FIT介绍-1

1、编译

FIT image 文件的编译过程很简单，根据实际情况，编写image source file之后（假设名称为u-boot.its），在命令行使用mkimage工具编译即可：

./tools/mkimage [-D dtc_options] [-f fit-image.its|-f auto|-f auto-conf|-F] [-b <dtb> [-b <dtb>]] [-E] [-B size] [-i <ramdisk.cpio.gz>] fit-image<dtb> file is used with -f auto, it may occur multiple times.-D => set all options for device tree compiler-f => input filename for FIT source-i => input filename for ramdisk file-E => place data outside of the FIT structure-B => align size in hex for FIT structure and header-b => append the device tree binary to the FIT-t => update the timestamp in the FIT

其中：

-D：指定 DTC（Device Tree Compiler）编译器的选项；
-f ：指定需要编译的image source file，并在后面指定需要生成的image文件（一般以.itb为后缀，例如u-boot.itb）。
-i：指定用于创建 FIT 镜像的 RAM disk 文件名；
-E：将image data file放置在FIT结构外的选项；
-B：指定 FIT 结构和头的对齐大小；
-b：支持将一个或多个设备树二进制文件附加到 FIT 文件中（可使用 -b <dtb> 多次指定）;
-t：更新 FIT 文件中的时间戳;
其中-E这个字段比较重要，它会影响生成的itb的文件布局；
如果没有指定该选项，其生成的itb文件格式和dts文件编译生成的dtb文件布局一样，包括data属性指定的/incbin/("bl31_0x00040000.bin")文件也会以二进制数据格式的形式放到FIT结构内；
如果指定了该选项，会为data属性指向的文件扩充data-offset（指定文件的偏移，这个偏移是以FIT结构结束地址下一扇区起始地址开始计算的）、以及data-size（指定文件的大小）属性，而在data属性指向的二进制数据文件将会被追加到FIT结构的尾部（也是扇区对齐）；下面我们分析的itb文件布局格式就是这种；

因此我们可以采用如下方式生成u-boot.itb文件：

./tools/mkimage  -f  u-boot.its -E u-boot.itb

u-boot.itb生成后，也可以使用mkimage命令查看它的信息：

tools/mkimage -l u-boot.itb

2，源文件its

/dts-v1/;/ {description = "Configuration to load ATF before U-Boot";#address-cells = <1>;images {uboot {description = "U-Boot (64-bit)";data = /incbin/("u-boot-nodtb.bin");type = "standalone";os = "U-Boot";arch = "arm64";compression = "none";load = <0x00200000>;hash {algo = "sha256";};};atf@1 {description = "ARM Trusted Firmware";data = /incbin/("bl31_0x00040000.bin");type = "firmware";arch = "arm64";os = "arm-trusted-firmware";compression = "none";load = <0x00040000>;entry = <0x00040000>;hash {algo = "sha256";};};atf@2 {description = "ARM Trusted Firmware";data = /incbin/("bl31_0xff3b0000.bin");type = "firmware";arch = "arm64";os = "arm-trusted-firmware";compression = "none";load = <0xff3b0000>;hash {algo = "sha256";};};atf@3 {description = "ARM Trusted Firmware";data = /incbin/("bl31_0xff8c0000.bin");type = "firmware";arch = "arm64";os = "arm-trusted-firmware";compression = "none";load = <0xff8c0000>;hash {algo = "sha256";};};atf@4 {description = "ARM Trusted Firmware";data = /incbin/("bl31_0xff8c1000.bin");type = "firmware";arch = "arm64";os = "arm-trusted-firmware";compression = "none";load = <0xff8c1000>;hash {algo = "sha256";};};atf@5 {description = "ARM Trusted Firmware";data = /incbin/("bl31_0xff8c2000.bin");type = "firmware";arch = "arm64";os = "arm-trusted-firmware";compression = "none";load = <0xff8c2000>;hash {algo = "sha256";};};fdt {description = "U-Boot device tree blob";data = /incbin/("u-boot.dtb");type = "flat_dt";arch = "arm64";compression = "none";hash {algo = "sha256";};};};configurations {default = "config";config {description = "Rockchip armv8 with ATF";rollback-index = <0x0>;firmware = "atf@1";loadables = "uboot", "atf@2" , "atf@3" , "atf@4" , "atf@5" , "atf@6" ;fdt = "fdt";signature {algo = "sha256,rsa2048";padding = "pss";key-name-hint = "dev";sign-images = "fdt", "firmware", "loadables";};};};};