一、编译TF-A
1. 获取TF-A源码
下载链接：en.SOURCES-tf-a-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17_tar.xz。
下载后解压：
xz -d en.SOURCES-tf-a-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17_tar.xz
mv en.SOURCES-tf-a-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17_tar en.SOURCES-tf-a-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17.tar
tar -xvf en.SOURCES-tf-a-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17.tar
里面分为源码和patch文件：
tf-a-stm32mp-v2.4-stm32mp-r2-r0 TF-A installation directory
├── [*].patch ST patches to apply during the TF-A preparation (see next chapter)
├── tf-a-stm32mp-v2.4-stm32mp-r2 TF-A source code directory
├── Makefile.sdk Makefile for the TF-A compilation
├── README.HOW_TO.txt Helper file for TF-A management: reference for TF-A build
├── series List of all ST patches to apply
└── tf-a-stm32mp-v2.4-stm32mp-r2-r0.tar.gz Tarball file of the TF-A source code
除了uboot源码之外，在上一级目录下，还有 FIP_artifacts 目录如下：
FIP_artifacts
├── arm-trusted-firmware
│ ├── bl32
│ └── fwconfig
2. 编译TF-A
编译前的准备
（1）OpenSTLinux SDK 必须安装；
（2）编译内核需要安装的包：
llibncurses、libncursesw dev package、libyaml-dev：
sudo apt-get install libncurses5-dev libncursesw5-dev libyaml-dev
（3）确保SDK环境变量生效（注意路径）：
source $HOME/STM32MPU_workspace/STM32MP15-Ecosystem-v3.1.0/Developer-Package/SDK/environment-setup-cortexa7t2hf-neon-vfpv4-ostl-linux-gnueabi
接下来开始编译。
解压源码：
tar -zxvf tf-a-stm32mp-v2.4-stm32mp-r2-r0.tar.gz
源码打补丁：
cd tf-a-stm32mp-v2.4-stm32mp-r2/
for p in `ls -1 ../*.patch`; do patch -p1 < $p; done
因为在 OpenSTLinux 默认激活了 FIP，所以在编译前必须要指定FIP_artifacts：
export FIP_DEPLOYDIR_ROOT=$PWD/../../FIP_artifacts
编译全部：
make -f $PWD/../Makefile.sdk all
编译出的结果在上级目录的 deploy 文件夹：
3. 烧写测试
使用第一篇文章中烧写成功过的SD卡，只替换 FSBL 进行验证：
sudo dd if=tf-a-stm32mp157c-dk2-sdcard.stm32 of=/dev/sdb1 conv=fdatasync
sudo dd if=tf-a-stm32mp157c-dk2-sdcard.stm32 of=/dev/sdb2 conv=fdatasync
将SD卡重新插入STM32MP157C-DK2开发板，可以正常启动，查看串口日志，TF-A编译时间已修改：
二、编译uboot
1. 获取uboot源码（2020.10版本）
下载链接：en.SOURCES-u-boot-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17_tar.xz
下载后解压：
mv en.SOURCES-u-boot-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17_tar.xz en.SOURCES-u-boot-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17.tar.xz
tar -xvf en.SOURCES-u-boot-stm32mp1-openstlinux-5-10-dunfell-mp1-21-11-17.tar.xz
里面分为源码和patch文件：
u-boot-stm32mp-v2020.10-stm32mp-r2-r0 U-Boot installation directory
├── [*].patch ST patches to apply during the U-Boot preparation (see next chapter)
├── u-boot-stm32mp-v2020.10-stm32mp-r2 U-Boot source code directory
├── Makefile.sdk Makefile for the U-Boot compilation
├── README.HOW_TO.txt Helper file for U-Boot management: reference for U-Boot build
├── series List of all ST patches to apply
└── u-boot-stm32mp-v2020.10-stm32mp-r2-r0.tar.gz Tarball file of the U-Boot source code
解压源码：
tar -zxvf u-boot-stm32mp-v2020.10-stm32mp-r2-r0.tar.gz
除了uboot源码之外，在上一级目录下，还有 FIP_artifacts 目录如下：
FIP_artifacts
├── arm-trusted-firmware
│ ├── bl32
│ └── fwconfig
├── optee
├── u-boot
│ ├── u-boot-nodtb-stm32mp15.bin
│ ├── u-boot-stm32mp157a-dk1-trusted.dtb Device tree for U-Boot → STM32MP15 Discovery kits
│ ├── u-boot-stm32mp157a-ev1-trusted.dtb Device tree for U-Boot → STM32MP15 Evaluation boards
│ ├── u-boot-stm32mp157c-dk2-trusted.dtb Device tree for U-Boot → STM32MP15 Discovery kits
