scons 搭建嵌入式arm编译

最近发现scons真的很好用，python语法比makefile友好很多。准备用scons 替换掉项目中的makefile，重新搭建build system。

本文是之前自己刚开始学习scons的一个小demo，用来编译一个嵌入式arm的项目。

DEMO源码

项目目录

-scons_demo
	- boot.s
	- cm4.ld
	- compiler.py
	- main.c
	- SConstruct
	- driver
		- SConscript 
		- qemu_print.c
		- sub_driver
			- Sconscript
			- sub_driver.c

• 一共有三个目录，根目录scons_demo, driver, sub_driver.
• 四个源文件 boot.s, main.c, driver/qemu_print.c, driver/sub_driver/test.c
• 一个链接文件cm4.ld。

编译目标

1. 将四个源文件编译成*.o
2. 然后根据cm4.ld 将obj文件输出elf
3. 根据elf输出binary文件，同时导出反汇编文件。

compiler.py：定义编译器、编译参数和链接参数

COMPILER_PREFIX = 'arm-none-eabi-'
DEF_LINK = COMPILER_PREFIX + 'ld'
DEF_AS = COMPILER_PREFIX + 'as'
DEF_GCC = COMPILER_PREFIX + 'gcc'
DEF_OBJCOPY = COMPILER_PREFIX + 'objcopy'
DEF_LINKFLAGS = '-T cm4.ld'

DEF_CFLAGS = [
       '-std=c11', 
       '-g', 
       '-mcpu=cortex-m3', 
       '-mthumb', 
       '-nostartfiles',  
       '--specs=nosys.specs'
        ]

scons_demo/SConsturct

import os
# 导入编译参数
from compiler import *

# 创建编译环境，使用complier.py中的编译器以及编译参数、链接参数
env = Environment()
env['LINK'] = DEF_LINK
env['AS'] = DEF_AS
env['CC'] = DEF_GCC
env['OBJCOPY'] = DEF_OBJCOPY
env['LINKFLAGS'] = DEF_LINKFLAGS
env.Append(CCFLAGS = DEF_CFLAGS)

#指定子目录，这里只有一个子目录driver
sub_dirs = [
        'driver'
        ]
#编译当前目录下所有c文件到o文件
env.Object(Glob('*.c'))
#编译当前目录下boot.s到o文件
env.Object('boot.s')

src_obj = Glob('*.o')
#遍历添加子目录中的.o文件
for d in sub_dirs:
    src_obj += SConscript(d + '/SConscript')

#将所有的.o根据cm4_ld链接成main.elf
env.Program('main.elf', src_obj)
#根据elf生成binary
env.Command('main.bin', 'main.elf', env['OBJCOPY'] + ' -O binary -S -R .note -R .comment main.elf main.bin')
#根据elf生成反汇编
env.Command('main.dis', 'main.elf', 'arm-none-eabi-objdump -S main.elf > main.dis')

scons_demo/driver/SConscript

# 导入编译参数
from compiler import *
#指定子目录，这里只有一个子目录sub_driver
sub_dirs = [
        'sub_driver'
        ]

env = Environment()
env['LINK'] = DEF_LINK
env['AS'] = DEF_AS
env['CC'] = DEF_GCC
env['OBJCOPY'] = DEF_OBJCOPY
env['LINKFLAGS'] = DEF_LINKFLAGS
env.Append(CCFLAGS = DEF_CFLAGS)
#编译所有c文件到o文件
src = Glob('*.c')
obj = env.Object(src)
src_obj = Glob('*.o')
#遍历添加子目录中的.o文件
for d in sub_dirs:
    obj = obj + SConscript(d + '/SConscript')
#返回obj文件给上级目录scons_demo/SConstruct
Return('obj')

scons_demo/driver/sub_driver/SConscript

# 导入编译参数
from compiler import *

env = Environment()
env['LINK'] = DEF_LINK
env['AS'] = DEF_AS
env['CC'] = DEF_GCC
env['OBJCOPY'] = DEF_OBJCOPY
env['LINKFLAGS'] = DEF_LINKFLAGS
env.Append(CCFLAGS = DEF_CFLAGS)
#编译所有c文件到o文件
src = Glob('*.c')
obj = env.Object(src)
#返回obj文件给上级目录scons_demo/driver/SConsript
Return('obj')

编译log

~/Misc_demo/scons_demo$ scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
arm-none-eabi-as -o boot.o boot.s
arm-none-eabi-gcc -o driver/qemu_print.o -c -std=c11 -g -mcpu=cortex-m3 -mthumb -nostartfiles --specs=nosys.specs driver/qemu_print.c
arm-none-eabi-gcc -o driver/sub_driver/sub_driver.o -c -std=c11 -g -mcpu=cortex-m3 -mthumb -nostartfiles --specs=nosys.specs driver/sub_driver/sub_driver.c
arm-none-eabi-gcc -o main.o -c -std=c11 -g -mcpu=cortex-m3 -mthumb -nostartfiles --specs=nosys.specs main.c
arm-none-eabi-ld -o main.elf -T cm4.ld boot.o main.o driver/qemu_print.o driver/sub_driver/sub_driver.o
arm-none-eabi-objcopy -O binary -S -R .note -R .comment main.elf main.bin
arm-none-eabi-objdump -S main.elf > main.dis
scons: done building targets.