Re: [PATCH] pci_alloc_consistent in an interrupt context

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:

quoted

At 06:33 PM 6/13/2002, David Gibson wrote:

quoted

On Thu, Jun 13, 2002 at 06:25:11PM -0700, Eugene Surovegin wrote:

quoted

At 05:24 PM 6/13/2002, David Gibson wrote:

quoted

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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