问题解决：
需修改rtconfig.py编译参数

旧参数：

modified by rtthread.studio.vscode

DEVICE = ‘ -mcpu=cortex-m4 -mthumb -ffunction-sections -fdata-sections’
CFLAGS = DEVICE + ‘ -Dgcc’
CFLAGS += ‘ -O0 -gdwarf-2 -g’
CXXFLAGS = CFLAGS
AFLAGS = ‘ -c’ + DEVICE + ‘ -x assembler-with-cpp -Wa,-mimplicit-it=thumb ‘
AFLAGS += ‘ -gdwarf-2’
POST_ACTION = OBJCPY + ‘ -O binary $TARGET rtthread.bin\n’ + SIZE + ‘ $TARGET \n’

新参数：需增加 LFLAGS = DEVICE + ‘ -Wl,—gc-sections,-Map=rtthread.map,-cref,-u,Reset_Handler -T linkscripts//STM32F407VG//link.lds’

modified by rtthread.studio.vscode

DEVICE = ‘ -mcpu=cortex-m4 -mthumb -ffunction-sections -fdata-sections’
CFLAGS = DEVICE + ‘ -Dgcc’
CFLAGS += ‘ -O0 -gdwarf-2 -g’
CXXFLAGS = CFLAGS
AFLAGS = ‘ -c’ + DEVICE + ‘ -x assembler-with-cpp -Wa,-mimplicit-it=thumb ‘
LFLAGS = DEVICE + ‘ -Wl,—gc-sections,-Map=rtthread.map,-cref,-u,Reset_Handler -T linkscripts//STM32F407VG//link.lds’
AFLAGS += ‘ -gdwarf-2’
POST_ACTION = OBJCPY + ‘ -O binary $TARGET rtthread.bin\n’ + SIZE + ‘ —format=berkeley’ + ‘ $TARGET \n’

估计问题出在
arm-none-eabi-size --format=berkeley "rtthread.elf"
可能你的MCU目前只识别berkeley格式的二进制文件。

两个elf文件大小差那么多，检查一下两个项目编译的文件能不能对应的上，是不是两个项目参与编译的文件根本不一样