From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Metcalf Subject: Re: bit fields && data tearing Date: Mon, 8 Sep 2014 16:45:59 -0400 Message-ID: <540E1587.3060108@tilera.com> References: <21512.10628.412205.873477@gargle.gargle.HOWL> <20140904090952.GW17454@tucnak.redhat.com> <540859EC.5000407@hurleysoftware.com> <20140904175044.4697aee4@alan.etchedpixels.co.uk> <5408C0AB.6050801@hurleysoftware.com> <20140905001751.GL5001@linux.vnet.ibm.com> <1409883098.5078.14.camel@jarvis.lan> <5409243C.4080704@hurleysoftware.com> <20140905040645.GO5001@linux.vnet.ibm.com> <1410066442.12512.13.camel@jarvis.lan> <20140907162146.GK5001@linux.vnet.ibm.com> <1410116687.2027.19.camel@jarvis.lan> <540CC305.8010407@hurleysoftware.com> <1410155407.2027.29.camel@jarvis.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1410155407.2027.29.camel@jarvis.lan> Sender: linux-ia64-owner@vger.kernel.org To: James Bottomley , Peter Hurley Cc: paulmck@linux.vnet.ibm.com, "H. Peter Anvin" , One Thousand Gnomes , Jakub Jelinek , Mikael Pettersson , Benjamin Herrenschmidt , Richard Henderson , Oleg Nesterov , Miroslav Franc , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Tony Luck , linux-ia64@vger.kernel.org List-Id: linux-arch.vger.kernel.org On 9/8/2014 1:50 AM, James Bottomley wrote: > Actual alignment is pretty irrelevant. That's why all architectures > which require alignment also have to implement misaligned traps ... this > is a fundamental requirement of the networking code, for instance. Can you clarify what you think the requirement is? The tile architecture doesn't support misaligned load/store in general, but we do support it for userspace (using a nifty JIT approach with a direct-map hash table kept in userspace), and also for get_user/put_user. But that's it, and, the networking subsystem works fine for us. Occasionally we report bugs for driver code that doesn't use the get_unaligned_xxx() macros and friends, and our fixes are generally taken upstream. -- Chris Metcalf, Tilera Corp. http://www.tilera.com From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Metcalf Date: Mon, 08 Sep 2014 20:45:59 +0000 Subject: Re: bit fields && data tearing Message-Id: <540E1587.3060108@tilera.com> List-Id: References: <21512.10628.412205.873477@gargle.gargle.HOWL> <20140904090952.GW17454@tucnak.redhat.com> <540859EC.5000407@hurleysoftware.com> <20140904175044.4697aee4@alan.etchedpixels.co.uk> <5408C0AB.6050801@hurleysoftware.com> <20140905001751.GL5001@linux.vnet.ibm.com> <1409883098.5078.14.camel@jarvis.lan> <5409243C.4080704@hurleysoftware.com> <20140905040645.GO5001@linux.vnet.ibm.com> <1410066442.12512.13.camel@jarvis.lan> <20140907162146.GK5001@linux.vnet.ibm.com> <1410116687.2027.19.camel@jarvis.lan> <540CC305.8010407@hurleysoftware.com> <1410155407.2027.29.camel@jarvis.lan> In-Reply-To: <1410155407.2027.29.camel@jarvis.lan> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: James Bottomley , Peter Hurley Cc: paulmck@linux.vnet.ibm.com, "H. Peter Anvin" , One Thousand Gnomes , Jakub Jelinek , Mikael Pettersson , Benjamin Herrenschmidt , Richard Henderson , Oleg Nesterov , Miroslav Franc , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Tony Luck , linux-ia64@vger.kernel.org On 9/8/2014 1:50 AM, James Bottomley wrote: > Actual alignment is pretty irrelevant. That's why all architectures > which require alignment also have to implement misaligned traps ... this > is a fundamental requirement of the networking code, for instance. Can you clarify what you think the requirement is? The tile architecture doesn't support misaligned load/store in general, but we do support it for userspace (using a nifty JIT approach with a direct-map hash table kept in userspace), and also for get_user/put_user. But that's it, and, the networking subsystem works fine for us. Occasionally we report bugs for driver code that doesn't use the get_unaligned_xxx() macros and friends, and our fixes are generally taken upstream. -- Chris Metcalf, Tilera Corp. http://www.tilera.com From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from USMAMAIL.TILERA.COM (usmamail.tilera.com [12.216.194.151]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 05B331A0121 for ; Tue, 9 Sep 2014 06:51:33 +1000 (EST) Message-ID: <540E1587.3060108@tilera.com> Date: Mon, 