From: Jens Axboe <jens.axboe@oracle.com>
To: David Howells <dhowells@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Ungerer <gerg@snapgear.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm] splice: Disable vmsplice on nommu.
Date: Tue, 11 Sep 2007 13:25:27 +0200 [thread overview]
Message-ID: <20070911112526.GK15405@kernel.dk> (raw)
In-Reply-To: <9949.1189505419@redhat.com>
On Tue, Sep 11 2007, David Howells wrote:
> Jens Axboe <jens.axboe@oracle.com> wrote:
>
> > It's a bit of a sledge hammer... Since get_user_pages() appears to work
> > on nummu, we can just disable the vmsplice-to-userspace bits and leave
> > the (working) vmsplice-from-userspace in place.
>
> That sounds about right. I don't think you can do the latter without
> an MMU, but I may be wrong about what it does.
You mean the former? The latter is vmsplice() filling a pipe with user
pages, using get_user_pages() to set them up. And that looks like it
should work on nommu.
The former is vmsplice() using mmap like functionality to map pages into
a user vma.
Just making sure we agree :-)
--
Jens Axboe
next prev parent reply other threads:[~2007-09-11 11:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-11 8:23 [PATCH -mm] splice: Disable vmsplice on nommu Paul Mundt
2007-09-11 9:35 ` Jens Axboe
2007-09-11 10:10 ` David Howells
2007-09-11 11:25 ` Jens Axboe [this message]
2007-09-11 16:57 ` David Howells
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