From patchwork Thu Aug 8 17:57:07 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Verma, Vishal L" X-Patchwork-Id: 11084613 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B7F1014DB for ; Thu, 8 Aug 2019 17:57:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AABDD28B8D for ; Thu, 8 Aug 2019 17:57:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9EC6928B93; Thu, 8 Aug 2019 17:57:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 57DF628B8D for ; Thu, 8 Aug 2019 17:57:11 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 3D8EC2130A502; Thu, 8 Aug 2019 10:59:41 -0700 (PDT) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=192.55.52.43; helo=mga05.intel.com; envelope-from=vishal.l.verma@intel.com; receiver=linux-nvdimm@lists.01.org Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id D181121309DC0 for ; Thu, 8 Aug 2019 10:59:40 -0700 (PDT) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Aug 2019 10:57:10 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,362,1559545200"; d="scan'208";a="203661289" Received: from vverma7-desk1.lm.intel.com ([10.232.112.185]) by fmsmga002.fm.intel.com with ESMTP; 08 Aug 2019 10:57:10 -0700 From: Vishal Verma To: Subject: [ndctl PATCH v2] Documentation/namespace-description: Clarify label-less restrictions Date: Thu, 8 Aug 2019 11:57:07 -0600 Message-Id: <20190808175707.9089-1-vishal.l.verma@intel.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Virus-Scanned: ClamAV using ClamSMTP In the ndctl-create-namespace (and related) man pages, add a clarification note regarding some of the restrictions a user may see when operating on label-less namespaces. Link: https://github.com/pmem/ndctl/issues/52 Reported-by: Jane Chu Cc: Dan Williams Signed-off-by: Vishal Verma Reviewed-by: Jeff Moyer --- v2: - Remove the part about an address abstraction mechanism; It didn't add any value (Jeff) - Add an additional sentence about space reclamation semantics (Dan) Documentation/ndctl/namespace-description.txt | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/ndctl/namespace-description.txt b/Documentation/ndctl/namespace-description.txt index 94999e5..c59fbef 100644 --- a/Documentation/ndctl/namespace-description.txt +++ b/Documentation/ndctl/namespace-description.txt @@ -18,6 +18,15 @@ the kernel's 'memmap=ss!nn' command line option (see the nvdimm wiki on kernel.org), or NVDIMMs without a valid 'namespace index' in their label area. +NOTE: Label-less namespaces lack many of the features of their label-rich +cousins. For example, their size cannot be modified, or they cannot be +fully 'destroyed' (i.e. the space reclaimed). A destroy operation will +zero any mode-specific metadata. Finally, for create-namespace operations +on label-less namespaces, ndctl bypasses the region capacity availability +checks, and always satisfies the request using the full region capacity. +The only reconfiguration operation supported on a label-less namespace +is changing its 'mode'. + A namespace can be provisioned to operate in one of 4 modes, 'fsdax', 'devdax', 'sector', and 'raw'. Here are the expected usage models for these modes: