bin/sh

card=/dev/mmcblk0
cardroot=${card}${p}2

# sd卡格式化
dd if=/dev/zero of=${card} bs=1M count=1

# sd卡分区
blockdev --rereadpt ${card}
cat <<EOT | sfdisk ${card}
1M,16M,c
,,L
EOT

# 格式化分区
mkfs.vfat ${card}${p}1
mkfs.ext4 ${card}${p}2

# 刷入U-Boot
dd if=u-boot-sunxi-with-spl.bin of=${card} bs=1024 seek=8

# 写入zImage和dtb文件
mount ${card}${p}1 /mnt/
cp zImage /mnt/
cp sun8i-h2-plus-orangepi-zero.dtb /mnt/
umount /mnt/

# 写入rootfs
mount ${cardroot} /mnt/
cp -r /myrootfs /mnt/
umount /mnt

Boot

在U-Boot命令行中执行：

=> setenv bootargs 'console=ttyS0,115200n8 earlyprintk root=/dev/mmcblk0p1 rootwait panic=10'
=> fatload mmc 0 0x46000000 zImage
reading zImage
3657840 bytes read in 226 ms (15.4 MiB/s)
=> fatload mmc 0 0x49000000 sun8i-h2-plus-orangepi-zero.dtb
reading sun8i-h2-plus-orangepi-zero.dtb
14025 bytes read in 30 ms (456.1 KiB/s)
=> bootz 0x46000000 - 0x49000000

Boot Success

成功进入Linux系统，重新挂载可读写文件系统，挂载proc，sys，debug目录：

/ # mount -o remount,rw /
[   58.970790] EXT4-fs (mmcblk0p2): re-mounted. Opts: data=ordered
/ # mount -t proc proc /proc
/ # mount -t sysfs sysfs /sys
/ # mount -t debugfs debugfs /sys/kernel/debug

/ # cat /proc/version 
Linux version 4.11.0-rc4-00064-g89970a0 (chenziping@techping-pc) (gcc version 6.2.1 20161016 (Linaro GCC 6.2-2016.11) ) #1 SMP Thu Mar 30 18:55:45 CST 2017
/ #