What is the rationale behind removing crt0.o from

问题:

I am trying to upgrade to yagarto4.7.2 (Yet Another GNU ARM toolchain, for those wondering), which is gcc and binutils, ported for Windows. However, trying to compile a simple Hello World yields:

c:/yagarto-20121222/bin/../lib/gcc/arm-none-eabi/4.7.2/../../../../arm-none-eabi
/bin/ld.exe: cannot find crt0.o: No such file or directory
collect2.exe: error: ld returned 1 exit status

Now, in this forum it is made clear that this is the startup initialziation library, that was removed after gcc4.6.x. Two solutions are proposed:

• compile with -nostartfiles
• copy the crt0.o form the 4.6.x to the 4.7.x folder

Both look quite dirty and unacceptable for production code. So does anyone know why was this library removed and what is it's equivalent now?

回答1:

crt0.o is derived from crt0.s, which is provided by the OS. In the case of bare metal setup, this file must be provided by the implementation. It contains startup and exit code, for example for zeroing the .bss.