yocto uboot编译分析（基于stm32mp1）

环境介绍

软件环境：
repo init -u https://github.com/STMicroelectronics/oe-manifest.git -b refs/tags/openstlinux-5.10-dunfell-mp1-21-11-17
相关代码路径：
layers/meta-st/meta-st-stm32mp/recipes-bsp/u-boot

编译流程分析

总览

如上图所示，编译的入口是layers/meta-st/meta-st-stm32mp/recipes-bsp/u-boot/u-boot-stm32mp_2020.10.bb 文件
先浏览一下u-boot-stm32mp_2020.10.bb大致内容：

require u-boot-stm32mp-common_${PV}.inc
require u-boot-stm32mp.incSUMMARY = "Universal Boot Loader for embedded devices for stm32mp"
LICENSE = "GPLv2+"PROVIDES += "u-boot"
RPROVIDES_${PN} += "u-boot"# ---------------------------------
# Configure archiver use
# ---------------------------------
include ${@oe.utils.ifelse(d.getVar('ST_ARCHIVER_ENABLE') == '1', 'u-boot-stm32mp-archiver.inc','')}

可以看到实际上除了包含三个引用文件以外只提供了一个PROVIDES。而且其实在machine的st-machine-providers-stm32mp.inc 配置里面也有如下配置：

PREFERRED_PROVIDER_virtual/bootloader = "u-boot-stm32mp"
PREFERRED_PROVIDER_u-boot = "u-boot-stm32mp"

所以我们可以使用如下三个个命令编译uboot都是可以的：

bitbake u-boot-stm32mp
bitbake u-boot
bitbake virtual/bootloader

详细编译流程

所以uboot编译的重点就是上面说到的三个引用文件：
u-boot-stm32mp-common_${PV}.inc
u-boot-stm32mp.inc
u-boot-stm32mp-archiver.inc
其实还有一个machine conf里面的配置文件：st-machine-common-stm32mp.inc

1. st-machine-common-stm32mp.inc
   首先我们先看下st-machine-common-stm32mp.inc里面涉及到uboot比较重要的配置内容：（整理以后）

• UBOOT_CONFIG = trusted_stm32mp15 basic_stm32mp15
• UBOOT_CONFIG[basic_stm32mp15]= “stm32mp15_basic_defconfig,u-boot.img”
• UBOOT_CONFIG[trusted_stm32mp15] = “stm32mp15_trusted_defconfig,u-boot.stm32”
• UBOOT_DEVICETREE = “${STM32MP_DEVICETREE}”
• ST_UBOOT_DEBUG_TRACE=1

可以看到最主要的就是指定uboot配置和编译过程中使用的config文件和dts文件，以及调试符号表使能开关

2. u-boot-stm32mp-common_${PV}.inc
   本文件相对比较简单，主要就是设置菜谱的一些属性，包括：

• DEPENDS: 指定依赖
• SRC_URI : 指定源和patch
• SRCREV : 指定特定的节点
• PV : 指定版本号
• S : 指定源码路径

3. u-boot-stm32mp.inc
   该文件引入了标准的uboot编译指导文件require recipes-bsp/u-boot/u-boot.inc，然后在此基础上定制了几个func，下面简单介绍下这几个func的功能，具体内容可以看源码：

• do_configure_prepend
  如果配置生成的镜像文件是.stm32后缀，则向config文件中追加 CONFIG_STM32MP15x_STM32IMAGE=y 配置项
• do_configure_append
  检查是否支持nor nand启动，如果支持则在配置以后生成的.config文件中追加分区相关的配置信息，我支持sdcard和emmc启动，故本func没有做任何处理
• do_compile_append
  因为ST适配多芯片多评估板，所以他的STM32MP_DEVICETREE 变量会配置比较多，在uboot编译完成以后会继续检查STM32MP_DEVICETREE变量，会继续编译出STM32MP_DEVICETREE变量里面的dtb文件和镜像文件
• do_deploy_append
  部署会根据你的UBOOT_CONFIG UBOOT_DEVICETREE两个变量来决定上一步do_compile_append 编译出来的那么多dtb和bin文件到底安装哪几个到实际的image下

