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-@c
-@c COPYRIGHT (c) 1989-2011.
-@c On-Line Applications Research Corporation (OAR).
-@c All rights reserved.
-
-@node Glossary, Command and Variable Index, Example Application, Top
-@chapter Glossary
-
-@table @dfn
-@item active
-A term used to describe an object
-which has been created by an application.
-
-@item aperiodic task
-A task which must execute only at
-irregular intervals and has only a soft deadline.
-
-@item application
-In this document, software which makes
-use of RTEMS.
-
-@item ASR
-see Asynchronous Signal Routine.
-
-@item asynchronous
-Not related in order or timing to
-other occurrences in the system.
-
-@item Asynchronous Signal Routine
-Similar to a hardware
-interrupt except that it is associated with a task and is run in
-the context of a task. The directives provided by the signal
-manager are used to service signals.
-
-@item atomic operations
-Atomic operations are defined in terms of @cite{ISO/IEC 9899:2011}.
-
-@item awakened
-A term used to describe a task that has
-been unblocked and may be scheduled to the CPU.
-
-@item big endian
-A data representation scheme in which
-the bytes composing a numeric value are arranged such that the
-most significant byte is at the lowest address.
-
-@item bit-mapped
-A data encoding scheme in which each bit
-in a variable is used to represent something different. This
-makes for compact data representation.
-
-@item block
-A physically contiguous area of memory.
-
-@item blocked task
-The task state entered by a task which has been previously started and cannot
-continue execution until the reason for waiting has been satisfied. Blocked
-tasks are not an element of the set of ready tasks of a scheduler instance.
-
-@item broadcast
-To simultaneously send a message to a
-logical set of destinations.
-
-@item BSP
-see Board Support Package.
-
-@item Board Support Package
-A collection of device
-initialization and control routines specific to a particular
-type of board or collection of boards.
-
-@item buffer
-A fixed length block of memory allocated
-from a partition.
-
-@item calling convention
-The processor and compiler
-dependent rules which define the mechanism used to invoke
-subroutines in a high-level language. These rules define the
-passing of arguments, the call and return mechanism, and the
-register set which must be preserved.
-
-@item Central Processing Unit
-This term is equivalent to
-the terms processor and microprocessor.
-
-@item chain
-A data structure which allows for efficient
-dynamic addition and removal of elements. It differs from an
-array in that it is not limited to a predefined size.
-
-@item cluster
-We have clustered scheduling in case the set of processors of a system is
-partitioned into non-empty pairwise disjoint subsets. These subsets are called
-@dfn{clusters}. Clusters with a cardinality of one are partitions. Each
-cluster is owned by exactly one scheduler instance.
-
-@item coalesce
-The process of merging adjacent holes into
-a single larger hole. Sometimes this process is referred to as
-garbage collection.
-
-@item Configuration Table
-A table which contains
-information used to tailor RTEMS for a particular application.
-
-@item context
-All of the processor registers and
-operating system data structures associated with a task.
-
-@item context switch
-Alternate term for task switch.
-Taking control of the processor from one task and transferring
-it to another task.
-
-@item control block
-A data structure used by the
-executive to define and control an object.
-
-@item core
-When used in this manual, this term refers to
-the internal executive utility functions. In the interest of
-application portability, the core of the executive should not be
-used directly by applications.
-
-@item CPU
-An acronym for Central Processing Unit.
-
-@item critical section
-A section of code which must be
-executed indivisibly.
-
-@item CRT
-An acronym for Cathode Ray Tube. Normally used
-in reference to the man-machine interface.
-
-@item deadline
-A fixed time limit by which a task must
-have completed a set of actions. Beyond this point, the results
-are of reduced value and may even be considered useless or
-harmful.
-
-@item device
-A peripheral used by the application that
-requires special operation software. See also device driver.
-
-@item device driver
-Control software for special
-peripheral devices used by the application.
-
-@item directives
-RTEMS' provided routines that provide
-support mechanisms for real-time applications.
-
-@item dispatch
-The act of loading a task's context onto
-the CPU and transferring control of the CPU to that task.
-
-@item dormant
-The state entered by a task after it is
-created and before it has been started.
-
-@item Device Driver Table
-A table which contains the
-entry points for each of the configured device drivers.
-
-@item dual-ported
-A term used to describe memory which
-can be accessed at two different addresses.
-
-@item embedded
-An application that is delivered as a
-hidden part of a larger system. For example, the software in a
-fuel-injection control system is an embedded application found
-in many late-model automobiles.
