Why is libphobos not a shared library?

["拖狗散步"]

On Monday, 18 June 2012 at 00:59:02 UTC, 拖狗散步 wrote:
> dmd -shared testlib.d
>
> error:
>
> relocation R_X86_64_32 against '.data' can not be used when 
> making a shared object; recompile with -fPIC
>
> could not read symbols:bad value
>
> so gdc error。。。
>
> my system is ubuntu 64b

Brothers help me!