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Date:      Wed, 31 Dec 2014 13:40:03 -0500
From:      John Baldwin <jhb@freebsd.org>
To:        Rui Paulo <rpaulo@me.com>
Cc:        svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Andrew Turner <andrew@fubar.geek.nz>, Ian Lepore <ian@freebsd.org>
Subject:   Re: svn commit: r276187 - head/sys/arm/arm
Message-ID:  <201412311340.03637.jhb@freebsd.org>
In-Reply-To: <9F69A6CD-D352-4A91-97F6-B3E1FF638211@me.com>
References:  <201412241712.sBOHCqvW039381@svn.freebsd.org> <1419471084.1018.160.camel@freebsd.org> <9F69A6CD-D352-4A91-97F6-B3E1FF638211@me.com>

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On Wednesday, December 24, 2014 9:05:47 pm Rui Paulo wrote:
> On Dec 24, 2014, at 17:31, Ian Lepore <ian@FreeBSD.org> wrote:
> > In every architecture and every place it's used, or just arm just here?
> 
> You're right, it can be found at least in MIPS and amd64.
> 
> > This appears to be an idiom, or at least something that has been pasted
> > in identical form in every arch so far.
> 
> The idiom is a bit different in amd64: the variable in the for-loop isn't 
immediately reused, but it's a global variable anyway...  That's what I 
thought deserves a comment.
> 
> Regarding the pmap_kenter_temporary(), the first problem is the function 
name: it might be a temporary mapping, but the real use is for crash dumps (I 
wonder why ACPI abuses this mapping).  The other problem is the fact that a 
pmap function is so tied to crash dumps.  However, that's a bigger problem.

ACPI abuses it because it is available (and we can't possibly generate a crash
dump early when ACPI uses it).  ACPI is only use it to map ACPI tables before
the VM system is initalized enough to map the tables using normal KVA.

-- 
John Baldwin



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