-
-@item envelope
-A buffer provided by the MPCI layer to
-RTEMS which is used to pass messages between nodes in a
-multiprocessor system. It typically contains routing
-information needed by the MPCI. The contents of an envelope are
-referred to as a packet.
-
-@item entry point
-The address at which a function or task
-begins to execute. In C, the entry point of a function is the
-function's name.
-
-@item events
-A method for task communication and
-synchronization. The directives provided by the event manager
-are used to service events.
-
-@item exception
-A synonym for interrupt.
-
-@item executing task
-The task state entered by a task after it has been given control of the
-processor. On SMP configurations a task may be registered as executing on more
-than one processor for short time frames during task migration. Blocked tasks
-can be executing until they issue a thread dispatch.
-
-@item executive
-In this document, this term is used to
-referred to RTEMS. Commonly, an executive is a small real-time
-operating system used in embedded systems.
-
-@item exported
-An object known by all nodes in a
-multiprocessor system. An object created with the GLOBAL
-attribute will be exported.
-
-@item external address
-The address used to access
-dual-ported memory by all the nodes in a system which do not own
-the memory.
-
-@item FIFO
-An acronym for First In First Out.
-
-@item First In First Out
-A discipline for manipulating entries in a data structure.
-
-@item floating point coprocessor
-A component used in
-computer systems to enhance performance in mathematically
-intensive situations. It is typically viewed as a logical
-extension of the primary processor.
-
-@item freed
-A resource that has been released by the
-application to RTEMS.
-
-@item Giant lock
-The @dfn{Giant lock} is a recursive SMP lock protecting most parts of the
-operating system state. Virtually every operating system service must acquire
-and release the Giant lock during its operation.
-
-@item global
-An object that has been created with the
-GLOBAL attribute and exported to all nodes in a multiprocessor
-system.
-
-@item handler
-The equivalent of a manager, except that it
-is internal to RTEMS and forms part of the core. A handler is a
-collection of routines which provide a related set of functions.
-For example, there is a handler used by RTEMS to manage all
-objects.
-
-@item hard real-time system
-A real-time system in which a
-missed deadline causes the worked performed to have no value or
-to result in a catastrophic effect on the integrity of the
-system.
-
-@item heap
-A data structure used to dynamically allocate
-and deallocate variable sized blocks of memory.
-
-@item heir task
-A task is an @dfn{heir} if it is registered as an heir in a processor of the
-system. A task can be the heir on at most one processor in the system. In
-case the executing and heir tasks differ on a processor and a thread dispatch
-is marked as necessary, then the next thread dispatch will make the heir task
-the executing task.
-
-@item heterogeneous
-A multiprocessor computer system composed of dissimilar processors.
-
-@item homogeneous
-A multiprocessor computer system composed of a single type of processor.
-
-@item ID
-An RTEMS assigned identification tag used to
-access an active object.
-
-@item IDLE task
-A special low priority task which assumes
-control of the CPU when no other task is able to execute.
-
-@item interface
-A specification of the methodology used
-to connect multiple independent subsystems.
-
-@item internal address
-The address used to access
-dual-ported memory by the node which owns the memory.
-
-@item interrupt
-A hardware facility that causes the CPU
-to suspend execution, save its status, and transfer control to a
-specific location.
-
-@item interrupt level
-A mask used to by the CPU to
-determine which pending interrupts should be serviced. If a
-pending interrupt is below the current interrupt level, then the
-CPU does not recognize that interrupt.
-
-@item Interrupt Service Routine
-An ISR is invoked by the
-CPU to process a pending interrupt.
-
-@item I/O
-An acronym for Input/Output.
-
-@item ISR
-An acronym for Interrupt Service Routine.
-
-@item kernel
-In this document, this term is used as a
-synonym for executive.
-
-@item list
-A data structure which allows for dynamic
-addition and removal of entries. It is not statically limited
-to a particular size.
-
-@item little endian
-A data representation scheme in which
-the bytes composing a numeric value are arranged such that the
-least significant byte is at the lowest address.
-
-@item local
-An object which was created with the LOCAL
-attribute and is accessible only on the node it was created and
-resides upon. In a single processor configuration, all objects
-are local.
-
-@item local operation
-The manipulation of an object which
-resides on the same node as the calling task.
-
-@item logical address
-An address used by an application.
-In a system without memory management, logical addresses will
-equal physical addresses.
-
-@item loosely-coupled
-A multiprocessor configuration
-where shared memory is not used for communication.
