From owner-freebsd-arm@FreeBSD.ORG Mon Mar 9 20:25:56 2015 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 6A8F91E6 for ; Mon, 9 Mar 2015 20:25:56 +0000 (UTC) Received: from phabric-backend.isc.freebsd.org (phabric-backend.isc.freebsd.org [IPv6:2001:4f8:3:ffe0:406a:0:50:2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 47C56752 for ; Mon, 9 Mar 2015 20:25:56 +0000 (UTC) Received: from phabric-backend.isc.freebsd.org (phabric-backend.isc.freebsd.org [127.0.1.5]) by phabric-backend.isc.freebsd.org (8.14.9/8.14.9) with ESMTP id t29KPtal081511 for ; Mon, 9 Mar 2015 20:25:55 GMT (envelope-from root@phabric-backend.isc.freebsd.org) Received: (from root@localhost) by phabric-backend.isc.freebsd.org (8.14.9/8.14.9/Submit) id t29KPtIj081509; Mon, 9 Mar 2015 20:25:55 GMT (envelope-from root) Date: Mon, 9 Mar 2015 20:25:55 +0000 To: freebsd-arm@freebsd.org From: "ian (Ian Lepore)" Subject: [Differential] [Commented On] D2017: Allow to disable alignment faults in the kernel configuration file Message-ID: X-Priority: 3 Thread-Topic: D2017: Allow to disable alignment faults in the kernel configuration file X-Herald-Rules: none X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-To: X-Phabricator-Cc: X-Phabricator-Cc: In-Reply-To: References: Thread-Index: M2IwYjY0ZDAxMWY3ZTNlM2Y4OWM0M2JjYjUzIFT+AdM= X-Phabricator-Sent-This-Message: Yes X-Mail-Transport-Agent: MetaMTA X-Auto-Response-Suppress: All X-Phabricator-Mail-Tags: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Mar 2015 20:25:56 -0000 ian added a comment. I disagree, adding this IS a big deal. As soon as we have a kernel out there that can support unaligned accesses, people will build userland apps that rely on that being true, and at that point we can't change it back without effectively breaking the ABI. Having the discussion about the implications of doing this is definitely something we should do up-front, because changing our minds will be somewhere between painful and impossible. (Look at the other things we've done without much thought, such as labeling an architecture "armv6" even though it's really armv7, then spending years trying to explain that armv6 means something different in FreeBSD.) REVISION DETAIL https://reviews.freebsd.org/D2017 To: zbb, ian, andrew, imp Cc: meloun-miracle-cz, freebsd-arm