Re: alpha iommu fixes

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Mon May 21 2001 - 03:03:30 EST


> Alan Cox writes:
> > And how do you propose to implemnt cache coherent pci allocations
> > on machines which lack the ability to have pages coherent between
> > I/O and memory space ?
>
> Pages, being in memory space, are never in I/O space.

Ok my fault. Let me try that again with clearer Linux terminology.

Pages allocated in main memory and mapped for access by PCI devices. On some
HP systems there is now way for such a page to stay coherent. It is quite
possible to sync the view but there is no sane way to allow any
pci_alloc_consistent to succeed

Alan

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