Re: HIGH MEMORY access

From: Lyle Coder (x_coder@hotmail.com)
Date: Mon Apr 10 2000 - 16:28:08 EST


Ingo,
Please accept this patch as I am able to boot on machines that place the MPS
tables above 1GB with this patch.

Best Wishes,
Lyle.

>From: Manfred Spraul <manfreds@colorfullife.com>
>To: Ingo Molnar <mingo@chiara.csoma.elte.hu>
>CC: Lyle Coder <x_coder@hotmail.com>, sct@redhat.com,
>linux-kernel@vger.rutgers.edu
>Subject: Re: HIGH MEMORY access
>Date: Fri, 03 Mar 2000 15:32:18 +0100
>
>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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