linux-kernel - Re: [PATCH -mm] splice: Disable vmsplice on nommu.

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Date:	Tue, 11 Sep 2007 17:57:17 +0100
From:	David Howells <dhowells@...hat.com>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	dhowells@...hat.com, Paul Mundt <lethal@...ux-sh.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg Ungerer <gerg@...pgear.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -mm] splice: Disable vmsplice on nommu.

Jens Axboe <jens.axboe@...cle.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.

Sorry, yes.  The former.

David
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