[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20100115220153.GE10591@ovro.caltech.edu>
Date: Fri, 15 Jan 2010 14:01:53 -0800
From: "Ira W. Snyder" <iws@...o.caltech.edu>
To: Stefani Seibold <stefani@...bold.net>
Cc: linux-kernel <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Andi Kleen <andi@...stfloor.org>,
Greg Kroah-Hartman <gregkh@...e.de>,
Alan Cox <alan@...rguk.ukuu.org.uk>,
Theodore Tso <tytso@....edu>
Subject: Re: [PATCH] enhanced reimplemented of the kfifo API
On Fri, Jan 15, 2010 at 10:30:01PM +0100, Stefani Seibold wrote:
>
> > I'm glad to see this example, it really illustrates how to use the new
> > DMA functionality of the kfifo API.
> >
> > Is there any reason why a very large scatterlist could not be used? I
> > have a driver that uses a large scatterlist (~4000 entries, allocated as
> > a struct sg_table). I implemented my own copy_from_user() functionality
> > into this scatterlist, but I'd love to use the kfifo DMA API instead.
> > After filling the scatterlist, I use the usual DMA API's to transfer it
> > to my device.
> >
>
> No, but the API will only return max. two entries.
>
Ah, I see. __kfifo_alloc() uses kmalloc() internally. The kfifo API will
not work for my purposes then, since I want to allocate a 16MB chunk of
memory, and I'm very uncomfortable doing that with kmalloc(). I'll stick
with my custom scatterlist code, which uses alloc_page() to fill in the
scatterlist with order-0 allocations.
Another nitpick in the code: I've noticed that you use sgl++ in the
setup_sgl() function. That should become "sgl = sg_next(sgl);" so that
this code can work with an struct sg_table as well.
Thanks,
Ira
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists