Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755302AbbDTMxm (ORCPT ); Mon, 20 Apr 2015 08:53:42 -0400 Received: from verein.lst.de ([213.95.11.211]:36442 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754759AbbDTMxl (ORCPT ); Mon, 20 Apr 2015 08:53:41 -0400 Date: Mon, 20 Apr 2015 14:53:38 +0200 From: Christoph Hellwig To: Dan Williams Cc: Ingo Molnar , "linux-nvdimm@lists.01.org" , Boaz Harrosh , Neil Brown , Greg KH , "linux-kernel@vger.kernel.org" , Andy Lutomirski , Jens Axboe , "H. Peter Anvin" , Christoph Hellwig , Linus Torvalds , Andrew Morton Subject: Re: [PATCH 02/21] ND NFIT-Defined/NVIDIMM Subsystem Message-ID: <20150420125338.GA5463@lst.de> References: <20150418013256.25237.96403.stgit@dwillia2-desk3.amr.corp.intel.com> <20150418013525.25237.45181.stgit@dwillia2-desk3.amr.corp.intel.com> <20150420070624.GB13876@gmail.com> 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 Content-Length: 1999 Lines: 43 [I haven't much time to look through the patches, so only high level hand wavey comments for now, sorry..] On Mon, Apr 20, 2015 at 01:14:42AM -0700, Dan Williams wrote: > > So why on earth is this whole concept and the naming itself > > ('drivers/block/nd/' stands for 'NFIT Defined', apparently) revolving > > around a specific 'firmware' mindset and revolving around specific, > > weirdly named, overly complicated looking firmware interfaces that > > come with their own new weird glossary?? > > There's only three core properties of NVDIMMs that this implementation > cares about. > > 1/ directly mapped interleaved persistent memory (PMEM) > 2/ indirect mmio aperture accessed (windowed) persistent memory (BLK) > 3/ the possibility that those 2 access modes may alias the same > on-media addresses > > Most of complexity of the implementation is dealing with aspect 3, but > that complexity can and is bypassed in places. > > > Firmware might be a discovery method - or not. A non-volatile device > > might be e820 enumerated, or PCI discovered - potentially with all > > discovery handled by the driver. > > PCI attached non-volatile memory is NVMe. ND is handling address > ranges that support direct cpu load store. But those can't be attached in all kinds of different ways. It's not like this is a new thing - they've been used in Storage OEM systems for a long time, both on Intel platforms and other CPUs. And the current pmem.c can also handle cases like a PCI card exposing a large mmio region that can be used as persistent memory. So a big vote from me into namving this the pmem subsystem and trying to have names not too tied to one specific firmware interface. Once I'll go through this in more detail I'll comment more. -- 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/