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

From: Jens Axboe
Date: Tue Sep 11 2007 - 07:17:06 EST


On Tue, Sep 11 2007, David Howells wrote:
> Jens Axboe <jens.axboe@xxxxxxxxxx> 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

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