Re: Cache incoherencies

Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 27 Aug 1999 15:03:16 +0100 (BST)

> technically turns into "preferably a page from non-DMA memory, but if
> you're out of those, give me a DMA-able page".
>
> A driver wanting to do DMA will request "a DMA-ABLE page" (with either
> the 16M ISA limit, the 1M XT limit, or the 4G PCI limit!), with "if
> you're out of those, give up".

Or a 27bit Maestro addressable limit, a 28bit limit on another card and so on.

> I think that GFP may need to be redesigned one time or another.
> However, once that is done, taking along things as "uncached" pages,
> should become a breeze. Yes, the current implementation makes it a
> quick hack to vmalloc.
>
> I think that generalizing gfp is a good idea in the end.

I think the gfp flags are simply inadequate. But lets hit that wall when
we need to ?

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