Re: [PATCH] pci_alloc_consistent in an interrupt context

[Tom Rini <trini@kernel.crashing.org>]

On Fri, Jun 14, 2002 at 12:06:40PM +1000, David Gibson wrote:
> On Thu, Jun 13, 2002 at 06:57:45PM -0700, Eugene Surovegin wrote:
> >
> > At 06:33 PM 6/13/2002, David Gibson wrote:
> > >On Thu, Jun 13, 2002 at 06:25:11PM -0700, Eugene Surovegin wrote:
> > >>
> > >> At 05:24 PM 6/13/2002, David Gibson wrote:
> > >> >That's right.  But I think the patch below is a better fix for the
> > >> >problem.  It makes consistent_alloc()/consistent_free() just do the
> > >> >right thing for both cache coherent and cache non-coherent processors,
> > >> >so we can get rid of the ifdef in pci_alloc_consistent() and
> > >> >pci_free_consistent().
> > >>
> > >> So, kmalloc will allocate non-cacheable memory?
> > >>
> > >> I seriously doubt it (actually I've just tested it:).
> > >
> > >No, but on cache coherent processors we don't need non-cacheable
> > >memory.  That's the whole point.  Likewise with __get_free_pages()
> > >which is what pci_alloc_consistent() uses on cache-coherent processors
> > >now.
> >
> > OK, I got it :)
> >
> > One problem though, kmalloc allocated memory will not be necessarily
> > properly aligned
> > as required by DMA-mappings.txt
> >
> > Some PCI drivers may break because of this.
>
> Ah, yes, indeed.  How about this:

One last thing, did you mean to keep consistent_free as kfree() still
and not free_pages() ?

--
Tom Rini (TR1265)
http://gate.crashing.org/~trini/

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