-
-@item major number
-The index of a device driver in the
-Device Driver Table.
-
-@item manager
-A group of related RTEMS' directives which
-provide access and control over resources.
-
-@item memory pool
-Used interchangeably with heap.
-
-@item message
-A sixteen byte entity used to communicate
-between tasks. Messages are sent to message queues and stored
-in message buffers.
-
-@item message buffer
-A block of memory used to store
-messages.
-
-@item message queue
-An RTEMS object used to synchronize
-and communicate between tasks by transporting messages between
-sending and receiving tasks.
-
-@item Message Queue Control Block
-A data structure associated with each message queue used by RTEMS
-to manage that message queue.
-
-@item minor number
-A numeric value passed to a device
-driver, the exact usage of which is driver dependent.
-
-@item mode
-An entry in a task's control block that is
-used to determine if the task allows preemption, timeslicing,
-processing of signals, and the interrupt disable level used by
-the task.
-
-@item MPCI
-An acronym for Multiprocessor Communications
-Interface Layer.
-
-@item multiprocessing
-The simultaneous execution of two
-or more processes by a multiple processor computer system.
-
-@item multiprocessor
-A computer with multiple CPUs
-available for executing applications.
-
-@item Multiprocessor Communications Interface Layer
-A set
-of user-provided routines which enable the nodes in a
-multiprocessor system to communicate with one another.
-
-@item Multiprocessor Configuration Table
-The data structure defining the characteristics of the multiprocessor
-target system with which RTEMS will communicate.
-
-@item multitasking
-The alternation of execution amongst a
-group of processes on a single CPU. A scheduling algorithm is
-used to determine which process executes at which time.
-
-@item mutual exclusion
-A term used to describe the act of
-preventing other tasks from accessing a resource simultaneously.
-
-@item nested
-A term used to describe an ASR that occurs
-during another ASR or an ISR that occurs during another ISR.
-
-@item node
-A term used to reference a processor running
-RTEMS in a multiprocessor system.
-
-@item non-existent
-The state occupied by an uncreated or
-deleted task.
-
-@item numeric coprocessor
-A component used in computer
-systems to enhance performance in mathematically intensive
-situations. It is typically viewed as a logical extension of
-the primary processor.
-
-@item object
-In this document, this term is used to refer
-collectively to tasks, timers, message queues, partitions,
-regions, semaphores, ports, and rate monotonic periods. All
-RTEMS objects have IDs and user-assigned names.
-
-@item object-oriented
-A term used to describe systems
-with common mechanisms for utilizing a variety of entities.
-Object-oriented systems shield the application from
-implementation details.
-
-@item operating system
-The software which controls all
-the computer's resources and provides the base upon which
-application programs can be written.
-
-@item overhead
-The portion of the CPUs processing power
-consumed by the operating system.
-
-@item packet
-A buffer which contains the messages passed
-between nodes in a multiprocessor system. A packet is the
-contents of an envelope.
-
-@item partition
-An RTEMS object which is used to allocate
-and deallocate fixed size blocks of memory from an dynamically
-specified area of memory.
-
-@item partition
-Clusters with a cardinality of one are @dfn{partitions}.
-
-@item Partition Control Block
-A data structure associated
-with each partition used by RTEMS to manage that partition.
-
-@item pending
-A term used to describe a task blocked
-waiting for an event, message, semaphore, or signal.
-
-@item periodic task
-A task which must execute at regular
-intervals and comply with a hard deadline.
-
-@item physical address
-The actual hardware address of a
-resource.
-
-@item poll
-A mechanism used to determine if an event has
-occurred by periodically checking for a particular status.
-Typical events include arrival of data, completion of an action,
-and errors.
-
-@item pool
-A collection from which resources are
-allocated.
-
-@item portability
-A term used to describe the ease with
-which software can be rehosted on another computer.
-
-@item posting
-The act of sending an event, message,
-semaphore, or signal to a task.
-
-@item preempt
-The act of forcing a task to relinquish the
-processor and dispatching to another task.
-
-@item priority
-A mechanism used to represent the relative
-importance of an element in a set of items. RTEMS uses priority
-to determine which task should execute.
-
-@item priority boosting
-A simple approach to extend the priority inheritance protocol for clustered
-scheduling is @dfn{priority boosting}. In case a mutex is owned by a task of
-another cluster, then the priority of the owner task is raised to an
-artificially high priority, the pseudo-interrupt priority.
