From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:36849)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <alex.williamson@redhat.com>) id 1VAMBH-0002Di-SG
	for qemu-devel@nongnu.org; Fri, 16 Aug 2013 11:43:21 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <alex.williamson@redhat.com>) id 1VAMBB-0002aF-Uc
	for qemu-devel@nongnu.org; Fri, 16 Aug 2013 11:43:15 -0400
Message-ID: <1376667787.28796.1.camel@ul30vt.home>
From: Alex Williamson <alex.williamson@redhat.com>
Date: Fri, 16 Aug 2013 09:43:07 -0600
In-Reply-To: <1376667453.28796.0.camel@ul30vt.home>
References: <20130816124915.12577.72732.stgit@bling.home>
	<520E44CA.6050205@twiddle.net> <1376667453.28796.0.camel@ul30vt.home>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v2] exec: Fix non-power-of-2 sized accesses
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Richard Henderson <rth@twiddle.net>
Cc: lersek@redhat.com, qemu-devel@nongnu.org, qemu-stable@nongnu.org

On Fri, 2013-08-16 at 09:37 -0600, Alex Williamson wrote:
> On Fri, 2013-08-16 at 08:27 -0700, Richard Henderson wrote:
> > On 08/16/2013 05:50 AM, Alex Williamson wrote:
> > > +    /* Size must be a power of 2 */
> > > +    if (l & (l - 1)) {
> > > +        while (l & (access_size_max - 1)) {
> > > +            access_size_max >>= 1;
> > > +        }
> > > +    }
> > > +
> > 
> > Why the loop at all?  x & -x extracts the lsb of x.
> 
> l = 5, we want 4, not 1.  Thanks,

Which is not what my patch does either :-\