解決製作交叉編譯工具鏈時報錯“/libgcc.mvars: No such file or directory make”
當自己手動製作交叉編譯工具鏈時，需要編譯binutils，gcc等，其中編譯過程絕對是很糾結的，一次通過的可能性不大，本文只針對一種型別的錯誤進行說明。
錯誤示例如下：
$ make
test -f config.h || (rm -f stamp-h1
&& make stamp-h1) make[2]: Leaving directory /home/zql/build/arm64-toolchain/gcc/aarch64-branch/host-x86_64-unknown-linux-gnu/libcpp'
make[2]: Entering directory/home/zql/build/arm64-toolchain/gcc/aarch64-branch/host-x86_64-unknown-linux-gnu/libdecnumber'
make[2]: Nothing to be done for all'. make[2]: Leaving directory/home/zql/build/arm64-toolchain/gcc/aarch64-branch/host-x86_64-unknown-linux-gnu/libdecnumber'
make[2]: Entering directory /home/zql/build/arm64-toolchain/gcc/aarch64-branch/host-x86_64-unknown-linux-gnu/gcc'
make[2]: Leaving directory/home/zql/build/arm64-toolchain/gcc/aarch64-branch/host-x86_64-unknown-linux-gnu/gcc'
Checking multilib configuration for libgcc... make[2]: Entering directory /home/zql/build/arm64-toolchain/gcc/aarch64-branch/aarch64-none-linux/libgcc'
Makefile:161: ../.././gcc/libgcc.mvars: No such file or directory make[2]: *** No rule to make target../.././gcc/libgcc.mvars'.
Stop. make[2]: Leaving directory /home/zql/build/arm64-toolchain/gcc/aarch64-branch/aarch64-none-linux/libgcc'
make[1]: *** [all-target-libgcc] Error 2 make[1]: Leaving directory
編譯gcc時，需要注意一個原則：不要再gcc的原始碼中直接執行./configure、make、make install等命令，需要在原始碼目錄下另外新建一個目錄，在新建的目錄中執行以上命令。
If you encounter seemingly strange errors when trying to build the compiler in a directory other than the source directory, it could be because you have previously configured the compiler in the source directory. Make sure you have done all the necessary preparations.
不要小看這個提示，好多錯誤都出自這裡。好，問題有了，解決辦法呢？很簡單：假如gcc原始碼在/source目錄下，
# cd /source
# mkdir build
# cd build
# ../configure....
# make...
以上指令的意思就是，在gcc的原始碼目錄下新建一個目錄，然後進入這個目錄中執行configure，因為新建了目錄，所以configure程式在上一個目錄中，需要用".../configre"命令執行配置命令。
還有個需要注意的，如果編譯一次報錯了，沒通過，需要執行make distclean清除以前的殘留資訊，或者乾脆重新解壓一份新原始碼再次編譯。
Now,問題解決！