gaisler and classic rtems release differences

[Luca Cinquepalmi]

Hi all,
i'm trying do compile rtems C code in order to load it on a leon2 cpu board.
If I use Gaisler rtems release I have no problem to compile it, and it 
works without
any problem.
But if I try to compile classic rtems, as reported at Quick Start or 
Getting started with rtems
document, the gcc ompilers aren't able to compile C source code.
Are there any difference between Classic an Gaisler rtems releases?
Thanks a lot

     Luca