L

latched interrupt

(a.k.a. “edge-triggered interrupt”)

An interrupt that occurs at the transition from deasserted to asserted on the IRQ line.

layered driver

One of a collection of drivers that respond to the same IRPs. See also class driver, filter driver, intermediate driver, and I/O stack location.

The term “layered driver” describes the highest-level and lowest-level drivers in a chain of layered drivers that process the same IRPs, along with all intermediate drivers in the chain.

LBN

Logical block number

A logical block number identifies a physical block on a disk, using a logical address rather than physical disk values (for cylinder, track, and sector). For a disk with N blocks (a.k.a. “sectors”), the corresponding LBNs are numbered 0 through (N – 1). See also MCB and VBN.

level-sensitive interrupt

An interrupt that occurs when the signal is asserted on the IRQ line.

LPC

Local procedure call

See also IPC and port object.

little-endian

Refers to a processor memory architecture in which the byte layout is as follows:

·Byte N is the least significant (and, in conventional layout diagrams, the “rightmost”) byte of:

·A word composed of bytes N and (N + 1).

·A double word composed of bytes N, (N + 1), (N + 2), and (N + 3).

·A K-byte memory entity composed of bytes N, (N + 1),...,(N + K – 1).

The address of the preceding word, double word, or K-byte entity is its least significant byte, N.

Intel microprocessors always support little-endian addressing. Some RISC microprocessors can be configured for either big-endian or little-endian addressing. For a little-endian configuration, the least significant bit of a 16-bit short value is the “rightmost” bit at byte N, while the most significant bit is the “leftmost” bit of byte (N + 1). See also big-endian.

logical memory

A HAL-provided mapping between system physical memory and a device-accessible address range. See also map.

LSA

Local Security Authority

An integral subsystem responsible for managing security access tokens for users.

LU

Logical unit

From a SCSI-II HBA driver’s point of view, a physical or virtual peripheral device, addressable through a TID, attached to a SCSI bus. See also TID.

LUID

Locally unique identifier

See SID.