Re: [PATCHSET] block: fix PIO cache coherency bug, take 2

[Russell King]

On Mon, Jun 05, 2006 at 10:47:40AM -0500, James Bottomley wrote:
> On Mon, 2006-06-05 at 16:34 +0100, Russell King wrote:
> > What has zero copy (your reply) got to do with faulting pages into
> > userspace (my message).  I'm sorry, I don't understand why you've
> > brought this up.
> 
> The zero copy case is the case where we end up with user and kernel
> mappings simultaneously on the page.  The nopage (or fault) case is
> where we end up with them sequentially.  Both cases actually require the
> same cache treatment, but it's easiest to understand in the zero copy
> case.

When does the zero copy case occur?

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core
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