5. u-boot-stm32mp-archiver.inc

u-boot-stm32mp-archiver.inc实际上就是根据上面的配置生成一个Makefile.sdk文件，合并后的文件详细内容如下所示：

# Set default path
SRC_PATH ?= $(PWD)
BLD_PATH ?= $(SRC_PATH)/../build
DEPLOYDIR ?= $(SRC_PATH)/../deploy# Remove default variables
LDFLAGS =
CFLAGS =
CPPFLAGS =UBOOT_LOCALVERSION = # Configure default U-Boot configs
UBOOT_CONFIGS ?=  stm32mp15_trusted_defconfig,trusted,u-boot.dtb stm32mp15_basic_defconfig,basic,u-boot.img
DEVICE_TREE ?=   stm32mp157a-dk1 stm32mp157d-dk1 stm32mp157c-dk2 stm32mp157f-dk2   stm32mp157c-ed1 stm32mp157f-ed1   stm32mp157a-ev1 stm32mp157c-ev1 stm32mp157d-ev1 stm32mp157f-ev1 # Configure default fip feature
ENABLE_FIP ?= "1"help:@echo@echo "Configured U-Boot config(s):"@for config in $(UBOOT_CONFIGS); do \defconfig=$$(echo $$config | cut -d',' -f1) ; \type=$$(echo $$config | cut -d',' -f2) ; \binary=$$(echo $$config | cut -d',' -f3) ; \echo "  $$defconfig config ($$type type) for $$binary binary" ; \for devicetree in $(DEVICE_TREE); do \echo "    with device tree: $$devicetree" ; \done ; \done@echo@echo "U-Boot folder configuration:"@echo "  SRC_PATH  = $(SRC_PATH)"@echo "  BLD_PATH  = $(BLD_PATH)"@echo "  DEPLOYDIR = $(DEPLOYDIR)"@echo@echo "FIP configuration:"@echo "  ENABLE_FIP = $(ENABLE_FIP) ('1' to generate fip binary)"
ifeq ($(ENABLE_FIP),1)@echo "  Do not forget to set FIP deploydir folders (such as FIP_DEPLOYDIR_ROOT) to provide path to needed binaries"
endif@echo@echo "Available targets:"@echo "  all   : build U-Boot binaries for defined config(s)"@echo "  clean : clean build directories from generated files"version:@if test ! -e .scmversion ; then echo $(UBOOT_LOCALVERSION) > $(SRC_PATH)/.scmversion; fiall: uboot $(if $(ENABLE_FIP),fip)uboot: version@for config in $(UBOOT_CONFIGS); do \uboot_config=$$(echo $$config | cut -d',' -f1) ; \uboot_type=$$(echo $$config | cut -d',' -f2) ; \uboot_binary=$$(echo $$config | cut -d',' -f3) ; \uboot_suffix=$$(echo $$uboot_binary | cut -d'.' -f2) ; \# Configure destination folder \if [ "$$uboot_suffix" = "img" ]; then \subfolder=/$$uboot_type ; \else \subfolder= ; \fi ; \mkdir -p $(DEPLOYDIR)$$subfolder ; \mkdir -p $(DEPLOYDIR)$$subfolder/debug ; \# Make sure about configuration set \if test -z "$$uboot_config" -o -z "$$uboot_type" -o -z "$$uboot_binary"; then \echo ; \echo "[ERROR] UBOOT_CONFIGS wrongly configured. It should be space separated list of element ,," ; \echo ; \exit 1 ; \fi ; \# Dynamic update for defconfig file \if [ "$$uboot_suffix" = "stm32" ]; then \if ! grep -q 'CONFIG_STM32MP15x_STM32IMAGE=y' "$(SRC_PATH)/configs/$$uboot_config"; then \echo "CONFIG_STM32MP15x_STM32IMAGE=y" >> "$(SRC_PATH)/configs/$$uboot_config" ; \fi ; \fi ; \# Init folder and defconfig selected \if [ ! -d $(BLD_PATH)/$$uboot_type ]; then \mkdir -p $(BLD_PATH)/$$uboot_type ; \echo $(UBOOT_LOCALVERSION) > $(BLD_PATH)/$$uboot_type/.scmversion ; \$(MAKE) -C $(SRC_PATH) O=$(BLD_PATH)/$$uboot_type $$uboot_config ; \fi ; \# Build binaries \if [ -z "$(DEVICE_TREE)" ]; then \$(MAKE) -C $(SRC_PATH) O=$(BLD_PATH)/$$uboot_type all ; \# Copy binary files with explicit name \cp -f $(BLD_PATH)/$$uboot_type/$$uboot_binary $(DEPLOYDIR)$$subfolder/u-boot-$$uboot_type.