From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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) From: Vishal Verma 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> MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: linux-nvdimm@lists.01.org List-ID: 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 --- 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: -- 2.20.1 _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm