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c-user: Clarify interrupt manager directives
Use RTEMS coding style in all code blocks.
This commit is contained in:
Sebastian Huber
parent
674b71470b
commit
b2c766bc72
@ -23,13 +23,13 @@ from an ISR. The interrupt manager includes the following directive:
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- rtems_interrupt_disable_ - Disable Interrupts
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- rtems_interrupt_enable_ - Enable Interrupts
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- rtems_interrupt_enable_ - Restore Interrupt Level
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- rtems_interrupt_flash_ - Flash Interrupt
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- rtems_interrupt_local_disable_ - Disable Interrupts on Current Processor
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- rtems_interrupt_local_enable_ - Enable Interrupts on Current Processor
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- rtems_interrupt_local_enable_ - Restore Interrupt Level on Current Processor
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- rtems_interrupt_lock_initialize_ - Initialize an ISR Lock
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@ -330,32 +330,66 @@ DIRECTIVE STATUS CODES:
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DESCRIPTION:
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This directive disables all maskable interrupts and returns the previous
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``level``. A later invocation of the ``rtems_interrupt_enable`` directive
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should be used to restore the interrupt level.
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.. sidebar:: *Macro*
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This directive is implemented as a macro which modifies the ``level``
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parameter.
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interrupt level in ``level``.
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NOTES:
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A later invocation of the ``rtems_interrupt_enable`` directive should be
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used to restore the interrupt level.
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This directive is implemented as a macro which sets the ``level``
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parameter.
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This directive will not cause the calling task to be preempted.
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This directive is only available on uni-processor configurations. The
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directive ``rtems_interrupt_local_disable`` is available on all
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This directive is only available in uni-processor configurations. The
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directive ``rtems_interrupt_local_disable`` is available in all
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configurations.
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.. code-block:: c
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void critical_section( void )
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{
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rtems_interrupt level;
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/*
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* Please note that the rtems_interrupt_disable() is a macro. The
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* previous interrupt level (before the maskable interrupts are
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* disabled) is returned here in the level macro parameter. This
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* would be wrong:
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*
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* rtems_interrupt_disable( &level );
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*/
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rtems_interrupt_disable( level );
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/* Critical section, maskable interrupts are disabled */
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{
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rtems_interrupt level2;
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rtems_interrupt_disable( level2 );
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/* Nested critical section */
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rtems_interrupt_enable( level2 );
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}
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/* Maskable interrupts are still disabled */
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rtems_interrupt_enable( level );
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}
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.. raw:: latex
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\clearpage
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.. index:: enable interrupts
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.. index:: restore interrupt level
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.. index:: rtems_interrupt_enable
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.. _rtems_interrupt_enable:
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INTERRUPT_ENABLE - Enable Interrupts
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------------------------------------
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INTERRUPT_ENABLE - Restore Interrupt Level
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------------------------------------------
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CALLING SEQUENCE:
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.. code-block:: c
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@ -368,17 +402,20 @@ DIRECTIVE STATUS CODES:
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NONE
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DESCRIPTION:
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This directive enables maskable interrupts to the ``level`` which was
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returned by a previous call to ``rtems_interrupt_disable``. Immediately
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prior to invoking this directive, maskable interrupts should be disabled by
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a call to ``rtems_interrupt_disable`` and will be enabled when this
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directive returns to the caller.
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This directive restores the interrupt level specified by ``level``.
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NOTES:
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The ``level`` parameter value must be obtained by a previous call to
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``rtems_interrupt_disable`` or ``rtems_interrupt_flash``. Using an
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otherwise obtained value is undefined behaviour.
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This directive is unsuitable to enable particular interrupt sources, for
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example in an interrupt controller.
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This directive will not cause the calling task to be preempted.
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This directive is only available on uni-processor configurations. The
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directive ``rtems_interrupt_local_enable`` is available on all
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This directive is only available in uni-processor configurations. The
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directive ``rtems_interrupt_local_enable`` is available in all
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configurations.
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.. raw:: latex
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@ -411,6 +448,10 @@ DESCRIPTION:
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this sequence.
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NOTES:
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The ``level`` parameter value must be obtained by a previous call to
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``rtems_interrupt_disable`` or ``rtems_interrupt_flash``. Using an
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otherwise obtained value is undefined behaviour.
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This directive will not cause the calling task to be preempted.
