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Re: [patch] adjust libgloss addresses for 64-bit
Maciej W. Rozycki wrote:
> On Fri, 15 Apr 2005, Eric Christopher wrote:
>
> > > > > leaving us with a zero-extended value in a register which is
> > > > > unpredictable as far as the standard (and at least one chip out there)
> > >
> > > Hmm, 0x80000000 should be a valid XKUSEG address...
> > >
> >
> > Nothing wrong with the address, but it's loaded as:
> >
> > ori $2,0x8000
> > dsll $2,$2,0x10
> >
> > so it's zero extended and not sign extended as it should be.
>
> Of course it is zero-extended. Otherwise it would be a different one;
> actually in the CKSEG0 space rather than XKUSEG. If you want the former,
> what's wrong with 0xffffffff80000000? -- please keep in mind we are
> talking about 64-bit addressing.
But people used to use "la $2, 0x80000000" in order to get a sign-extended
address. Loading two different addresses with the same code is at least
surprising. I see la in 64bit mode as backward compatibility legacy, and
this suggests not to change its behaviour.
Thiemo