Date: Thu, 6 Dec 2007 13:43:41 -0800
To: Michael Buesch <mb@bu3sch.de>
Cc: David Miller <davem@davemloft.net>, shaddy_baddah@hotmail.com,
	linux-wireless@vger.kernel.org, dsd@gentoo.org,
	johannes@sipsolutions.net
Subject: Re: zd1211rw (2.6.22 sparc64): unaligned access (do_rx)
Message-ID: <20071206214341.GA6821@bougret.hpl.hp.com> (sfid-20071206_214402_135467_E2AACAD3)
Reply-To: jt@hpl.hp.com
References: <20071204000138.GA1363@bougret.hpl.hp.com> <20071205.183628.211180882.davem@davemloft.net> <20071206212525.GA6509@bougret.hpl.hp.com> <200712062233.18634.mb@bu3sch.de>
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In-Reply-To: <200712062233.18634.mb@bu3sch.de>
From: Jean Tourrilhes <jt@hpl.hp.com>
Sender: linux-wireless-owner@vger.kernel.org

On Thu, Dec 06, 2007 at 10:33:18PM +0100, Michael Buesch wrote:
> On Thursday 06 December 2007 22:25:25 Jean Tourrilhes wrote:
> > On Wed, Dec 05, 2007 at 06:36:28PM -0800, David Miller wrote:
> > > From: Jean Tourrilhes <jt@hpl.hp.com>
> > > Date: Wed, 5 Dec 2007 13:56:00 -0800
> > > 
> > > > 	Personally, I was under the impression that in userspace libc
> > > > trap unaligned access and make them work. I mean, this code was tested
> > > > on other 64/32 bit platforms (PPC, AMD-64, PS3) and was working there,
> > > > so this seems to be specific to your platform.
> > > 
> > > None of those listed platforms trap on unaligned accesses like sparc
> > > does.
> > 
> 
> > 	Now, I'm wondering how to deal with unaligned access in
> > userspace. If you get data from hardware or the network, you can not
> > guarantee that everything will always be aligned, so we need a way to
> > deal with it.
> > 	In the kernel, we have get_unaligned(). I wonder what's the
> > equivalent in userspace.
> 
> Userspace handles this transparently through fault traps.

	This is exactly what I was assuming. On the SPARC, in this
instance, it did not (check back earlier in this discussion).

> Greetings Michael.

	Regards,

	Jean