What's wrong and How to upgrade my nios-gnu-tools?

Hello,

When I build uClinux Kernel, there are some errors and warnings. I note them below:

......

......

init/main.c:82:65: warning:#warning sorry, your GCC is too old. It builds incorrect kernels.

init/main.c:In function 'start_kernel';

init/main.c:560:warning: format not a string literal, argument types not checked

make[1]: *** [init/main.o] Error 1

make[1]: Leaving directory ...

make: *** [linux/linux] Error 2

I use nios2.2, and I have download nios-gnupro-src-3.2.tar.gz. But I do not know how to install it to cygwin. And what is the wrong during building kernel? Does it due to GNU tools?

Thank you.