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Date: Sun, 16 Aug 2015 12:03:58 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: Roger Pau Monn?? <royger@FreeBSD.org>
Cc: Jason Harmening <jason.harmening@gmail.com>,
 "Jason A. Harmening" <jah@FreeBSD.org>, src-committers@freebsd.org,
 svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject: Re: svn commit: r286787 - head/sys/x86/x86
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On Sun, Aug 16, 2015 at 10:16:53AM +0200, Roger Pau Monn?? wrote:
> pmap_map_io_transient contains some of this logic, but it uses
> vmem_alloc (with M_WAITOK) instead of a pcpu pageframe, which defeats
> part of the purpose of this change and cannot be used as-is.

This logic can be repeated, but it is probably too much for the purpose.
It would be enough to have single frame (we cannot reuse CMAP1),
protected by a spin mutex.  I do not see much sense in providing
optimized per-cpu frames for this case.