First page Back Continue Last page Graphics
dm-ioctl
During initialisation, Device Mapper sets up a misc control device for ioctl communication.
This has major number 10 (misc) and a dynamically-allocated minor number (normally 63).
Distributions set up /dev/mapper/control with the correct device number read from /proc/devices (misc) and /proc/misc (device-mapper).
Some distributions use the supplied devmap_mknod shell script. Fedora uses a 'mkdmnod' command built into the initrd's shell (nash). If Device Mapper is built as a module you can add a post-install line to modules.conf to run the script.
As of tools version 1.00.21 (7th Jan 2005) /dev/mapper/control is checked transparently by libdevmapper and if necessary tries to fix it, so it's no longer necessary for distributions to deal with this provided /dev can be written to.