From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752641AbcH3Ggz (ORCPT ); Tue, 30 Aug 2016 02:36:55 -0400 Received: from verein.lst.de ([213.95.11.211]:33407 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750697AbcH3Ggy (ORCPT ); Tue, 30 Aug 2016 02:36:54 -0400 Date: Tue, 30 Aug 2016 08:36:51 +0200 From: Christoph Hellwig To: Andy Lutomirski Cc: Keith Busch , Andy Lutomirski , Jens Axboe , linux-nvme@lists.infradead.org, Christoph Hellwig , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/3] nvme: Pass pointers, not dma addresses, to nvme_get/set_features() Message-ID: <20160830063651.GA32323@lst.de> References: <2756c572e066ed91a41e35568a4d9346e47d6b42.1472462539.git.luto@kernel.org> <20160829162735.GD19986@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 29, 2016 at 04:20:43PM -0700, Andy Lutomirski wrote: > The "Set Features" command (section 5.15) Figure 103 says: > > If using PRPs, this field shall not be a pointer to a PRP List as the > data buffer may not cross more than one page boundary. If no data > structure is used as part of the specified feature, then this field is > not used. > > Does the Linux driver use PRPs? The Linux PCIe driver always uses PRPs - and for admin command only Fabrics can use SGLs anyway. > Do we need to worry about kmalloc > returning a buffer that spans a 4k boundary but does not span a Linux > page boundary? Isn't kmalloc supposed to return naturally aligned buffers?