From: Linus Torvalds <torvalds@transmeta.com>
To: Kanoj Sarcar <kanoj@google.engr.sgi.com>
Cc: Andrea Arcangeli <andrea@suse.de>,
alan@lxorguk.ukuu.org.uk, sct@redhat.com,
Gerhard.Wichert@pdb.siemens.de, Winfried.Gerhard@pdb.siemens.de,
linux-kernel@vger.rutgers.edu, linux-mm@kvack.org
Subject: Re: [bigmem-patch] 4GB with Linux on IA32
Date: Mon, 16 Aug 1999 23:41:50 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.10.9908162339360.1048-100000@penguin.transmeta.com> (raw)
In-Reply-To: <199908170637.XAA81444@google.engr.sgi.com>
On Mon, 16 Aug 1999, Kanoj Sarcar wrote:
>
> As I pointed out before, I don't think rawio is the only case which
> breaks.
>
> I will give you one example of the type of cases that I am talking about.
> In drivers/char/bttv.c, VIDIOCSFBUF ioctl seems to be setting the "vidadr"
> to a kernel virtual address from the physical address present in the
> user's pte. This will not work for bigmem pages.
This is exactly why I have always been adamant that people should NOT do
direct IO and try to walk the page tables. But people have ignored me, and
quite frankly, those drivers should just be broken. The painful part is
finding out which of them do it, but once done they should just be broken
wrt bigmem, no questions asked.
Linus
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next prev parent reply other threads:[~1999-08-17 6:41 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-08-16 16:29 Andrea Arcangeli
1999-08-16 16:48 ` Matthew Wilcox
1999-08-16 17:19 ` Andrea Arcangeli
1999-08-16 18:43 ` Kanoj Sarcar
1999-08-16 19:43 ` Alan Cox
1999-08-16 20:54 ` Andrea Arcangeli
1999-08-16 22:47 ` Andrea Arcangeli
1999-08-16 23:26 ` Andrea Arcangeli
1999-08-16 23:39 ` Kanoj Sarcar
1999-08-17 0:10 ` Andrea Arcangeli
1999-08-17 6:37 ` Kanoj Sarcar
1999-08-17 6:41 ` Linus Torvalds [this message]
1999-08-17 6:50 ` Kanoj Sarcar
1999-08-17 7:03 ` Linus Torvalds
1999-08-17 7:23 ` Linus Torvalds
1999-08-17 11:39 ` Alan Cox
1999-08-26 16:27 ` Andrea Arcangeli
1999-08-17 11:46 ` Alan Cox
1999-08-17 14:26 ` Andrea Arcangeli
1999-08-17 6:39 ` Linus Torvalds
1999-08-17 12:40 ` Andrea Arcangeli
1999-08-17 6:29 ` Linus Torvalds
1999-08-17 12:37 ` Andrea Arcangeli
1999-08-17 14:04 ` Andrea Arcangeli
1999-08-17 8:52 ` Jakub Jelinek
1999-08-17 9:13 ` Pavel Machek
1999-08-18 14:08 ` Andrea Arcangeli
1999-08-19 12:20 ` Andrea Arcangeli
1999-08-16 23:28 ` Kanoj Sarcar
1999-08-16 23:49 ` Andrea Arcangeli
1999-08-17 6:29 ` David S. Miller
1999-08-17 12:38 ` Andrea Arcangeli
1999-08-17 0:17 ` Andrea Arcangeli
1999-08-19 13:33 ` Thierry Vignaud
1999-08-19 16:49 ` Stephen C. Tweedie
1999-08-20 7:35 ` Thierry Vignaud
1999-08-20 9:55 ` Alan Cox
1999-08-20 18:25 ` Linus Torvalds
1999-08-16 20:34 ` Andrea Arcangeli
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