Re: [PATCH v2] x86: PAT: Documentation: rewrite "MTRR effects on PAT / non-PAT systems"

On Fri, Mar 04, 2016 at 04:03:04PM -0800, Paul E. McKenney wrote:

On Fri, Mar 04, 2016 at 02:45:01PM -0800, Luis R. Rodriguez wrote:

quoted

The current documentation refers to using set_memory_wc() as a
possible hole strategy when you have overlapping ioremap() regions,
that's incorrect as set_memory_*() helpers can only be used on RAM,
not IO memory. Using set_memory_wc() will not fail, that's a problem
which must be corrected in the future. This fixes that, and updates
the documention to *strongly* discourage overlapping ioremap() memory
uses, but also documents a possible solution should there really be
no other option to remain compatible on both PAT and MTRR memory
constarained systems. While at it, this provides some same guidlines
to system designers to remain sane and compatible on both PAT and
non-PAT systems.

As per Toshi this also fixes the table for the effective memory type
when using MTRR WC on PAT UC- to WC.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>

And I was really confused during my earlier reply.  For some reason
I read the filename as memory-barriers.txt.

This one is not mine.  Too much time in standards committee meetings,
I guess.  ;-)

Heh, OK yeah I was confused why you wanted to pick it up but played along.
Boris, can this go through you as its a follow up that previously went
through you ?

  Luis