[PATCH] Use Normal uncached memory rather than Strongly Ordered on ARMv6+

[Catalin Marinas]

On Fri, 2009-10-23 at 22:33 +0100, Russell King - ARM Linux wrote:
> On Fri, Oct 23, 2009 at 06:12:27PM +0100, Russell King - ARM Linux wrote:
> > As far as I'm concerned, we've spent far too long discussing this issue -
> > there's nothing really to discuss.  We need dma_alloc_coherent() to use
> > its own page protection modifier, which causes it to behave the same as
> > dma_alloc_writecombine() on ARMv7, and with the existing behaviour (for
> > the time being) on ARMv6 and below.  We should leave pgprot_noncached()
> > well alone until we know that its other places need to be changed.
> 
> And here is the patch which does this.  Note that it also ensures that
> NX is set for these pages on both ARMv6 and later.

With Abhijeet's comment for mb(), I'm ok with the patch.

There are a few other explicit uses for pgprot_noncached() in the kernel
but I don't think they affect us yet. Some of them could probably be
changed to writecombine.

For /dev/mem, I still think we should do what IA-64 or PPC do - using
cached or writecombine if it is known to be RAM (yes, I know what you
said in the previous e-mails, it's not simple but I'll try to post
another patch for that).

-- 
Catalin