Merge branch 'linux-3.10.y' of git://git.kernel.org/pub/scm/linux/kernel/git/stable...

[firefly-linux-kernel-4.4.55.git] / Documentation / device-mapper / dm-crypt.txt

diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index 2c656ae43ba7f9907571c181ad4800ea5ceeaa9f..571f24ffc91c42a8a175688fa70dacce7c1643f9 100644 (file)
--- a/Documentation/device-mapper/dm-crypt.txt
+++ b/Documentation/device-mapper/dm-crypt.txt
@@ -4,12 +4,15 @@ dm-crypt
 Device-Mapper's "crypt" target provides transparent encryption of block devices
 using the kernel crypto API.
 
+For a more detailed description of supported parameters see:
+http://code.google.com/p/cryptsetup/wiki/DMCrypt
+
 Parameters: <cipher> <key> <iv_offset> <device path> \
              <offset> [<#opt_params> <opt_params>]
 
 <cipher>
     Encryption cipher and an optional IV generation mode.
-    (In format cipher[:keycount]-chainmode-ivopts:ivmode).
+    (In format cipher[:keycount]-chainmode-ivmode[:ivopts]).
     Examples:
        des
        aes-cbc-essiv:sha256
@@ -19,7 +22,11 @@ Parameters: <cipher> <key> <iv_offset> <device path> \
 
 <key>
     Key used for encryption. It is encoded as a hexadecimal number.
-    You can only use key sizes that are valid for the selected cipher.
+    You can only use key sizes that are valid for the selected cipher
+    in combination with the selected iv mode.
+    Note that for some iv modes the key string can contain additional
+    keys (for example IV seed) so the key contains more parts concatenated
+    into a single string.
 
 <keycount>
     Multi-key compatibility mode. You can define <keycount> keys and
@@ -44,7 +51,7 @@ Parameters: <cipher> <key> <iv_offset> <device path> \
     Otherwise #opt_params is the number of following arguments.
 
     Example of optional parameters section:
-        1 allow_discards
+        2 allow_discards same_cpu_crypt
 
 allow_discards
     Block discard requests (a.k.a. TRIM) are passed through the crypt device.
@@ -56,6 +63,11 @@ allow_discards
     used space etc.) if the discarded blocks can be located easily on the
     device later.
 
+same_cpu_crypt
+    Perform encryption using the same cpu that IO was submitted on.
+    The default is to use an unbound workqueue so that encryption work
+    is automatically balanced between available CPUs.
+
 Example scripts
 ===============
 LUKS (Linux Unified Key Setup) is now the preferred way to set up disk