Re: 2.4.4 kernel reports wrong amount of physical memory
Brian Gerst (bgerst@didntduck.org)
Mon, 14 May 2001 21:57:20 -0400
"H. Peter Anvin" wrote:
>
> Followup to: <Pine.LNX.4.33.0105142025000.18102-100000@duckman.distro.conectiva>
> By author: Rik van Riel <riel@conectiva.com.br>
> In newsgroup: linux.dev.kernel
> >
> > On Mon, 14 May 2001, Wayne Whitney wrote:
> > > In mailing-lists.linux-kernel, you wrote:
> > >
> > > > You need to compile highmem support into the kernel if you want to
> > > > use more than 890 MB of RAM, set it to maximum 4GB for best
> > > > performance...
> > >
> > > On a similar note, what is the maximum physical memory supported
> > > by the 4GB option?
> >
> > Ummm, 4GB maybe? ;)
> >
>
> It seems obvious once you know why the limits are there. The 1 GB
> limit (actually 1024-128 MB = 896 MB) is a software limit; the 4 GB
> and 64 GB limits are hardware limits and are exact.
Even with the 4GB and 64GB options, some physical address space has to
be reserved for memory mapped I/O.
--
Brian Gerst
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