Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753542AbaFJVdg (ORCPT ); Tue, 10 Jun 2014 17:33:36 -0400 Received: from mga11.intel.com ([192.55.52.93]:18255 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753109AbaFJVdf (ORCPT ); Tue, 10 Jun 2014 17:33:35 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="353256278" Date: Tue, 10 Jun 2014 17:33:33 -0400 From: Matthew Wilcox To: Keith Busch Cc: Jens Axboe , Matias =?iso-8859-1?Q?Bj=F8rling?= , "sbradshaw@micron.com" , "tom.leiming@gmail.com" , "hch@infradead.org" , "linux-kernel@vger.kernel.org" , "linux-nvme@lists.infradead.org" Subject: Re: [PATCH v7] NVMe: conversion to blk-mq Message-ID: <20140610213333.GA10055@linux.intel.com> References: <1402392038-5268-1-git-send-email-m@bjorling.me> <1402392038-5268-2-git-send-email-m@bjorling.me> <5397636F.9050209@fb.com> <5397753B.2020009@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 10, 2014 at 03:21:18PM -0600, Keith Busch wrote: > Yeah, nvme_setup_prps is probably the least readable code in this driver. > Maybe some comments are in order here... > > There are two rules for an SGL to be mappable to a PRP: > > 1. Every element must have zero page offset, except the first. > > 2. Every element must end on a page boundary, except the last. Or to put it another way, NVMe PRPs only support I/Os that describe a single range of virtual memory. -- 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/