Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031047AbbD1WVq (ORCPT ); Tue, 28 Apr 2015 18:21:46 -0400 Received: from mail-ie0-f172.google.com ([209.85.223.172]:36602 "EHLO mail-ie0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030901AbbD1WVp (ORCPT ); Tue, 28 Apr 2015 18:21:45 -0400 MIME-Version: 1.0 In-Reply-To: References: <20150428181203.35812.60474.stgit@dwillia2-desk3.amr.corp.intel.com> <20150428182514.35812.12126.stgit@dwillia2-desk3.amr.corp.intel.com> Date: Tue, 28 Apr 2015 15:21:44 -0700 Message-ID: Subject: Re: [Linux-nvdimm] [PATCH v2 11/20] libnd, nd_pmem: add libnd support to the pmem driver From: Phil Pokorny To: Andy Lutomirski Cc: Dan Williams , linux-nvdimm , "linux-kernel@vger.kernel.org" , Christoph Hellwig , Jens Axboe , "H. Peter Anvin" , Ingo Molnar Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1656 Lines: 45 On Tue, Apr 28, 2015 at 2:04 PM, Andy Lutomirski wrote: > On Tue, Apr 28, 2015 at 11:25 AM, Dan Williams wrote: >> +config ND_E820 >> + tristate "E820: Support the E820-type-12 PMEM convention" >> + depends on X86_PMEM_LEGACY >> + default m if X86_PMEM_LEGACY >> + select LIBND >> + help >> + Prior to ACPI 6 some platforms advertised peristent memory >> + via type-12 e820 memory ranges. Create a libnd bus and >> + attach an instance of the pmem driver to these ranges. >> + > > How about something like: > > "This driver allows libnd to work with legacy, pre-ACPI 6 NVDIMMs. > This enables such devices to be exposed as block devices using PMEM. > > The legacy NVDIMM interface is problematic. This driver will not work > if you boot using UEFI, and some NVDIMMs and motherboards that work > with this driver may require proprietary code in order to work > reliably." Perhaps not "problematic" but "requires a BIOS in Legacy mode" It might also mention that if you use the kernel command line memmap=nn!ss syntax it adds a type 12 region to the e820 map and so you would want this support. If you have a motherboard with UEFI support for NVDIMM's that would be the recommended configuration. Phil P. -- Philip Pokorny, RHCE Chief Technology Officer PENGUIN COMPUTING, Inc www.penguincomputing.com -- 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/