Re: [PATCH] setup.c: introduce __pa_symbol() and get ride of CPHYSADDR()

[Thiemo Seufer <ths@networkno.de>]

Franck Bui-Huu wrote:
> Thiemo Seufer wrote:
> > Franck Bui-Huu wrote:
> >>
> >> -	if (CPHYSADDR(initrd_end) > PFN_PHYS(max_low_pfn)) {
> >> +	if (__pa(initrd_end) > PFN_PHYS(max_low_pfn)) {
> > 
> > ISTR this failed on O2, where kernel+initrd are loaded into KSEG0 but the
> > PAGE_OFFSET is for XKPHYS.
> > 
> 
> I guess that you were meaning somthing like:
> 
> LOADADDR    = 0xffffffff80004000
> PAGE_OFFSET = 0xa800000000000000
> 
> is that correct ?

Yes.

> If so could you explain the choice of these values
> because I fail to understand it.

It allows to load a 64-bit kernel in KSEG0, and use short 2-instruction
symbol references there. At the same time, it allows access to more
address space for memory and I/O than would fit in KSEG0.


Thiemo