romcc fixes for AMD64

[Eric W. Biederman]

Stefan Reinauer <stepan at suse.de> writes:

> Hi,
> 
> with the attached fix romcc is able to compile all of auto.c
> for the freebios2 amd64 targets. To keep all changes clean 
> and visible, they're encapsulated in ifdefs.
> 
> Note: This fix alone does not make LinuxBIOS compile on AMD64
> completely yet. GCC and ld need the -m32 in some places at least
> to compile everything. 

The -m32 can easily be added in the compiler over rides so that is simple
enough.

> Is there any need in going 64bit for the LinuxBIOS C payload
> on Opteron? Since the kernel does long mode switching itself
> this should not be the case, but maybe there are different 
> opinions.

There is not any need yet.  But there are certainly advantages.
So far keeping it 32bit has made things simpler.  Ideally I'd
like to be able to do either.

> Next fail I saw after romcc passed auto.c was the following:
> /home/stepan/freebios2/src/superio/NSC/pc87360/superio.c:61: warning:
> `pnp_read_enable' defined but not used

> 
> /tmp/ccLriZXb.s: Assembler messages:
> /tmp/ccLriZXb.s:243: Error: Incorrect register `%rdx' used with `l' suffix
> /tmp/ccLriZXb.s:245: Error: Incorrect register `%rdx' used with `l' suffix
> make: *** [superio.o] Error 1

Hmm.  This looks like an inline assembler problem.

Eric