From owner-freebsd-arm@freebsd.org Thu Mar 16 18:07:43 2017 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9C264D0F1BE for ; Thu, 16 Mar 2017 18:07:43 +0000 (UTC) (envelope-from sylvain@sylvaingarrigues.com) Received: from mail-wr0-x244.google.com (mail-wr0-x244.google.com [IPv6:2a00:1450:400c:c0c::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 2E79C154F for ; Thu, 16 Mar 2017 18:07:42 +0000 (UTC) (envelope-from sylvain@sylvaingarrigues.com) Received: by mail-wr0-x244.google.com with SMTP id u48so6887918wrc.1 for ; Thu, 16 Mar 2017 11:07:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sylvaingarrigues-com.20150623.gappssmtp.com; s=20150623; h=from:mime-version:subject:date:references:to:in-reply-to:message-id; bh=hT6Y7Pf8ulvJfUWCM1txj+cMxt564LmaewpT/ol6gHo=; b=xNHA5HW3O42TocomDzbkWt006Gipr09drWRpKu0uJ73PNBgQZZUdM42rPqppuxeeeI fNtArR6kQJbppv65zjyQJGdEcy75AUhYdYQkEsBHsB/u7W2asmBhOat45lRer/+g5OPl Bn+A8arLQraZz213by2QNe9Ki4IWMN+e18zX1g/6i6lVDHXDZkxXdGU2bgO4XC6jB7eC 35Onq8uC2tSPi3eO2atd3zgBTGkn+GYup0Lo1Nn7eQoAErSyetGS0wr+rwWE7XaS4j/W kilGXMuKEr3wqICMe9mabJa5pR0b9aOwaNXv59qy29DEIaxxoTw0dDalgrOjrkVCTf2j 5OTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:mime-version:subject:date:references:to :in-reply-to:message-id; bh=hT6Y7Pf8ulvJfUWCM1txj+cMxt564LmaewpT/ol6gHo=; b=SY/xnLdf0oF3fJkkPjPFwcrYP8WVknivVsViA3kYEydDppL/J4pi5CbnduKydiUveY JpVPafmUQSGC1ho2WiDUStDyFrdoGzZJAXMwBLr0AYoI4zhNMWlnuvROYEdHlgzZrxQL TLzL6UgGSOqhyHfwMAxvR1buiBrBuk7OKLUPEECvtlQPyx8hiW0l+bGcXIZyH0Xf3f0d MY7oOS60g6/xbHIfvZ/neYrpzomu8JRu5J+xDWp9NsUXdla6fNxPSG26HYvGTk8j8mt2 Ed/fUz6IshFRn3tAbM/EH19ydC9ySSYnRTrF+GiNF+J3LY35ODN2ub4308SACkGAPfcr 64wQ== X-Gm-Message-State: AFeK/H2CCyZ+hW9l6rDW63m7WmVC0TFvCj+logcm9gGdrIHwnb71hKyalDMoPQ9zDg9ZOQ== X-Received: by 10.223.156.2 with SMTP id f2mr2618584wrc.176.1489687661256; Thu, 16 Mar 2017 11:07:41 -0700 (PDT) Received: from [172.21.11.111] ([158.255.96.238]) by smtp.gmail.com with ESMTPSA id k43sm7042767wrk.42.2017.03.16.11.07.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 Mar 2017 11:07:40 -0700 (PDT) From: Sylvain Garrigues Mime-Version: 1.0 (Mac OS X Mail 10.2 \(3259\)) Subject: Re: Is CPUTYPE=cortex-A7 supposed to work? Date: Thu, 16 Mar 2017 19:07:39 +0100 References: <871suc3nv8.fsf@news-spur.riddles.org.uk> <8737ely05c.fsf@news-spur.riddles.org.uk> <87wpbxw3yd.fsf@news-spur.riddles.org.uk> <79EBD44B-2C2D-4394-A90C-DF494A049F20@dsl-only.net> <674facba-68cd-8ce1-887a-1ef3c51520bc@freebsd.org> <87pohh2n3c.fsf@news-spur.riddles.org.uk> To: Andrew Gierth , mmel@freebsd.org, freebsd-arm In-Reply-To: <87pohh2n3c.fsf@news-spur.riddles.org.uk> Message-Id: X-Mailer: Apple Mail (2.3259) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Mar 2017 18:07:43 -0000 > Le 16 mars 2017 =C3=A0 18:27, Andrew Gierth = a =C3=A9crit : >=20 > tl/dr: building without CPUTYPE is a workaround that simply reduces = both > the chance and severity of failure; building with CPUTYPE currently > breaks almost everything, but with a probability that varies wildly > depending on what the application does. Got it now, thank you both Andrew and Michal. I can=E2=80=99t imagine = how lucky we are to have you guys analyze these behaviors so quickly and = accurately.=20 My conclusion of these discussions seems to be: - Andrew, you proposed a kernel patch which fixes / handles the saving = and restoring of FP registers during signal (kernel side). It seems it = greatly reduces the failure probability by allowing applications to have = FPU instructions in signal handlers. But it breaks ABI. - Michal, you mentioned you=E2=80=99d like to fix this in a way that = doesn=E2=80=99t break ABI, and that: * the "VFP part of kernel <-> userland interaction is broken from = day 1 =C2=BB <<=3D=3D was it just this signal part which was broken? * and "the struct fpreg is also wrong and I'm not sure if or how we = can to fix this in compatible way =C2=BB <<=3D=3D Andrew=E2=80=99s patch = doesn=E2=80=99t fix this right? Is this a serious problem doctor? What = are the symptoms? So what are you guys gonna do about all this, are you going to address = these issues, are you going to break the ABI in 12-CURRENT? Can wait to = hear about the next steps, the suspense is terrible :-)=