Re: (reposting) how to get DMA'able memory within 4GB on 64-bit m

From: Jeff Garzik (
Date: Sat Jul 07 2001 - 07:17:53 EST

Alan Cox wrote:
> > > that the expected lifespan for 32 bit systems is now less than 3 years, so
> > > elaborate planning that delays implementation buys us nothing more than a
> > > smaller window of usefulness.
> > Maybe by then only 64-bit cpus will matter. Who knows.
> Reality check.
> Embedded PCI 32bit processors are going to be very common
> People are only now retiring 486's
> So add another seven or eight years to your estimate

Given a little more context, I thought we were talking specifically
about 64bit-PCI-on-32bit-machines?

Assuming that, AFAICS Ben's statement seems more correct.

And IMHO we definitely should not optimize for 64-bit-on-32-bit case.
Let CONFIG_HIGHMEM grow dma_addr_t to 64-bits, for that case only...

Jeff Garzik      | A recent study has shown that too much soup
Building 1024    | can cause malaise in laboratory mice.
MandrakeSoft     |
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