From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 2 Jul 2014 18:01:41 +0100 Subject: Android and compatibility with deprecated armv7 instructions In-Reply-To: <20140702163923.GJ410@sirena.org.uk> References: <20140701234800.GA23577@sirena.org.uk> <20140702100133.GE18731@arm.com> <20140702163923.GJ410@sirena.org.uk> Message-ID: <20140702170141.GH24879@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jul 02, 2014 at 05:39:23PM +0100, Mark Brown wrote: > On Wed, Jul 02, 2014 at 11:01:33AM +0100, Will Deacon wrote: > > > (1) The hardware doesn't have the instruction at all. If we start > > emulating it, then we'll always have to emulate it and it doesn't > > encourage software migration. > > That's what the logging other architectures did in similar situations > was intended to help address - even if people don't care about the > performance impact having loud complaints in the logs tends to cause > some useful subset of users to report it as a problem. I don't think logging something to dmesg is going to make a blind bit of difference on an Android device. Maybe we could get SWP emulation to request access to the users contacts and send everybody a text message each time they issue the instruction? Seriously though, nothing causes loud complaints like a SIGILL. This thread is evidence of that. Will