Also, the PIII CAN'T natively support more than 4GB of ram. If a
particular PIII motherboard supports this, then it's using some kind of
wierd chipset that allows this to happen. 4GB is the limit with a 32 bit
chip I believe; and the PIII is a 32-bit chip.
Ken
On Thu, 2 Aug 2001, Rik van Riel wrote:
> On Wed, 1 Aug 2001, Terry Lambert wrote:
> > > craig wrote:
> > >
> > >
> > > I know PIII can support 64G physical memory. In FreeBSD how can I visit such
> > > range memory(4G-64G) ?
> >
> > The short answer is "you can't".
> >
> > The longer answer is that you end up having to window it using
> > segmentation;
>
> Only if you want to use it all within one process.
>
> You can have multiple 2 GB (that's the maximum
> process size in FreeBSD, right?) programs at the
> same time, happily using all physical memory.
>
> Only the FreeBSD memory management subsystem doesn't
> support it (yet?).
>
> > This basically means that the memory is useless as a DMA target
> > or source for disk controllers or gigabit ethernet cards, and is
> > pretty useless for swap, ...
>
> > So for limited uses in data intensive applications, it might be
> > usable,
>
> And for those data intensive applications, it is very
> useful indeed...
>
> > But to directly answer your question: by rewriting much of the
> > low core virtual memory and page mapping handling code to know
> > about segmentation.
>
> Not just that. There is a more insidious problem with
> the FreeBSD VM code and support of huge machines.
>
> The part of handling the PAE extended page table format
> and mapping high memory pages in and out of KVA (kernel
> virtual address) memory to copy stuff is easy.
>
> Problem is that you'll have to fit all of FreeBSD's VM
> data structures in the 2GB of KVA. This just isn't going
> to fit with the size the data structures have today ...
>
> So in order to support huge memory machines "right",
> you'd have to put a number of FreeBSD's VM data structures
> on a rather strict diet.
>
> regards,
>
> Rik
> --
> Executive summary of a recent Microsoft press release:
> "we are concerned about the GNU General Public License (GPL)"
>
>
> http://www.surriel.com/
> http://www.conectiva.com/ http://distro.conectiva.com/
>
>
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