│ ├── u-boot-stm32mp157c-ed1-trusted.dtb Device tree for U-Boot → STM32MP15 Evaluation boards
│ ├── u-boot-stm32mp157c-ev1-trusted.dtb Device tree for U-Boot → STM32MP15 Evaluation boards
│ ├── u-boot-stm32mp157d-dk1-trusted.dtb Device tree for U-Boot → STM32MP15 Discovery kits
│ ├── u-boot-stm32mp157d-ev1-trusted.dtb Device tree for U-Boot → STM32MP15 Evaluation boards
│ ├── u-boot-stm32mp157f-dk2-trusted.dtb Device tree for U-Boot → STM32MP15 Discovery kits
│ ├── u-boot-stm32mp157f-ed1-trusted.dtb Device tree for U-Boot → STM32MP15 Evaluation boards
│ └── u-boot-stm32mp157f-ev1-trusted.dtb Device tree for U-Boot → STM32MP15 Evaluation boards
2. 编译uboot
2. 1. uboot源码打patch
cd u-boot-stm32mp-v2020.10-stm32mp-r2/
for p in `ls -1 ../*.patch`; do patch -p1 < $p; done
2.2. 编译uboot（带FIP）
指定FIP文件夹路径：
export FIP_DEPLOYDIR_ROOT=$PWD/../../FIP_artifacts
编译全部：
make -f $PWD/../Makefile.sdk all
编译出来之后，需要部署的文件在上一级目录 deploy 中：
同时，编译出的 FIP 文件在上一级目录FIP_artifacts中：
3. 烧写测试
使用第一篇文章中烧写成功过的SD卡，只替换 FIP 进行验证：
sudo dd if=fip-stm32mp157c-dk2-trusted.bin of=/dev/sdb3 conv=fdatasync
将SD卡重新插入STM32MP157C-DK2开发板，可以正常启动，查看串口日志，u-boot 编译时间已修改：
三、编译内核
1. 获取内核源码
下载链接：en.SOURCES-kernel-stm32mp1-openstlinux-5.10-dunfell-mp1-21-11-17.tar.xz
下载后解压：
tar xvf en.SOURCES-kernel-stm32mp1-openstlinux-5.10-dunfell-mp1-21-11-17.tar.xz
里面分为源码和patch文件：
linux-stm32mp-5.10.61-r2 Linux kernel installation directory
├── [*].patch ST patches to apply during the Linux kernel preparation (see next chapter)
├── fragment-[*].config ST configuration fragments to apply during the Linux kernel configuration (see next chapter)
├── linux-5.10.61 Linux kernel source code directory
├── linux-5.10.61.tar.xz Tarball file of the Linux kernel source code
├── README.HOW_TO.txt Helper file for Linux kernel management: reference for Linux kernel build
└── series List of all ST patches to apply
解压源码：
xz -d xvf linux-5.10.61.tar.xz
tar xvf linux-5.10.61.tar
2. 编译kernel
2.1. 编译前的准备
（1）OpenSTLinux SDK 必须安装；
（2）编译内核需要安装的包：
llibncurses、libncursesw dev package、libyaml-dev：
sudo apt-get install libncurses5-dev libncursesw5-dev libyaml-dev
mkimage：
sudo apt-get install u-boot-tools
yaml (check dts)：
sudo apt-get install libyaml-dev
（3）确保SDK环境变量生效：
source STM32MP15-Ecosystem-v3.1.0/Developer-Package/SDK/environment-setup-cortexa7t2hf-neon-vfpv4-ostl-linux-gnueabi
2.2. 内核源代码打patch
cd linux-5.10.61/
for p in `ls -1 ../*.patch`; do patch -p1 < $p; done
2.3. 源码配置
方式：配置编译目录 (different of kernel source code directory）
创建build目录：
mkdir -p ../build
生成默认配置文件.config：
make ARCH=arm O="$PWD/../build" multi_v7_defconfig fragment*.config
循环应用 fragment*.config 文件（搞不懂干啥的，执行了之后编译会出错，所以不要执行）：
for f in `ls -1 ../fragment*.config`; do scripts/kconfig/merge_config.sh -m -r -O $PWD/../build $PWD/../build/.config $f; done
yes '' | make ARCH=arm oldconfig
2.4. 编译源码
编译内核：
make ARCH=arm uImage vmlinux dtbs LOADADDR=0xC2000040 O="$PWD/../build"
编译完成：
编译完成之后，在上一级目录的build/arch/arm/boot目录下可以看到编译出的镜像：
在dts目录下可以看到编译出的设备树：
2.5. 编译模块
make ARCH=arm modules O="$PWD/../build"
3. 烧写
sdb4分区是ext4文件系统，所以将之前使用的SD卡插入后，需要将该文件系统挂载：
sudo mkdir -p /mnt/bootfs
sudo mount /dev/sdb4 /mnt/bootfs/
挂载后查看其中内容，存放了Linux内核镜像、设备树等：
进入到内核编译目录，将之前内核编译出的镜像和设备树拷贝替换：
sudo cp -f uImage /mnt/bootfs/
sudo cp -f dts/stm32mp157c-dk2.dtb /mnt/bootfs/
卸载文件系统：
sudo umount /dev/sdb4
重新将SD卡插入到开发板中，查看是否可以正常启动：
