host为ubuntu16.04
下载相关工具
$ sudo apt-get install automake bison chrpath flex g++ git gperf gawk libexpat1-dev libncurses5-dev libsdl1.2-dev libtool python2.7-dev texinfo
安装过程
$ git clone https://github.com/crosstool-ng/crosstool-ng.git $ cd crosstool-ng $ git checkout crosstool-ng-1.22.0 $ ./bootstrap $ ./configure --enable-local $ make $ make install
--enable-local选项代表安装在当前目录下。
过程中出现configure: error: could not find GNU libtool >= 1.5.26
解决方法
$ sudo apt install libtool-bin
列出可用的示例
$ ./ct-ng list-samples
可用加上show前缀来显示具体信息
$ ./ct-ng show-arm-cortexa9_neon-linux-gnueabihf
[L.X] arm-cortexa9_neon-linux-gnueabihf
OS : linux-4.3
Companion libs : gmp-6.0.0a mpfr-3.1.3 mpc-1.0.3 expat-2.1.0 ncurses-6.0
binutils : binutils-2.22
C compilers : gcc | 5.2.0
Languages : C,C++
C library : glibc-2.22 (threads: nptl)
Tools : gdb-7.10
和编译kernel一样，执行下列将sample配置写入.config
$ ./ct-ng arm-cortexa9_neon-linux-gnueabihf
执行下列可进行配置
$ ./ct-ng menuconfig
执行下列命令开始构建
./ct-ng build
大约一个小时可以编译完成（e3-1230v2),编译完成后会在家目录生产x-tools目录，
~/x-tools/arm-cortexa9_neon-linux-gnueabihf/bin存放二进制编译工具。
PATH=~/x-tools/arm-cortexa9_neon-linux-gnueabihf/bin/:${PATH}加入环境变量
编写测试程序
$ vim test.c #include <stdio.h> int main(void) { printf("hello world "); return 0; } $ arm-cortexa9_neon-linux-gnueabihf-gcc test.c $ file a.out a.out: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, for GNU/Linux 2.6.32, not stripped
成功编译
查看版本信息
$ arm-cortexa9_neon-linux-gnueabihf-gcc --version arm-cortexa9_neon-linux-gnueabihf-gcc (crosstool-NG crosstool-ng-1.22.0) 5.2.0 Copyright (C) 2015 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
查看配置信息
$ arm-cortexa9_neon-linux-gnueabihf-gcc -v Using built-in specs. COLLECT_GCC=arm-cortexa9_neon-linux-gnueabihf-gcc COLLECT_LTO_WRAPPER=/home/rzx/x-tools/arm-cortexa9_neon-linux-gnueabihf/libexec/gcc/arm-cortexa9_neon-linux-gnueabihf/5.2.0/lto-wrapper Target: arm-cortexa9_neon-linux-gnueabihf Configured with: /home/rzx/work/crosstool-ng/.build/src/gcc-5.2.0/configure --build=x86_64-build_pc-linux-gnu --host=x86_64-build_pc-linux-gnu --target=arm-cortexa9_neon-linux-gnueabihf --prefix=/home/rzx/x-tools/arm-cortexa9_neon-linux-gnueabihf --with-sysroot=/home/rzx/x-tools/arm-cortexa9_neon-linux-gnueabihf/arm-cortexa9_neon-linux-gnueabihf/sysroot --enable-languages=c,c++ --with-cpu=cortex-a9 --with-fpu=neon --with-float=hard --with-pkgversion='crosstool-NG crosstool-ng-1.22.0' --enable-__cxa_atexit --disable-libmudflap --disable-libgomp --disable-libssp --disable-libquadmath --disable-libquadmath-support --disable-libsanitizer --with-gmp=/home/rzx/work/crosstool-ng/.build/arm-cortexa9_neon-linux-gnueabihf/buildtools --with-mpfr=/home/rzx/work/crosstool-ng/.build/arm-cortexa9_neon-linux-gnueabihf/buildtools --with-mpc=/home/rzx/work/crosstool-ng/.build/arm-cortexa9_neon-linux-gnueabihf/buildtools --with-isl=/home/rzx/work/crosstool-ng/.build/arm-cortexa9_neon-linux-gnueabihf/buildtools --with-cloog=/home/rzx/work/crosstool-ng/.build/arm-cortexa9_neon-linux-gnueabihf/buildtools --with-libelf=/home/rzx/work/crosstool-ng/.build/arm-cortexa9_neon-linux-gnueabihf/buildtools --enable-lto --with-host-libstdcxx='-static-libgcc -Wl,-Bstatic,-lstdc++,-Bdynamic -lm' --enable-threads=posix --enable-plugin --enable-gold --disable-multilib --with-local-prefix=/home/rzx/x-tools/arm-cortexa9_neon-linux-gnueabihf/arm-cortexa9_neon-linux-gnueabihf/sysroot --enable-long-long Thread model: posix gcc version 5.2.0 (crosstool-NG crosstool-ng-1.22.0)
几个重点参数
--with-sysroot=/home/chris/x-tools/arm-cortex_a8-linuxgnueabihf/arm-cortex_a8-linux-gnueabihf/sysroot: This is the default sysroot directory; see the following section for an explanation
--enable-languages=c,c++: Using this, we have both C and C++ languages enabled
--with-cpu=cortex-a8: The code is generated for an ARM Cortex A8 core
--with-float=hard: Generates opcodes for the floating point unit and uses the VFP registers for parameters
--enable-threads=posix: This enables the POSIX threads
这些默认的配置信息可以通过使用时在命令行进行重写，例如
$ arm-cortex_a8-linux-gnueabihf-gcc -mcpu=cortex-a5 helloworld.c -o helloworld
查看相关帮助
$ arm-cortexa9_neon-linux-gnueabihf-gcc --target-help
所以说，构建编译链有两种思想：
1.buildroot在开始时就进行详细正确的配置。
2.yocto构建比较通用的形式，针对不同target进行重写。