From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id AEA1A139083 for ; Sun, 3 Dec 2017 07:40:39 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id EFFC6E0F8E; Sun, 3 Dec 2017 07:40:32 +0000 (UTC) Received: from smtp.gentoo.org (smtp.gentoo.org [140.211.166.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 84DC2E0F7B for ; Sun, 3 Dec 2017 07:40:32 +0000 (UTC) Received: from mail-wm0-f48.google.com (mail-wm0-f48.google.com [74.125.82.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: floppym) by smtp.gentoo.org (Postfix) with ESMTPSA id 4035433BF43 for ; Sun, 3 Dec 2017 07:40:31 +0000 (UTC) Received: by mail-wm0-f48.google.com with SMTP id g75so798007wme.0 for ; Sat, 02 Dec 2017 23:40:31 -0800 (PST) X-Gm-Message-State: AKGB3mKt3ouzl4Fz2XejUTc8zIY/k5t9Ua+ONGQDwmSZHcDtlLOLpOYq deM1ZpvwV/E5/hGhVzj+a+zwz2x2T7KqzAmslhE= X-Google-Smtp-Source: AGs4zMZS89aIlNHopFZbbRfZb/w+QyrhoenIWAAJNC9TX/cd8NZuC/yKGtMPYq/eLBqN1OK0wzEUZtJhrO8uq0Egkas= X-Received: by 10.28.174.133 with SMTP id x127mr4353715wme.107.1512286828423; Sat, 02 Dec 2017 23:40:28 -0800 (PST) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Received: by 10.223.136.74 with HTTP; Sat, 2 Dec 2017 23:40:07 -0800 (PST) In-Reply-To: References: From: Mike Gilbert Date: Sun, 3 Dec 2017 02:40:07 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [gentoo-user] CFLAGS for both AMD64 and Intel? To: gentoo-user@lists.gentoo.org Content-Type: text/plain; charset="UTF-8" X-Archives-Salt: 2e786660-090b-406a-884e-a33a442343fa X-Archives-Hash: b9e61f39048aad7866e334bb7aaa68f0 On Sun, Dec 3, 2017 at 2:23 AM, Manuel McLure wrote: > Here's the situation. I have a system that's been running for many years > with an Athlon 5050e processor. The system is built with > > CFLAGS="-march=k8-sse3 -O2 -pipe -msse3" > CPU_FLAGS_X86="3dnow 3dnowext mmx mmxext sse sse2 sse3" > > I have the possibility of upgrading the system to a first-generation Intel > Core i5 which should give a nice speed boost, but of course the Intel chip > doesn't understand 3dnow or 3dnowext, so I'll have to do a system rebuild > before I switch out the motherboard/processor. It seems pretty obvious that > I have to take "3dnow 3dnowext" out of CPU_FLAGS_X86, but what CFLAGS would > be recommended for a system that will still run with the AMD processor but > won't fall over when I switch to the Intel processor? Once I have the Intel > in place I can rebuild with options more suited for that chip, but I want to > make sure I don't end up in a catch-22 situation. I would go with just "-O2 -pipe" for maximum compatibility. Remove the -march option altogether, and add it back once the system is running on the Intel chip.