$$uboot_suffix ; \if [ -f $(BLD_PATH)/$$uboot_type/spl/u-boot-spl.stm32 ]; then \cp -f $(BLD_PATH)/$$uboot_type/spl/u-boot-spl.stm32 $(DEPLOYDIR)$$subfolder/u-boot-spl.stm32-$$uboot_type ; \fi ; \if [ -f $(BLD_PATH)/$$uboot_type/u-boot ]; then \cp -f $(BLD_PATH)/$$uboot_type/u-boot $(DEPLOYDIR)$$subfolder/debug/u-boot-$$uboot_type.elf ; \fi ; \if [ -f $(BLD_PATH)/$$uboot_type/spl/u-boot-spl ]; then \cp -f $(BLD_PATH)/$$uboot_type/spl/u-boot-spl $(DEPLOYDIR)$$subfolder/debug/u-boot-spl.elf-$$uboot_type ; \fi ; \# Install 'u-boot-nodtb.bin' binary in case '*.dtb' binary installation configured \if [ "$$uboot_suffix" = "dtb" ]; then \cp -f $(BLD_PATH)/$$uboot_type/u-boot-nodtb.bin $(DEPLOYDIR)$$subfolder/u-boot-nodtb.bin ; \fi ; \else \for devicetree in $(DEVICE_TREE); do \$(MAKE) -C $(SRC_PATH) O=$(BLD_PATH)/$$uboot_type all DEVICE_TREE=$$devicetree DEVICE_TREE_EXT=$$devicetree.dtb; \# Copy binary files with explicit name \cp -f $(BLD_PATH)/$$uboot_type/$$uboot_binary $(DEPLOYDIR)$$subfolder/u-boot-$$devicetree-$$uboot_type.$$uboot_suffix ; \if [ -f $(BLD_PATH)/$$uboot_type/spl/u-boot-spl.stm32 ]; then \cp -f $(BLD_PATH)/$$uboot_type/spl/u-boot-spl.stm32 $(DEPLOYDIR)$$subfolder/u-boot-spl.stm32-$$devicetree-$$uboot_type ; \fi ; \if [ -f $(BLD_PATH)/$$uboot_type/u-boot ]; then \cp -f $(BLD_PATH)/$$uboot_type/u-boot $(DEPLOYDIR)$$subfolder/debug/u-boot-$$devicetree-$$uboot_type.elf ; \fi ; \if [ -f $(BLD_PATH)/$$uboot_type/spl/u-boot-spl ]; then \cp -f $(BLD_PATH)/$$uboot_type/spl/u-boot-spl $(DEPLOYDIR)$$subfolder/debug/u-boot-spl.elf-$$devicetree-$$uboot_type ; \fi ; \# Install ''u-boot-nodtb.bin' binary in case '*.dtb' binary installation configured \if [ "$$uboot_suffix" = "dtb" ]; then \# Init soc suffix \soc_suffix="" ; \if [ -n "stm32mp15" ]; then \for soc in stm32mp15; do \if [ "$$(echo $$devicetree | grep -c $$soc)" -eq 1 ]; then \soc_suffix="-$$soc" ; \fi ; \done ; \fi ; \cp -f $(BLD_PATH)/$$uboot_type/u-boot-nodtb.bin $(DEPLOYDIR)$$subfolder/u-boot-nodtb$$soc_suffix.bin ; \fi ; \done ; \fi ; \donefip: ubootFIP_DEPLOYDIR_UBOOT=$(DEPLOYDIR) FIP_DEVICETREE="$(DEVICE_TREE)" fiptool-stm32mpclean:@for config in $(UBOOT_CONFIGS); do \uboot_type=$$(echo $$config | cut -d',' -f2) ; \echo "Removing $(BLD_PATH)/$$uboot_type ..." ; \rm -rf $(BLD_PATH)/$$uboot_type ; \done@echo "Removing $(DEPLOYDIR) ..."@rm -rf $(DEPLOYDIR)@echo