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Date: Thu, 03 Jul 2014 08:41:33 -0700
From: Dave Hansen <dave@sr71.net>
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To: Andrea Arcangeli <aarcange@redhat.com>, qemu-devel@nongnu.org,
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Subject: Re: [PATCH 00/10] RFC: userfault
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On 07/02/2014 09:50 AM, Andrea Arcangeli wrote:
> The MADV_USERFAULT feature should be generic enough that it can
> provide the userfaults to the Android volatile range feature too, on
> access of reclaimed volatile pages.

Maybe.

I certainly can't keep track of all the versions of the variations of
the volatile ranges patches.  But, I don't think it's a given that this
can be reused.  First of all, volatile ranges is trying to replace
ashmem and is going to require _some_ form of sharing.  This mechanism,
being tightly coupled to anonymous memory at the moment, is not a close
fit for that.

It's also important to call out that this is a VMA-based mechanism.  I
certainly can't predict what we'll merge for volatile ranges, but not
all of them are VMA-based.  We'd also need a mechanism on top of this to
differentiate plain not-present pages from not-present-because-purged pages.

That said, I _think_ this might fit well in to what the Mozilla guys
wanted out of volatile ranges.  I'm not confident about it, though.