[OpenBIOS] cross-pcc compilation issue with GCC 4.5.0

[Paul Brook]

> > So until then the GCC folks' answer is: If your code uses compile time
> > options that change the ABI of your compiler, you need to compile a
> > compiler (well, libgcc) with those options, too.
> 
> No, that is not the party line.

Huh?  If you use ABI changing options then you need libraries that match. This 
includes libgcc.  In rare cases it may be possible to get limited 
iteroperation, but this is the exception rather than the rule.
 
> > So the simplest way is
> > just not assuming any ABI details if possible and not using CFLAGS that
> > change the default ABI.
> 
> Sure, but then you have to build a compiler that defaults to the ABI you
> want.  Note that this anyway doesn't solve the regparm model, and also
> not the Sparc -mcmodel problem AFAICS.
> 
> The "simplest way" to fix it would be first to figure out exactly what
> is actually wrong, and go from there.

You can't assume that an object/library (in particular libgcc) compiled for 
one target environment will work on a different target, even if they nominally 
use the same ABI. For example in a linux userspace environment the correct way 
to indicate division by zero may be a raise/kill syscall. Obviously this is 
completely bogus in a bare metal environment.

If you want to use the wrong toolchain (e.g. a linux targeted compiler for 
bare metal applications such as bootloaders or kernels) then you should expect 
to have to jump though hoops. The hacks required vary by both architecture and 
compiler version, and range from making sure you never write particular code 
sequences to providing your own implementation of all the libgcc routines.  
This is an internal compiler ABI, so the requirements may change without 
warning.

Paul