summaryrefslogtreecommitdiffstats
path: root/drivers/nvdimm/pfn.h
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/nvdimm/pfn.h')
-rw-r--r--drivers/nvdimm/pfn.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h
index acb19517f678..37cb1b8a2a39 100644
--- a/drivers/nvdimm/pfn.h
+++ b/drivers/nvdimm/pfn.h
@@ -24,6 +24,18 @@ struct nd_pfn_sb {
__le64 npfns;
__le32 mode;
/* minor-version-1 additions for section alignment */
+ /**
+ * @start_pad: Deprecated attribute to pad start-misaligned namespaces
+ *
+ * start_pad is deprecated because the original definition did
+ * not comprehend that dataoff is relative to the base address
+ * of the namespace not the start_pad adjusted base. The result
+ * is that the dax path is broken, but the block-I/O path is
+ * not. The kernel will no longer create namespaces using start
+ * padding, but it still supports block-I/O for legacy
+ * configurations mainly to allow a backup, reconfigure the
+ * namespace, and restore flow to repair dax operation.
+ */
__le32 start_pad;
__le32 end_trunc;
/* minor-version-2 record the base alignment of the mapping */