path: root/Documentation/device-mapper/dm-crypt.txt
diff options
Diffstat (limited to 'Documentation/device-mapper/dm-crypt.txt')
1 files changed, 15 insertions, 3 deletions
diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index 2c656ae43ba7..571f24ffc91c 100644
--- 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:
Parameters: <cipher> <key> <iv_offset> <device path> \
<offset> [<#opt_params> <opt_params>]
Encryption cipher and an optional IV generation mode.
- (In format cipher[:keycount]-chainmode-ivopts:ivmode).
+ (In format cipher[:keycount]-chainmode-ivmode[:ivopts]).
@@ -19,7 +22,11 @@ Parameters: <cipher> <key> <iv_offset> <device path> \
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.
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
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.
+ 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