Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758253Ab1DAVvW (ORCPT ); Fri, 1 Apr 2011 17:51:22 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:62894 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757529Ab1DAVvU convert rfc822-to-8bit (ORCPT ); Fri, 1 Apr 2011 17:51:20 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=C3lzhCt6FP70BqP7oIu4cZ0FqlqgotwTyevWPIilseZWvfLQEZtSIAwIsAWPyzh04w LRwwBEImZOuoCZiuiiZhhdqTiqudxZG3i5SApQqTmXgEqOP+0tVp4Vfpee0ZtzgPhHNi O9r8nDZLR9yHiIrDVypZXd+a26aZXZBpfcZDc= MIME-Version: 1.0 In-Reply-To: <201104012332.24319.arnd@arndb.de> References: <201104011659.40443.arnd@arndb.de> <87vcyxllub.fsf@ti.com> <201104012332.24319.arnd@arndb.de> Date: Fri, 1 Apr 2011 22:51:19 +0100 X-Google-Sender-Auth: Zu5kIHcwuGP4RyIwCiTSoKzWoG4 Message-ID: Subject: Re: [GIT PULL] omap changes for v2.6.39 merge window From: Catalin Marinas To: Arnd Bergmann Cc: "linux-arm-kernel@lists.infradead.org" , Kevin Hilman , "david@lang.hm" , Russell King - ARM Linux , Nicolas Pitre , Tony Lindgren , Catalin Marinas , lkml , Thomas Gleixner , "H. Peter Anvin" , Ingo Molnar , "linux-omap@vger.kernel.org" , Linus Torvalds , David Brown , Detlef Vollmann Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2624 Lines: 56 On Friday, 1 April 2011, Arnd Bergmann wrote: > On Friday 01 April 2011 23:10:04 Kevin Hilman wrote: >> Arnd Bergmann writes: >> >> > On Friday 01 April 2011, Detlef Vollmann wrote: >> >> On 04/01/11 15:54, Arnd Bergmann wrote: >> > >> >> > 9. All interesting work is going into a handful of platforms, all of which >> >> >     are ARMv7 based. >> >> Define interesting. >> > >> > The ones that are causing the churn that we're talking about. >> > Platforms that have been working forever and only need to get >> > the occasional bug fix are boring, i.e. not the problem. >> >> I'm not sure I follow the ARMv7-only thinking either. >> >> Picking ARMv7 only would be a good way to avoid part of the problem, but >> IMO, it doesn't really address the root causes.  Part of the ugliness of >> the platform-specific hackery (and the "churn" to clean some of it up) >> is precisely due to support for multiple ARM architecture versions, and >> the various SoCs in a family that use them.  For example, linux-omap >> supports OMAP1 (ARMv5), OMAP2 (ARMv6), OMAP3 (ARMv7) and OMAP4 (ARMv7 >> SMP), and OMAP2/3/4 in a single binary. >> >> Also, since we've only very recently got to the point of being able to >> support ARMv6 + ARMv7 UP & SMP in the same kernel, making a decision now >> that only ARMv7 is important seems like a step backwards.  If the >> ultimate goal is getting to a point where we have infrastrucure that can >> be cross-SoC, surely this same infrastrucure should support multiple ARM >> architecture revisions. > > Yes, forget about the ARMv7 part of my proposal, that was not a main point. > > If we decide to have a new clean platform variant the way I suggested, > it would be nice to support all machines in a single kernel binary, > and at least v6+v7 is a solved problem. > > Supporting a second kernel binary up to v5 with the same source is also > simple, as would be big-endian/little-endian variants, or thumb2/arm variants. > We might not want to do all combinations from the start though, and I would > choose ARMv6/v7-thumb2-le simply because that's what Linaro is focusing > on. The idea is to start with a clearly defined set, but write the code > in a way that makes it possible to extend in other directions. Thumb-2 is ARMv7 only. If you want a v6+v7 binary it would need to be compiled to ARM. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/