1 files changed, 4 insertions, 2 deletions
diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt
index baf41118660d..7af2851d667c 100644
@@ -18,8 +18,10 @@ Usage
If you have a block device which supports DAX, you can make a filesystem
-on it as usual. When mounting it, use the -o dax option manually
-or add 'dax' to the options in /etc/fstab.
+on it as usual. The DAX code currently only supports files with a block
+size equal to your kernel's PAGE_SIZE, so you may need to specify a block
+size when creating the filesystem. When mounting it, use the "-o dax"
+option on the command line or add 'dax' to the options in /etc/fstab.
Implementation Tips for Block Driver Writers