fc1_x86_64 preview on tyan thunder k8w (S2885ANRF REV .03)
Thomas Dodd
ted at cypress.com
Thu Dec 11 22:56:35 UTC 2003
Alan Cox wrote:
> On Thu, Dec 11, 2003 at 04:11:26PM -0600, Thomas Dodd wrote:
>
>>It was sort of explained before by Mark. What was ment is you _cannot_
>>use the last .5G because it's mapped to PCI.
>
>
> Thats the physical memory map. Because PCI is 32bit for some cards you
> end up with a PCI hole (remember the ISA hole.. now we have two 8))
That makes sense. Thanks Alan.
> So its
>
> 0-639K RAM
> 640K-1Mb ISA + ROM window
Is the and ISA bus on any x86-64 board?
Is it possible?
I don't think you can even find a SocketA board with ISA slots.
I have a ISA card I cannot replace right now that's keept me on a SlotA
board and a lowly 800MHz Thunderbird Athlon.
>>There may be some trick to move that though. I remember this was a
>>problem for 32bit too. PCI+kernel took the last 1GB on a 4GB box, so
>>processes only got 3GB. There were sopme hack to get 3.5GB on those, so
>>it might be posible to get more on 64bit systems. Maybe only loose 0.25GB?
>
>
> Thats different. You end up needing some mappings for kernel and user
> space to be efficient when dealing with user mappings. Whether you can
> get your .5Gb back depends if the chipset can remap it higher up in memory
> so that the 3.5-4Gb RAM masked by PCI is remapped at the top of memory.
Know which ones, if any, currently can? AMD, Nvidia, or VIA?
Why would they release a chip that couldn't?
-Thomas
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