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 <jane.chu(a)oracle.com&gt; Cc: Dan Williams <dan.j.williams(a)intel.com&gt; Signed-off-by: Vishal Verma <vishal.l.verma(a)intel.com&gt; --- 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