From: Andrea Arcangeli <andrea@suse.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Daniel Jacobowitz <dan@debian.org>,
Andrew Morton <akpm@zip.com.au>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH?] Crash in 2.4.17/ptrace
Date: Tue, 29 Jan 2002 00:57:36 +0100 [thread overview]
Message-ID: <20020129005736.I1309@athlon.random> (raw)
In-Reply-To: <3C55C2AB.AE73A75D@zip.com.au> <20020128221529.24108@smtp.wanadoo.fr>
In-Reply-To: <20020128221529.24108@smtp.wanadoo.fr>; from benh@kernel.crashing.org on Mon, Jan 28, 2002 at 11:15:28PM +0100
On Mon, Jan 28, 2002 at 11:15:28PM +0100, Benjamin Herrenschmidt wrote:
> >Well, get_user_pages is used by several parts of the kernel.
> >In the O_DIRECT/map_user_kiobuf case, we could end up asking
> >the disk controller to perform busmastering against the video
> >PCI device, which will probably explode somewhere down the chain.
>
> Well... not sure. I'd like this to be doable. I have worked
> on some high-end broadcast video stuffs in the past, and we
> did intensive use of direct bus master from the disk controller
> to the framebuffer linear aperture. Actually, we even controlled
you can do direct DMA to framebuffer on most sane hardware, yes. But
the kiobuf structure on 2.4 doesn't allow that, it only works with valid
'page structures' not physical addresses. This is valid for both rawio
and O_DIRECT. The MM part is the same for both of course.
Andrea
next prev parent reply other threads:[~2002-01-28 23:56 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-28 20:32 [PATCH?] Crash in 2.4.17/ptrace Daniel Jacobowitz
2002-01-28 21:03 ` Andrew Morton
2002-01-28 21:19 ` Daniel Jacobowitz
2002-01-28 21:29 ` Andrew Morton
2002-01-28 21:55 ` Alan Cox
2002-01-28 22:12 ` Andrew Morton
2002-01-29 22:59 ` [Linux-fbdev-devel] " James Simmons
2002-01-29 23:02 ` Andrew Morton
2002-01-30 0:13 ` James Simmons
2002-01-28 22:15 ` Benjamin Herrenschmidt
2002-01-28 23:57 ` Andrea Arcangeli [this message]
2002-01-28 23:54 ` Andrea Arcangeli
2002-01-29 5:35 ` Andrew Morton
2002-01-28 23:47 ` Andrea Arcangeli
2002-01-28 21:42 ` Andrew Morton
-- strict thread matches above, loose matches on Subject: below --
2002-01-28 21:33 Manfred Spraul
2002-01-28 22:05 ` Alan Cox
2002-01-28 22:07 ` Manfred Spraul
2002-01-28 22:26 ` Daniel Jacobowitz
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