> I find the / was mounted to c:\mingw\msys\1.0 by default. Is there a way I
> can change such a default mount to c:\ without forcing  to put msys-1.0.dll
>  under c:\bin?

No, that is by design.  The parent directory of the directory containing
msys-1.0.dll is the root / directory and the directory containing
msys-1.0.dll is the /bin directory.

Thanks for the help. There are many convenience if I can mount / to c:\.

For example, I can run "ls /windows", "ls /other_directory" instead of using
ls /c/windows or ls /c/other_directory.

The only way is to  do it is to put msys-1.0.dll and other binary under c:\bin.
it requires me to put all msys related directory such as etc under c:\etc

I am thinking if there is a better way to do it without creating  too many msys related  sub directories under c:\?