On 21.03.24 20:28, Gedare Bloom wrote:
Two basic questions:
Does the priority field type need to be Architecture- or BSP-defined
or is uint32_t always going to be fine.
In theory, the priority range depends on the interrupt controller
implementation. However, an uint32_t should be more than enough. The
maximum priority value defines also the maximum interrupt nesting depth.
So, even 256 interrupt priority levels would be quite a lot.
Does changing (increasing) the priority of a vector from within
interrupt context possibly cause a pending interrupt to post that was
previously at a lower priority than the currently masked priority
level? In that case, it would cause a preemption to occur. I'm
guessing this behavior could be architecture-specific.
This behaviour is entirely interrupt-controller specific. Changing the
priority while an interrupt is active is usually a bad idea since this
can confuse the hardware interrupt priority stack. I guess we have to
add some interrupt-controller specific information to the notes, for
example:
For the Armv7-M NVIC, there are 256 priority levels supported. The
granularity of the priority levels depends on the interrupt controller
configuration. Some lower bits of a priority value may be read-as-zero.
Interrupts with a priority value less than 128 are not disabled by the
RTEMS interrupt disable directive. Such interrupts shall not use
operating system services.
For the Arm GICv2, ...
For the Arm GICv3, ...
I added those questions to the ticket also.
Gedare
On Wed, Mar 20, 2024 at 2:59 AM Sebastian Huber
<sebastian.hu...@embedded-brains.de> wrote:
Hello,
I added a ticket for a proposal for an API to get and set interrupt
priorities for interrupt vectors:
https://devel.rtems.org/ticket/5002
I would like to implement this API at least for the BSPs using the
ARM/AArch64 GIC.
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email: sebastian.hu...@embedded-brains.de
phone: +49-89-18 94 741 - 16
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