MT7688 使用 u-boot-2021.01

mt7688 官方的 u-boot 太老太旧，主线 u-boot 似乎已经支持 mt7688 了。

见：https://github.com/u-boot/u-boot/commit/b02f76a83541fe9fe3a2918039b26fc133699c17

下载 u-boot-2021.01 https://sources.openwrt.org/u-boot-2021.01.tar.bz2

编译

解压：

tar xf u-boot-2021.01.tar.bz2
cd u-boot-2021.01

编译：

make linkit-smart-7688_defconfig
make ARCH=mips CROSS_COMPILE=/home/lql/work/openwrt/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_glibc/bin/mipsel-openwrt-linux-  -j5

问题1.哪个是可以烧到spi nor flash 上的文件？

经过测试， u-boot-with-spl.bin 是可以烧到spi nor flash 上的文件

问题2.如何修改 debug 串口？

dts 需要修改

xx_defconfig 需要修改

CONFIG_SPECIFY_CONSOLE_INDEX=y
CONFIG_CONS_INDEX=1                  // 1 表示 uart0

注意：新版 u-boot 串口波特率默认是 115200

问题3.reset 命令卡死？

可能原因：32M flash 有 4字节地址模式和3字节地址模式, 复位时如果没有从 4B 模式切回 3B 模式，就会出问题。

解决办法：CONFIG_SPI_FLASH_BAR=y 强制使用 3B 模式。

问题4.没有默认启动命令？

u-boot-2021.01 里面 mt7688 的默认env 里没有定义 bootcmd ，需要手动添加。

//board/seeed/linkit-smart-7688/Kconfigif BOARD_LINKIT_SMART_7688config SYS_BOARDdefault "linkit-smart-7688"config SYS_VENDORdefault "seeed"config SYS_CONFIG_NAMEdefault "linkit-smart-7688"                              -------------------------------------------------------o|
endif                                                                                                                   ||
---------------------------------------------------------------------------------------------                           |     |include/config.h  这个是自动生成的                                                    |/* Automatically generated - do not edit */                                         |#define CONFIG_BOARDDIR board/seeed/linkit-smart-7688                              |#include <config_uncmd_spl.h>                                                      |#include <configs/linkit-smart-7688.h>    <----------------------------------------o#include <asm/config.h>#include <linux/kconfig.h>#include <config_fallbacks.h>
-----------------------------------------------------------------------------------------
#include <common.h>                        // 里面 #include <config.h>
#include <bootstage.h>
#include <command.h>
#include <env.h>
#include <env_internal.h>
#include <log.h>
#include <sort.h>
#include <linux/stddef.h>
#include <search.h>
#include <errno.h>
#include <malloc.h>
#include <u-boot/crc.h>DECLARE_GLOBAL_DATA_PTR;/************************************************************************* Default settings to be used when no valid environment is found*/
#include <env_default.h>                   // Z:\opt\u-boot-2017.11.git\include\env_default.h
env_set_default   // Z:\opt\u-boot-2021.01\env\common.c

核心是添加 CONFIG_EXTRA_ENV_SETTINGS

问题5. OpenWrt 下编译u-boot 的各种问题

Q1: Build error: undefined reference to `pthread_once’

解决办法：修改 u-boot Makefile 加上 -pthread

参考：https://forum.openwrt.org/t/undefined-reference-to-pthread-once/65789/3

Q2:FATAL ERROR: Unrecognized check name “avoid_unnecessary_addr_size”

解决办法：修改 u-boot scripts/Makefile.lib ，用试错法兼容旧 dtc

    解决 openwrt 中编译 u-boot 报错 FATAL ERROR: Unrecognized check name "avoid_unnecessary_addr_size"diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index dfb6722..a7eda10 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -175,6 +175,11 @@ ld-version = $(shell $(LD) --version | $(srctree)/scripts/ld-version.sh)# Usage:  $(call ld-ifversion, -ge, 22252, y)ld-ifversion = $(shell [ $(ld-version) $(1) $(2) ] && echo $(3) || echo $(4))+# dtc-option
+# Usage:  DTC_FLAGS += $(call dtc-option,-Wno-unit_address_vs_reg)
+dtc-option = $(call try-run,\
+       echo '/dts-v1/; / {};' | $(DTC) $(1),$(1),$(2))
+#########
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 56e9d54..1697bc0 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -272,14 +272,16 @@ cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -n -f -9 > $@) || \# Disable noisy checks by defaultifeq ($(findstring 1,$(KBUILD_ENABLE_EXTRA_GCC_CHECKS)),)DTC_FLAGS += -Wno-unit_address_vs_reg \
-       -Wno-unit_address_format \
-       -Wno-avoid_unnecessary_addr_size \
-       -Wno-alias_paths \
-       -Wno-graph_child_address \
-       -Wno-graph_port \
-       -Wno-unique_unit_address \
-       -Wno-simple_bus_reg \
-       -Wno-pci_device_reg
+       -Wno-unit_address_format
+
+
+DTC_FLAGS += $(call dtc-option,-Wno-avoid_unnecessary_addr_size)
+DTC_FLAGS += $(call dtc-option,-Wno-alias_paths)
+DTC_FLAGS += $(call dtc-option,-Wno-graph_child_address)
+DTC_FLAGS += $(call dtc-option,-Wno-graph_port)
+DTC_FLAGS += $(call dtc-option,-Wno-unique_unit_address)
+DTC_FLAGS += $(call dtc-option,-Wno-simple_bus_reg)
+DTC_FLAGS += $(call dtc-option,-Wno-pci_device_reg)

参考：https://forum.openwrt.org/t/uboot-builds-failure-with-2020-01-for-openwrt-18-06/56009

Q3.LZMA u-boot.bin.lzma Error: Incorrect command

解决办法：修改 u-boot Makefile

--- a/Makefile
+++ b/Makefile
@@ -1009,7 +1009,7 @@ quiet_cmd_pad_cat = CAT     $@cmd_pad_cat = $(cmd_objcopy) && $(append) || rm -f $@quiet_cmd_lzma = LZMA    $@
-cmd_lzma = lzma -c -z -k -9 $< > $@
+cmd_lzma = xz -F lzma -c -z -k -9 $< > $@cfg: u-boot.cfg

说明：lzma = xz -F lzma