optimization issue about -O2 and -Os

[Ebony Zhu]

Hi, Everybody,

I'm new to this mailing list. I encountered an odd issue about gcc
optimization. I'm using a cross-built gcc 3.3.2 for Powerpc. When I
build some applications such as U-Boot, Busybox..., with the -Os
optimization, the apps can be built but cannot run (just halted, there
were even no error messages). If I use -O2 switch then everything is OK.

According to manpage of GCC, -Os is based on -O2 switch and does some
work to reduce the code size. What GCC did on earth with the -Os switch?

Anybody has some idea about this odd issue? Many thanks!

B.R.
EBony