Messages in this thread | | | Subject | Re: i686 SMP systems with more then 12 GB ram with 2.4.x kernel ? | Date | Tue, 1 Jan 2002 18:46:40 +0000 (GMT) | From | Alan Cox <> |
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> 1. Shouldn't there be *four* zones: (DMA, low, high and PAE)?
Probably not. PAE isnt special. With PAE you pay the page table penalties for all RAM.
> 2. Isn't the boundary at 2^30 really irrelevant and the three "correct" > zones are (0 - 2^24-1), (2^24 - 2^32-1) and (2^32 - 2^36-1)?
Nope. The limit for directly mapped memory is 2^30.
> 3. On a system without ISA DMA devices, can DMA and low be merged into a > single zone?
Rarely. PCI vendors are not exactly angels when it comes to implementing all 32bits of a DMA transfer
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