-
-@item priority inheritance
-An algorithm that calls for
-the lower priority task holding a resource to have its priority
-increased to that of the highest priority task blocked waiting
-for that resource. This avoids the problem of priority
-inversion.
-
-@item priority inversion
-A form of indefinite
-postponement which occurs when a high priority tasks requests
-access to shared resource currently allocated to low priority
-task. The high priority task must block until the low priority
-task releases the resource.
-
-@item processor utilization
-The percentage of processor
-time used by a task or a set of tasks.
-
-@item proxy
-An RTEMS control structure used to represent,
-on a remote node, a task which must block as part of a remote
-operation.
-
-@item Proxy Control Block
-A data structure associated
-with each proxy used by RTEMS to manage that proxy.
-
-@item PTCB
-An acronym for Partition Control Block.
-
-@item PXCB
-An acronym for Proxy Control Block.
-
-@item quantum
-The application defined unit of time in
-which the processor is allocated.
-
-@item queue
-Alternate term for message queue.
-
-@item QCB
-An acronym for Message Queue Control Block.
-
-@item ready task
-A task occupies this state when it is available to be given control of a
-processor. A ready task has no processor assigned. The scheduler decided that
-other tasks are currently more important. A task that is ready to execute and
-has a processor assigned is called scheduled.
-
-@item real-time
-A term used to describe systems which are
-characterized by requiring deterministic response times to
-external stimuli. The external stimuli require that the
-response occur at a precise time or the response is incorrect.
-
-@item reentrant
-A term used to describe routines which do
-not modify themselves or global variables.
-
-@item region
-An RTEMS object which is used to allocate
-and deallocate variable size blocks of memory from a dynamically
-specified area of memory.
-
-@item Region Control Block
-A data structure associated
-with each region used by RTEMS to manage that region.
-
-@item registers
-Registers are locations physically
-located within a component, typically used for device control or
-general purpose storage.
-
-@item remote
-Any object that does not reside on the local
-node.
-
-@item remote operation
-The manipulation of an object
-which does not reside on the same node as the calling task.
-
-@item return code
-Also known as error code or return
-value.
-
-@item resource
-A hardware or software entity to which
-access must be controlled.
-
-@item resume
-Removing a task from the suspend state. If
-the task's state is ready following a call to the
-@code{@value{DIRPREFIX}task_resume}
-directive, then the task is available for scheduling.
-
-@item return code
-A value returned by RTEMS directives to
-indicate the completion status of the directive.
-
-@item RNCB
-An acronym for Region Control Block.
-
-@item round-robin
-A task scheduling discipline in which
-tasks of equal priority are executed in the order in which they
-are made ready.
-
-@item RS-232
-A standard for serial communications.
-
-@item running
-The state of a rate monotonic timer while
-it is being used to delineate a period. The timer exits this
-state by either expiring or being canceled.
-
-@item schedulable
-A set of tasks which can be guaranteed
-to meet their deadlines based upon a specific scheduling
-algorithm.
-
-@item schedule
-The process of choosing which task should
-next enter the executing state.
-
-@item scheduled task
-A task is @dfn{scheduled} if it is allowed to execute and has a processor
-assigned. Such a task executes currently on a processor or is about to start
-execution. A task about to start execution it is an heir task on exactly one
-processor in the system.
-
-@item scheduler
-A @dfn{scheduler} or @dfn{scheduling algorithm} allocates processors to a
-subset of its set of ready tasks. So it manages access to the processor
-resource. Various algorithms exist to choose the tasks allowed to use a
-processor out of the set of ready tasks. One method is to assign each task a
-priority number and assign the tasks with the lowest priority number to one
-processor of the set of processors owned by a scheduler instance.
-
-@item scheduler instance
-A @dfn{scheduler instance} is a scheduling algorithm with a corresponding
-context to store its internal state. Each processor in the system is owned by
-at most one scheduler instance. The processor to scheduler instance assignment
-is determined at application configuration time. @xref{Configuring a System
-Configuring Clustered Schedulers}.
-
-@item segments
-Variable sized memory blocks allocated
-from a region.
-
-@item semaphore
-An RTEMS object which is used to
-synchronize tasks and provide mutually exclusive access to
-resources.
-
-@item Semaphore Control Block
-A data structure associated
-with each semaphore used by RTEMS to manage that semaphore.
-
-@item shared memory
-Memory which is accessible by
-multiple nodes in a multiprocessor system.
-
-@item signal
-An RTEMS provided mechanism to communicate
-asynchronously with a task. Upon reception of a signal, the ASR
-of the receiving task will be invoked.
