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man pages section 4: Device and Network Interfaces

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Updated: Thursday, June 13, 2019
 
 

lofi(4D)

Name

lofi - Loopback file driver

Description

The lofi file driver exports a file as a block device, enabling system utilities such as fstyp(8), fsck(8) and mount(8) to operate on underlying file system images (including CD-ROM images) contained on the block device. Reads and writes to the block device are translated to reads and writes on the exported file. See lofiadm(8) for examples.

Either a labeled or an unlabeled device can be created while exporting a file as a block device. As compared to an unlabeled device, it is easier to access partitions and slices on the disk image file with labeled device.

For an unlabeled device, block device entries are contained in /dev/lofi The /dev/rlofi file contains the character (or raw) device assigned through lofiadm(8).

For a labeled device, block device entries are contained in /dev/dsk while raw device entries are under /dev/rdsk. As with normal disks, entries are named in cXtYd0 form by lofiadm(8).

When created, these device entries are owned by root, in group sys, and have permissions of 0600. Ownership, group, and permission settings can be altered, however there may be ramifications. See lofiadm(8) for more information.

lofi devices can be compressed. See lofiadm(8) for more information.

Files exported through lofi can also be encrypted. See lofiadm(8) for details on how to specify encryption keys.

Normally, one file can be exported as only one block device. However, a removable block device can be created so that one file can be exported through multiple block devices at the same time in a read-only way. Also, one removable device can be used to export different file at different time. See lofiadm(8) for details on how to create removable devices.

Files

/dev/lofictl

Master control device.

/dev/lofi/n

Block device of an unlabeled lofi device.

/dev/rlofi/n

Character device of an unlabeled lofi device.

/dev/dsk/cXtYd0*

Block device of a labeled lofi device.

/dev/rdsk/cXtYd0*

Character device of a labeled lofi device.

/kernel/drv/sparcv9/lofi

64-bit driver (SPARC).

/kernel/drv/amd64/lofi

64-bit driver (x86).

/kernel/drv/lofi.conf

Driver configuration file. (Do not alter).

Attributes

See attributes(7) for a description of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Architecture
SPARC, x86
Availability
system/core-os, system/kernel
Interface Stability
Committed

See Also

lofs(4FS), attributes(7), fsck(8), fstyp(8), lofiadm(8), mount(8), newfs(8)

Notes

Just as you would not directly access a disk device that has mounted file systems, you should not access a file associated with a block device except through the lofi file driver.

For compatibility purposes, a raw device is also exported with the block device. (For example, newfs(8)).