8 Sep 2014 16:45:59 -0400 From: Chris Metcalf MIME-Version: 1.0 To: James Bottomley , Peter Hurley Subject: Re: bit fields && data tearing References: <21512.10628.412205.873477@gargle.gargle.HOWL> <20140904090952.GW17454@tucnak.redhat.com> <540859EC.5000407@hurleysoftware.com> <20140904175044.4697aee4@alan.etchedpixels.co.uk> <5408C0AB.6050801@hurleysoftware.com> <20140905001751.GL5001@linux.vnet.ibm.com> <1409883098.5078.14.camel@jarvis.lan> <5409243C.4080704@hurleysoftware.com> <20140905040645.GO5001@linux.vnet.ibm.com> <1410066442.12512.13.camel@jarvis.lan> <20140907162146.GK5001@linux.vnet.ibm.com> <1410116687.2027.19.camel@jarvis.lan> <540CC305.8010407@hurleysoftware.com> <1410155407.2027.29.camel@jarvis.lan> In-Reply-To: <1410155407.2027.29.camel@jarvis.lan> Content-Type: text/plain; charset="UTF-8"; format=flowed Cc: Jakub Jelinek , One Thousand Gnomes , linux-arch@vger.kernel.org, linux-ia64@vger.kernel.org, Mikael Pettersson , Oleg Nesterov , linux-kernel@vger.kernel.org, Tony Luck , Paul Mackerras , "H. Peter Anvin" , paulmck@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, Miroslav Franc , Richard Henderson List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 9/8/2014 1:50 AM, James Bottomley wrote: > Actual alignment is pretty irrelevant. That's why all architectures > which require alignment also have to implement misaligned traps ... this > is a fundamental requirement of the networking code, for instance. Can you clarify what you think the requirement is? The tile architecture doesn't support misaligned load/store in general, but we do support it for userspace (using a nifty JIT approach with a direct-map hash table kept in userspace), and also for get_user/put_user. But that's it, and, the networking subsystem works fine for us. Occasionally we report bugs for driver code that doesn't use the get_unaligned_xxx() macros and friends, and our fixes are generally taken upstream. -- Chris Metcalf, Tilera Corp. http://www.tilera.com From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754683AbaIHUqE (ORCPT ); Mon, 8 Sep 2014 16:46:04 -0400 Received: from usmamail.tilera.com ([12.216.194.151]:49754 "EHLO USMAMAIL.TILERA.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754122AbaIHUqA (ORCPT ); Mon, 8 Sep 2014 16:46:00 -0400 X-CheckPoint: {540E1587-50-2100090A-C0000000} Message-ID: <540E1587.3060108@tilera.com> Date: Mon, 8 Sep 2014 16:45:59 -0400 From: Chris Metcalf User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: James Bottomley , Peter Hurley CC: , "H. Peter Anvin" , One Thousand Gnomes , Jakub Jelinek , Mikael Pettersson , Benjamin Herrenschmidt , Richard Henderson , Oleg Nesterov , Miroslav Franc , Paul Mackerras , , , , Tony Luck , Subject: Re: bit fields && data tearing References: <21512.10628.412205.873477@gargle.gargle.HOWL> <20140904090952.GW17454@tucnak.redhat.com> <540859EC.5000407@hurleysoftware.com> <20140904175044.4697aee4@alan.etchedpixels.co.uk> <5408C0AB.6050801@hurleysoftware.com> <20140905001751.GL5001@linux.vnet.ibm.com> <1409883098.5078.14.camel@jarvis.lan> <5409243C.4080704@hurleysoftware.com> <20140905040645.GO5001@linux.vnet.ibm.com> <1410066442.12512.13.camel@jarvis.lan> <20140907162146.GK5001@linux.vnet.ibm.com> <1410116687.2027.19.camel@jarvis.lan> <540CC305.8010407@hurleysoftware.com> <1410155407.2027.29.camel@jarvis.lan> In-Reply-To: <1410155407.2027.29.camel@jarvis.lan> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.9.0.23] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/8/2014 1:50 AM, James Bottomley wrote: > Actual alignment is pretty irrelevant. That's why all architectures > which require alignment also have to implement misaligned traps ... this > is a fundamental requirement of the networking code, for instance. Can you clarify what you think the requirement is? The tile architecture doesn't support misaligned load/store in general, but we do support it for userspace (using a nifty JIT approach with a direct-map hash table kept in userspace), and also for get_user/put_user. But that's it, and, the networking subsystem works fine for us. Occasionally we report bugs for driver code that doesn't use the get_unaligned_xxx() macros and friends, and our fixes are generally taken upstream. -- Chris Metcalf, Tilera Corp. http://www.tilera.com