Re: new bootmem structure

Russell King (rmk@arm.linux.org.uk)
Mon, 1 Nov 1999 23:15:29 +0000 (GMT)

Jes Sorensen writes:
> Roman> Hi, Last week I was looking into the new bootmem stuff and got
> Roman> some problems how to port that to the m68k architecture. Is
> Roman> there a special reason that bootmem.c wants physical addresses?
> Roman> Logical addresses would be easier for us, since we have the
> Roman> possibility of all kinds of memory configurations, but
> Roman> bootmem.c assumes a single memory chunk starting at zero. I
> Roman> would at least suggest to add a start offset, to minimize
> Roman> memory comsumption (even if it's only at boottime).
>
> Thats the reason why we should implement PageSkip().

And the other thing I spot here is that I believe that __pa() is NOT a
short name for virt_to_phys, but __pa() is supposed to return the offset
into physical memory, not the address OF physical memory (which virt_to_phys
does).

I've already grappled with this on the ARM since we have a similar
problem - some architectures have contiguous memory starting at either
0x00000000 or 0x10000000 (physical) or even worse memory which can be
in up to 4 banks spread out across 256MB. No changes to the generic
code were necessary.
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