Re: virt_to_bus and >1G of memory (was MAX_DMA_ADDRESS ...)
Kurt Garloff (garloff@kg1.ping.de)
Thu, 12 Nov 1998 15:59:38 +0100
On Wed, Nov 11, 1998 at 07:58:36PM +0100, Jan Kasprzak wrote:
>
> In my previous mail I wrote:
> : And another question related to the virt_to_bus on x86:
> : This function is defined as (x) & ~PAGE_OFFSET. It works for the current
> : value of the PAGE_OFFSET, but IMHO it does not work when I change the
> : PAGE_OFFSET to 0x70000000, as suggested in <asm-i386/page.h> for >1GB RAM
> : machines. Shouldn't the virt_to_bus be defined as (x)-PAGE_OFFSET ?
> : The physical memory is mapped 1:1 from the PAGE_OFFSET virtual address, IIRC.
Reading this, I wonder, why my kernel with PAGE_OFFSET 0x70000000 does work.
Somebody able to explain this?
--
Kurt Garloff <K.Garloff@ping.de> (Dortmund, FRG)
PGP key on http://student.physik.uni-dortmund.de/homepages/garloff
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