CONFIG_NUM_METAIRQ_PRIORITIES

Number of very-high priority ‘preemptor’ threads

Type: int

Help

This defines a set of priorities at the (numerically) lowest
end of the range which have "meta-irq" behavior.  Runnable
threads at these priorities will always be scheduled before
threads at lower priorities, EVEN IF those threads are
otherwise cooperative and/or have taken a scheduler lock.
Making such a thread runnable in any way thus has the effect
of "interrupting" the current task and running the meta-irq
thread synchronously, like an exception or system call.  The
intent is to use these priorities to implement "interrupt
bottom half" or "tasklet" behavior, allowing driver
subsystems to return from interrupt context but be guaranteed
that user code will not be executed (on the current CPU)
until the remaining work is finished.  As this breaks the
"promise" of non-preemptibility granted by the current API
for cooperative threads, this tool probably shouldn't be used
from application code.

Defaults

• 1

• 0

Kconfig definitions

At <nRF>/subsys/net/openthread/Kconfig.defconfig:17

Included via <Zephyr>/Kconfig:8 → <Zephyr>/Kconfig.zephyr:33 → <Zephyr>/modules/Kconfig:6 → <nRF>/doc/_build/kconfig/Kconfig.modules:2 → <nRF>/Kconfig.nrf:7

Menu path: (Top) → Modules → nrf (/home/runner/work/sdk-nrf/sdk-nrf/ncs/nrf)

config NUM_METAIRQ_PRIORITIES
    int
    default 1
    depends on NET_L2_OPENTHREAD

---

At <Zephyr>/kernel/Kconfig:91

Included via <Zephyr>/Kconfig:8 → <Zephyr>/Kconfig.zephyr:40

Menu path: (Top) → General Kernel Options

config NUM_METAIRQ_PRIORITIES
    int "Number of very-high priority 'preemptor' threads"
    default 0
    help
      This defines a set of priorities at the (numerically) lowest
      end of the range which have "meta-irq" behavior.  Runnable
      threads at these priorities will always be scheduled before
      threads at lower priorities, EVEN IF those threads are
      otherwise cooperative and/or have taken a scheduler lock.
      Making such a thread runnable in any way thus has the effect
      of "interrupting" the current task and running the meta-irq
      thread synchronously, like an exception or system call.  The
      intent is to use these priorities to implement "interrupt
      bottom half" or "tasklet" behavior, allowing driver
      subsystems to return from interrupt context but be guaranteed
      that user code will not be executed (on the current CPU)
      until the remaining work is finished.  As this breaks the
      "promise" of non-preemptibility granted by the current API
      for cooperative threads, this tool probably shouldn't be used
      from application code.

(The ‘depends on’ condition includes propagated dependencies from ifs and menus.)