Re: [PATCH v2 08/25] powerpc/8xx: Map IMMR area with 512k page at a fixed address

On Fri, 2015-09-25 at 14:46 +0000, David Laight wrote:

From: Scott Wood

quoted

Sent: 24 September 2015 21:14

quoted

Isn't this a more general problem?

If there are multiple remap requests for the same physical page
shouldn't the kernel be just increasing a reference count somewhere
and returning address in the same virtual page?
This should probably happen regardless of the address.
I presume it must be done for cacheable mappings.

Why would you assume that?

Because 'really horrid (tm)' things happen on some cache
architectures if you map the same physical address to
multiple virtual addresses.

PPC is not such an architecture.

-Scott