From owner-freebsd-arm@FreeBSD.ORG Tue Mar 11 14:40:03 2014 Return-Path: Delivered-To: freebsd-arm@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 94CA0EB0 for ; Tue, 11 Mar 2014 14:40:03 +0000 (UTC) Received: from mho-01-ewr.mailhop.org (mho-03-ewr.mailhop.org [204.13.248.66]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 6A3D8D6F for ; Tue, 11 Mar 2014 14:40:03 +0000 (UTC) Received: from c-24-8-230-52.hsd1.co.comcast.net ([24.8.230.52] helo=damnhippie.dyndns.org) by mho-01-ewr.mailhop.org with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.72) (envelope-from ) id 1WNNqc-0005Ev-1b; Tue, 11 Mar 2014 14:40:02 +0000 Received: from [172.22.42.240] (revolution.hippie.lan [172.22.42.240]) by damnhippie.dyndns.org (8.14.3/8.14.3) with ESMTP id s2BEdxWD060316; Tue, 11 Mar 2014 08:39:59 -0600 (MDT) (envelope-from ian@FreeBSD.org) X-Mail-Handler: Dyn Standard SMTP by Dyn X-Originating-IP: 24.8.230.52 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/sendlabs/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX1+S1mo39IQYeSCpdktiv5xP Subject: Re: Updating the minimum armv6 requirement From: Ian Lepore To: Andrew Turner In-Reply-To: <20140311131945.01f4c9b2@bender> References: <20140311131945.01f4c9b2@bender> Content-Type: text/plain; charset="us-ascii" Date: Tue, 11 Mar 2014 08:39:58 -0600 Message-ID: <1394548798.1149.488.camel@revolution.hippie.lan> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 FreeBSD GNOME Team Port Content-Transfer-Encoding: 7bit Cc: freebsd-arm@FreeBSD.org X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 11 Mar 2014 14:40:03 -0000 On Tue, 2014-03-11 at 13:19 +1300, Andrew Turner wrote: > I've been looking at code that uses 64-bit C++ atomic operations on > armv6. These require the ldrexd and strexd instructions that are > present on armv6k. > > The problem is there is a mismatch between clang and binutils. Clang > thinks armv6k is an arm1136jf-s and sets the cpu in the asm output as > one. Binutils will see the cpu and think clang means an earlier armv6 > instruction set that lacks the above instructions. > > In this case both are correct as prior to the r1p0 release of the > arm1136jf-s core it was an armv6 core, and as of the r1p0 release it > became an armv6k core. > > All of this is uninteresting for FreeBSD as the only ARMv6 SoC we run > on appears to be the bcm2835, and maybe some Marvell parts. As the > bcm2835 is an arm1176jzf-s and we are unlikely to get a new ARMv6 port I > am suggesting we make this the minimum requirement. It appears NetBSD > has the same requirement as clang will set the cpu to arm1176jzf-s when > building for NetBSD and armv6. > > My proposal is to have the same CPU requirement as NetBSD for armv6. Is > anyone working on an SoC that would be affected by this? > > Andrew I think this is fine. I thought we already had a rule that armv6k was the minimum. If we just need the compiler to emit a different .cpu directive to keep the assembler happy, that should be fine. Since we don't support the pre-'k' variants of armv6, there should be no conflicts. -- Ia