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Date:      Wed, 11 Jan 2012 17:40:31 -0500
From:      John Baldwin <jhb@freebsd.org>
To:        Andriy Gapon <avg@freebsd.org>
Cc:        freebsd-current@freebsd.org
Subject:   Re: bus dma: a flag/quirk for page zero
Message-ID:  <201201111740.31125.jhb@freebsd.org>
In-Reply-To: <4F0DE97F.60208@FreeBSD.org>
References:  <4F0C9D14.60705@FreeBSD.org> <4F0DC476.8050509@FreeBSD.org> <4F0DE97F.60208@FreeBSD.org>

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On Wednesday, January 11, 2012 2:56:47 pm Andriy Gapon wrote:
> on 11/01/2012 19:18 Andriy Gapon said the following:
> > Actually, I think that on x86 we don't have to do anything special for any memory
> > allocations that we do, including the bounce pages, as the page zero is excluded
> > from phys_avail and is not available for normal use.
> 
> After some additional thinking there is probably no reason to take advantage of
> this fact.  First, it would increase differences with other platforms.  Second,
> it would add a hidden dependency.  So it's better to be explicit here.

Agreed.

-- 
John Baldwin



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