Re: [PATCH] kiobuf/rawio fixes for 2.4.0-test10-pre6

From: Christoph Hellwig (hch@caldera.de)
Date: Mon Oct 30 2000 - 13:17:12 EST


On Mon, Oct 30, 2000 at 12:19:21PM -0500, Jeff Garzik wrote:
> Christoph Hellwig wrote:
> > +Locking down user memory and doing mass storage device IO with it is not
> > +the only purpose of kiobufs. Another use for kiobufs is allowing
> > +user-space mmaping dma memory, e.g in sound drivers. To do so you
> > +need to lock-down kernel virtual memory and refernece it using kiobufs.
> > +The code that does exactly this is not yet in the kernel - get Stephen
> > +Tweedie's kiobuf patchset if you want to use this.
>
> Take a look at drivers/sound/via82cxxx_audio.c. How can that mmap be
> improved by using kiobufs?

I think so - but you need Stephen's kvmap patch, that is in the same
patchset the forward-ported fixes are
(at ftp://ftp.linux.org.uk/pub/linux/sct/fs/raw-io/)

An very nice example is included.

        Christoph

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