This is changing. The new patches will be reclaim-enabled, so those pages
will be mapped, and the max_pfn-class variables will reflect their presence.
Nathan
> -----Original Message-----
> From: Manfred Spraul [mailto:manfreds@colorfullife.com]
> Sent: Friday, March 03, 2000 8:32 AM
> To: Ingo Molnar
> Cc: Lyle Coder; sct@redhat.com; linux-kernel@vger.rutgers.edu
> Subject: Re: HIGH MEMORY access
>
>
> Ingo Molnar wrote:
> >
> > On Fri, 3 Mar 2000, Manfred Spraul wrote:
> >
> > > Now I'm confused: I thought that ioremap() should be used
> for reserved
> > > memory, and kmap() for normal memory (e820: ram) with
> > > page->virtual==NULL.
> >
> > well you can use kmap() for anything, not just high memory.
>
> kmap() assumes that a "struct page" exists.
>
> It's not guaranteed that a "struct page" exists for reserved memory:
> this could happen if you boot with "mem=32M", or if the ACPI
> tables are
> the last element in the e820 map:
>
> * max_pfn is set to the end if the last usable block.
> * then the ACPI tables follow --> they are behind max_pfn -->
> behind the
> end of mem_map.
>
> Not everyone has 8 GB memory :-(
>
> --
> Manfred
>
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