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[209.132.180.67]) by mx.google.com with ESMTP id t12si7685365plq.190.2018.11.28.08.10.16; Wed, 28 Nov 2018 08:10:55 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@xenosoft.de header.s=strato-dkim-0002 header.b=Dqsn1Zay; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728914AbeK2DKC (ORCPT + 99 others); Wed, 28 Nov 2018 22:10:02 -0500 Received: from mo4-p01-ob.smtp.rzone.de ([85.215.255.50]:36615 "EHLO mo4-p01-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727979AbeK2DKB (ORCPT ); Wed, 28 Nov 2018 22:10:01 -0500 X-Greylist: delayed 708 seconds by postgrey-1.27 at vger.kernel.org; Wed, 28 Nov 2018 22:10:00 EST DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1543421271; s=strato-dkim-0002; d=xenosoft.de; h=In-Reply-To:Date:Message-ID:From:References:Cc:To:Subject: X-RZG-CLASS-ID:X-RZG-AUTH:From:Subject:Sender; bh=7xS2QcB97L9QI4n5R/5DRuYEud3Vh5VKc9tcNvItCtM=; b=Dqsn1ZayszGY5k4h967SS8hxLLStPdjSSGDinTl6xh2V2f0oq/Y7mx6oVvFBonPPy4 IEZcjaS0HhXx3wmGlKOBajMDhbiU58dujubG+dvRvmq4hYEwndqt+40smnpfcHxvWD2+ p98dLzfFnoU65rOqPwtP17wR6+HpmfWONwzO+mPlcLycbJmKqlJkqG+4IS2sqWeAQNPq 8UYQwliwf1exS8zXYKMK2r3YH47mRmDbTlt/5cBYOhBxE+EbyEL4POCYpsicxVtZPdV3 bpqSd7qOQFYeIM9STuzMxoq8xXIk+cVX20gwIU/dWstEmYzOsa0FATW4OaP3Lgd6SJJz 3vhQ== X-RZG-AUTH: ":L2QefEenb+UdBJSdRCXu93KJ1bmSGnhMdmOod1DhGM4l4Hio94KKxRySfLxnHfJ+Dkjp5G5MdirQj0WG7CkIise/x75IsWntOVj9qPtpgydF" X-RZG-CLASS-ID: mo00 Received: from [IPv6:2a02:8109:a400:162c:74d7:2770:613:8ba4] by smtp.strato.de (RZmta 44.6 AUTH) with ESMTPSA id 404b20uASFtU7KR (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (curve secp521r1 with 521 ECDH bits, eq. 15360 bits RSA)) (Client did not present a certificate); Wed, 28 Nov 2018 16:55:30 +0100 (CET) Subject: Re: use generic DMA mapping code in powerpc V4 To: Michael Ellerman , Christoph Hellwig , Benjamin Herrenschmidt , Paul Mackerras Cc: linux-arch@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20181114082314.8965-1-hch@lst.de> <20181127074253.GB30186@lst.de> <87zhttfonk.fsf@concordia.ellerman.id.au> From: Christian Zigotzky Message-ID: <535776df-dea3-eb26-6bf3-83f225e977df@xenosoft.de> Date: Wed, 28 Nov 2018 16:55:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <87zhttfonk.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: de-DE Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28 November 2018 at 12:05PM, Michael Ellerman wrote: > Nothing specific yet. > > I'm a bit worried it might break one of the many old obscure platforms > we have that aren't well tested. > Please don't apply the new DMA mapping code if you don't be sure if it works on all supported PowerPC machines. Is the new DMA mapping code really necessary? It's not really nice, to rewrote code if the old code works perfect. We must not forget, that we work for the end users. Does the end user have advantages with this new code? Is it faster? The old code works without any problems. I am also worried about this code. How can I test this new DMA mapping code? Thanks