如何在buildroot打包bootfs.ext4

贫穷贵公子 

在开发STM32MP157的时候，内核的uImage和stm32mp157d-atk.dtb设备树，会被打包成ext4格式的文件系统，然后通过uboot进行加载。本文介绍一种方法，通过buildroot的构建环境，生成uImage的同时，完成bootfs.ext4的打包。

配置buildroot时，以stm32mp157a_dk1_defconfig为基础，进行构建。

make stm32mp157a_dk1_defconfig

该配置会指定 post-image.sh 的后处理脚本，用于生成sdcard.img。

buildroot-2022.02/board/stmicroelectronics/common/stm32mp157/post-image.sh

通过在该脚本当中，增加逻辑，生成bootfs.img

diff --git a/buildroot-2022.02/board/stmicroelectronics/common/stm32mp157/post-image.sh b/buildroot-2022.02/board/stmicroelectronics/common/stm32mp157/post-image.sh
index 363c3127c..ee02f43b9 100755
--- a/buildroot-2022.02/board/stmicroelectronics/common/stm32mp157/post-image.sh
+++ b/buildroot-2022.02/board/stmicroelectronics/common/stm32mp157/post-image.sh
@@ -13,9 +13,11 @@ atf_image()
        if grep -Eq "DTB_FILE_NAME=stm32mp157c-dk2.dtb" <<< ${ATF_VARIABLES}; then
                echo "tf-a-stm32mp157c-dk2.stm32"
        elif grep -Eq "DTB_FILE_NAME=stm32mp157a-dk1.dtb" <<< ${ATF_VARIABLES}; then
-                echo "tf-a-stm32mp157a-dk1.stm32"
+        echo "tf-a-stm32mp157a-dk1.stm32"
        elif grep -Eq "DTB_FILE_NAME=stm32mp157a-avenger96.dtb" <<< ${ATF_VARIABLES}; then
-                echo "tf-a-stm32mp157a-avenger96.stm32"
+        echo "tf-a-stm32mp157a-avenger96.stm32"
+       elif grep -Eq "DTB_FILE_NAME=stm32mp157a-dk1.dtb" <<< ${ATF_VARIABLES}; then
+        echo "stm32mp157a-dk1.dtb"
@@ -32,7 +34,21 @@ main()
        rm -f ${GENIMAGE_CFG}
+       bootfs_img
        exit $?
+bootfs_img()
+       rm -rf ${BUILD_DIR}/genbootimage.tmp
+       mkdir -p ${BUILD_DIR}/genbootimage.tmp
+       local GENBOOTIMAGE_TMP="${BUILD_DIR}/genbootimage.tmp"
+       cp ${BUILD_DIR}/../images/uImage ${GENBOOTIMAGE_TMP}