Arch Linux

Description:
/usr/lib/initcpio/hooks/encrypt supports :allow-discards, but this support is undocumented by mkinitcpio -H encrypt.

Additional info:
* cryptsetup-2.2.1-1

output of mkinitcpio -H encrypt:
==> Help for hook 'encrypt':
This hook allows for an encrypted root device. Users should specify the device
to be unlocked using 'cryptdevice=device:dmname' on the kernel command line,
where 'device' is the path to the raw device, and 'dmname' is the name given to
the device after unlocking, and will be available as /dev/mapper/dmname.

For unlocking via keyfile, 'cryptkey=device:fstype:path' should be specified on
the kernel cmdline, where 'device' represents the raw block device where the key
exists, 'fstype' is the filesystem type of 'device' (or auto), and 'path' is
the absolute path of the keyfile within the device.

Without specifying a keyfile, you will be prompted for the password at runtime.
This means you must have a keyboard available to input it, and you may need
the keymap hook as well to ensure that the keyboard is using the layout you
expect.

==> This hook has runtime scripts:
-> pre-mount hook