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Subject: Re: [PATCH v2 6/6] x86, pat: Update documentation for WT changes
From: Toshi Kani <toshi.kani@hp.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
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        Yigal Korman <yigal@plexistor.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Wed, 10 Sep 2014 14:12:13 -0600
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On Wed, 2014-09-10 at 11:30 -0700, Andy Lutomirski wrote:
> On Wed, Sep 10, 2014 at 9:51 AM, Toshi Kani <toshi.kani@hp.com> wrote:
> > +Drivers may map the entire NV-DIMM range with ioremap_cache and then change
> > +a specific range to wt with set_memory_wt.
> 
> That's mighty specific :)

How about below?

Drivers may use set_memory_wt to set WT type for cached reserve ranges.

> It's also not all that informative.  Are you supposed to set the
> memory back before iounmapping?  

Setting back to WB before iounmap is not required, but set_memory_wb is
used when it wants to put it back to WB before unmapping.

> Can you do this with set_memory_wc on
> an uncached mapping?

The table lists interfaces and their intended usage.  Using
set_memory_wc on an uncached mapping probably works, but is not an
intended use.

Thanks,
-Toshi