/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/crt1.o: In function `_start':

`_start` is a special function in the C runtime library that is called at the beginning of a program's execution. The error message you provided indicates that there was an issue with the `_start` function in the `crt1.o` object file, which is a system file that is linked into your program automatically by the linker.

This error message suggests that there may be a problem with your compiler or the system libraries on your machine. One possible cause of this error is a missing or corrupt `libc` library, which provides the standard C library functions used by many programs. You may want to try reinstalling your system's C runtime libraries to see if that resolves the issue.

It's also possible that there is a problem with your code itself, such as a missing `main` function. Make sure that your code is properly structured and free of syntax errors.

If you're still having trouble, you may want to consult with a more experienced programmer or seek help from online forums or support communities.