From: Sjoerd Simons <sjoerd@luon.net>
To: sparclinux@vger.kernel.org
Subject: Re: ioct32 bit compatibilty questions
Date: Sat, 20 Nov 2004 15:47:08 +0000 [thread overview]
Message-ID: <20041120154708.GA17467@spring.luon.net> (raw)
In-Reply-To: <20041111110024.GA8836@spring.luon.net>
On Thu, Nov 11, 2004 at 11:04:14AM -0800, David S. Miller wrote:
> On Thu, 11 Nov 2004 12:00:24 +0100
> sjoerd@spring.luon.net (Sjoerd Simons) wrote:
>
> > After some debugging it seems that some alsa ioctl have a pointer to a
> > userspace pointer in their argument struct. When doing a copy_to_user in the
> > native ioctl to that address (thus directly to the 32bit userspace program
> > while get_fs() = KERNEL_DS), the machine just hangs. Is this something
> > that can't be done on sparc64 ?
>
> That's right, this action is illegal and will hang the machine.
> Unfortunately, on x86_64 this happens to work and that appears
> to be where most of the ioctl32 compat stuff gets tested and
> developed.
>
> If get_fs() = KERNEL_DS all "user" pointers are expected to be in
> kernel space and thus access to real user addresses will fail.
Finally had time to finish the patch. With alsaplayer there is now music out of
my U5's speakers :) Unfortunately there is some distortion. But that is
probably the card driver itself. A friend of mine told me he also had
distortions with alsa's oss emulation on an U5..
Patch attached against linux 2.6.9. I haven't done a lot of kernel hacking, so
any comments are very welcome!
Also for the people interested i've put a patch against alsa cvs in the alsa bug
tracking system so they can have a look at it too.
Sjoerd
--
You can no more win a war than you can win an earthquake.
-- Jeannette Rankin
next prev parent reply other threads:[~2004-11-20 15:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-11 11:00 ioct32 bit compatibilty questions Sjoerd Simons
2004-11-11 19:04 ` David S. Miller
2004-11-20 15:47 ` Sjoerd Simons [this message]
2004-11-20 15:50 ` Sjoerd Simons
2004-11-21 10:41 ` Jeremy Huddleston
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