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This directive is only available in uni-processor configurations. The
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@ -445,31 +486,65 @@ DIRECTIVE STATUS CODES:
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DESCRIPTION:
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This directive disables all maskable interrupts and returns the previous
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``level``. A later invocation of the ``rtems_interrupt_local_enable``
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directive should be used to restore the interrupt level.
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.. sidebar:: *Macro*
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This directive is implemented as a macro which modifies the ``level``
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parameter.
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interrupt level in ``level``.
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NOTES:
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A later invocation of the ``rtems_interrupt_local_enable`` directive should
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be used to restore the interrupt level.
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This directive is implemented as a macro which sets the ``level``
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parameter.
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This directive will not cause the calling task to be preempted.
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In SMP configurations, this will not ensure system wide mutual exclusion.
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Use interrupt locks instead.
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.. code-block:: c
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void local_critical_section( void )
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{
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rtems_interrupt level;
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/*
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* Please note that the rtems_interrupt_local_disable() is a macro.
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* The previous interrupt level (before the maskable interrupts are
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* disabled) is returned here in the level macro parameter. This
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* would be wrong:
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*
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* rtems_interrupt_local_disable( &level );
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*/
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rtems_interrupt_local_disable( level );
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/* Local critical section, maskable interrupts are disabled */
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{
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rtems_interrupt level2;
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rtems_interrupt_local_disable( level2 );
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/* Nested local critical section */
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rtems_interrupt_local_enable( level2 );
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}
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/* Maskable interrupts are still disabled */
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rtems_interrupt_local_enable( level );
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}
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.. raw:: latex
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\clearpage
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.. index:: enable interrupts
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.. index:: restore interrupt level
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.. index:: rtems_interrupt_local_enable
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.. _rtems_interrupt_local_enable:
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INTERRUPT_LOCAL_ENABLE - Enable Interrupts on Current Processor
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---------------------------------------------------------------
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INTERRUPT_LOCAL_ENABLE - Restore Interrupt Level on Current Processor
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---------------------------------------------------------------------
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CALLING SEQUENCE:
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.. code-block:: c
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@ -482,13 +557,17 @@ DIRECTIVE STATUS CODES:
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NONE
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DESCRIPTION:
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This directive enables maskable interrupts to the ``level`` which was
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returned by a previous call to ``rtems_interrupt_local_disable``.
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Immediately prior to invoking this directive, maskable interrupts should be
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disabled by a call to ``rtems_interrupt_local_disable`` and will be enabled
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when this directive returns to the caller.
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This directive restores the interrupt level specified by ``level`` on the
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current processor.
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NOTES:
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The ``level`` parameter value must be obtained by a previous call to
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``rtems_interrupt_local_disable``. Using an otherwise obtained value is
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undefined behaviour.
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This directive is unsuitable to enable particular interrupt sources, for
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example in an interrupt controller.
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This directive will not cause the calling task to be preempted.
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.. raw:: latex
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@ -543,15 +622,15 @@ DIRECTIVE STATUS CODES:
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NONE
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DESCRIPTION:
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Interrupts will be disabled. In SMP configurations, this directive
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acquires an SMP lock.
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Maskable interrupts will be disabled. In SMP configurations, this
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directive acquires an SMP lock.
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NOTES:
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A separate lock context must be provided for each acquire/release pair, for
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example an automatic variable.
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An attempt to recursively acquire the lock may result in an infinite loop
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with interrupts disabled.
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with maskable interrupts disabled.
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This directive will not cause the calling thread to be preempted. This
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directive can be used in thread and interrupt context.
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@ -579,7 +658,7 @@ DIRECTIVE STATUS CODES:
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NONE
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DESCRIPTION:
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The interrupt status will be restored. In SMP configurations, this
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The interrupt level will be restored. In SMP configurations, this
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directive releases an SMP lock.
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NOTES:
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@ -612,7 +691,7 @@ DIRECTIVE STATUS CODES:
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NONE
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DESCRIPTION:
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The interrupt status will remain unchanged. In SMP configurations, this
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The interrupt level will remain unchanged. In SMP configurations, this
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directive acquires an SMP lock.
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NOTES:
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@ -651,7 +730,7 @@ DIRECTIVE STATUS CODES:
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NONE
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DESCRIPTION:
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The interrupt status will remain unchanged. In SMP configurations, this
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The interrupt level will remain unchanged. In SMP configurations, this
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directive releases an SMP lock.
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NOTES:
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