Re: Address spaces on a i386 - Getting Confused

Brian Gerst (bgerst@quark.vpplus.com)
Thu, 01 Apr 1999 16:00:57 -0500

Stephen C. Tweedie wrote:
>
> Hi,
>
> On Thu, 1 Apr 1999 09:11:55 -0500 , Eric Lowe <ELowe@SYSTRAN.com> said:
>
> > How about a dmamalloc() function?
>
> In the kernel, use GFP_DMA for dma-capable, physically contiguous memory
> (only for ISA dma right now, as that is limited to 16MB; PCI can always
> dma all of physical memory right now, as we don't support more than 4G
> physical ram on Intel). In user space, use valloc() to get page-aligned
> memory.

That's a really bad assumption. There WILL eventually be a time when
this is no longer true, so something should be done now to head this
off. Adding a GFP_DMAPCI or whatever, even if it only currently maps to
another value, will make life a whole lot easier when we start seeing
systems with >4G memory with 32-bit PCI cards. And what about other
arches besides Intel?

-- 


						Brian Gerst


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