问题描述： 在gcc4.9，gdb7.0环境下，启动gdb时出现了如下错误：Dwarf Error: wrong version in compilation unit header (is 4, should be 2) [in module /dawnfs/users/ 出现此错误的原因主要是gcc4.9生成的调试信息是dawnfs4，而gdb7.0支持的是 dawnfs2
问题描述：在gcc4.9，gdb7.0环境下，启动gdb时出现了如下错误：Dwarf Error: wrong version in compilation unit header (is 4, should be 2) [in module /dawnfs/users/ 出现此错误的原因主要是gcc4.9生成的调试信息是dawnfs4，而gdb7.0支持的是dawnfs2
解决方案：这个问题其实是编译环境的问题，可以更改gcc和gdb的版本，这需要去寻找合适的版本。当然也可以给gcc增加编译参数，使其生成dawnfs2调试信息，主要参数为-gdwarf-2 -gstrict-dwarf，做法如下：
在.bashrc中加入alias gcc='gcc -gdwarf-2 -gstrict-dwarf'，重启终端使其生效
这样gdb可以使用，也不会出现上面的错误。
参考gcc文档：https://gcc.gnu.org/gcc-4.5/changes.html
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