-
-@item signal set
-A thirty-two bit entity which is used to
-represent a task's collection of pending signals and the signals
-sent to a task.
-
-@item SMCB
-An acronym for Semaphore Control Block.
-
-@item SMP locks
-The @dfn{SMP locks} ensure mutual exclusion on the lowest level and are a
-replacement for the sections of disabled interrupts. Interrupts are usually
-disabled while holding an SMP lock. They are implemented using atomic
-operations. Currently a ticket lock is used in RTEMS.
-
-@item SMP barriers
-The @dfn{SMP barriers} ensure that a defined set of independent threads of
-execution on a set of processors reaches a common synchronization point in
-time. They are implemented using atomic operations. Currently a sense barrier
-is used in RTEMS.
-
-@item soft real-time system
-A real-time system in which a
-missed deadline does not compromise the integrity of the system.
-
-@item sporadic task
-A task which executes at irregular
-intervals and must comply with a hard deadline. A minimum
-period of time between successive iterations of the task can be
-guaranteed.
-
-@item stack
-A data structure that is managed using a Last
-In First Out (LIFO) discipline. Each task has a stack
-associated with it which is used to store return information
-and local variables.
-
-@item status code
-Also known as error code or return
-value.
-
-@item suspend
-A term used to describe a task that is not
-competing for the CPU because it has had a
-@code{@value{DIRPREFIX}task_suspend} directive.
-
-@item synchronous
-Related in order or timing to other
-occurrences in the system.
-
-@item system call
-In this document, this is used as an
-alternate term for directive.
-
-@item target
-The system on which the application will
-ultimately execute.
-
-@item task
-A logically complete thread of execution. It consists normally of a set of
-registers and a stack. The terms @dfn{task} and @dfn{thread} are synonym in
-RTEMS. The scheduler assigns processors to a subset of the ready tasks.
-
-@item Task Control Block
-A data structure associated with
-each task used by RTEMS to manage that task.
-
-@item task migration
-@dfn{Task migration} happens in case a task stops execution on one processor
-and resumes execution on another processor.
-
-@item task processor affinity
-The set of processors on which a task is allowed to execute.
-
-@item task switch
-Alternate terminology for context
-switch. Taking control of the processor from one task and given
-to another.
-
-@item TCB
-An acronym for Task Control Block.
-
-@item thread dispatch
-The @dfn{thread dispatch} transfers control of the processor from the currently
-executing thread to the heir thread of the processor.
-
-@item tick
-The basic unit of time used by RTEMS. It is a
-user-configurable number of microseconds. The current tick
-expires when the @code{@value{DIRPREFIX}clock_tick}
-directive is invoked.
-
-@item tightly-coupled
-A multiprocessor configuration
-system which communicates via shared memory.
-
-@item timeout
-An argument provided to a number of
-directives which determines the maximum length of time an
-application task is willing to wait to acquire the resource if
-it is not immediately available.
-
-@item timer
-An RTEMS object used to invoke subprograms at
-a later time.
-
-@item Timer Control Block
-A data structure associated
-with each timer used by RTEMS to manage that timer.
-
-@item timeslicing
-A task scheduling discipline in which
-tasks of equal priority are executed for a specific period of
-time before being preempted by another task.
-
-@item timeslice
-The application defined unit of time in
-which the processor is allocated.
-
-@item TMCB
-An acronym for Timer Control Block.
-
-@item transient overload
-A temporary rise in system
-activity which may cause deadlines to be missed. Rate Monotonic
-Scheduling can be used to determine if all deadlines will be met
-under transient overload.
-
-@item user extensions
-Software routines provided by the
-application to enhance the functionality of RTEMS.
-
-@item User Extension Table
-A table which contains the
-entry points for each user extensions.
-
-@item User Initialization Tasks Table
-A table which
-contains the information needed to create and start each of the
-user initialization tasks.
-
-@item user-provided
-Alternate term for user-supplied.
-This term is used to designate any software routines which must
-be written by the application designer.
-
-@item user-supplied
-Alternate term for user-provided.
-This term is used to designate any software routines which must
-be written by the application designer.
-
-@item vector
-Memory pointers used by the processor to
-fetch the address of routines which will handle various
-exceptions and interrupts.
-
-@item wait queue
-The list of tasks blocked pending the
-release of a particular resource. Message queues, regions, and
-semaphores have a wait queue associated with them.
-
-@item yield
-When a task voluntarily releases control of the processor.
-
-@end table
-