Revert "ipipe: ipipe_request_irq(), ipipe_free_irq() are root-only services"

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Signed-off-by Jan Kiszka <[email protected]>

---

We run all critical code under an I-pipe spin lock, so this restriction seems artificial. Nevertheless, I briefly checked if some arch has specific needs but didn't find any trace in core-3.5.

Wolfgang, this already resolves the issue I mentioned regarding startup of RTnet NICs.

 kernel/ipipe/core.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

kernel/ipipe/core.c +0 -4

index 9898b92..23a2146 100644
@@ -846,8 +846,6 @@ int ipipe_request_irq(struct ipipe_domain *ipd,
 	unsigned long flags;
 	int ret = 0;
 
-	ipipe_root_only();
-
 	if (handler == NULL ||
 	    (irq >= IPIPE_NR_XIRQS && !ipipe_virtual_irq_p(irq)))
 		return -EINVAL;

@@ -881,8 +879,6 @@ void ipipe_free_irq(struct ipipe_domain *ipd,
 {
 	unsigned long flags;
 
-	ipipe_root_only();
-
 	spin_lock_irqsave(&__ipipe_lock, flags);
 
 	if (ipd->irqs[irq].handler == NULL)

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

So either we have both request+enable and free usable over non-root, or there is no point.

Quoted 11 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

Quoted 2 lines

So either we have both request+enable and free usable over non-root, or there is no point.

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)
- in Xenomai 2.6 (at least, didn't check forge) as it calls with a hardened spin lock held into ipipe_virtualize_irq

Quoted 12 lines · Jan Kiszka

Quoted 11 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

Quoted 6 lines

Quoted 2 lines

So either we have both request+enable and free usable over non-root, or there is no point.

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

Quoted 2 lines

- in Xenomai 2.6 (at least, didn't check forge) as it calls with a hardened spin lock held into ipipe_virtualize_irq

Sorry, three bugs:
- in the RTDM spec as it always allowed rtdm_irq_request over RT task contexts

Jan

Quoted 12 lines · Jan Kiszka

Quoted 11 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

Quoted 6 lines

Quoted 2 lines

So either we have both request+enable and free usable over non-root, or there is no point.

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

Quoted 2 lines

- in Xenomai 2.6 (at least, didn't check forge) as it calls with a hardened spin lock held into ipipe_virtualize_irq

Sorry, three bugs:
- in the RTDM spec as it always allowed rtdm_irq_request over RT task contexts

Quoted 3 lines

Sorry, three bugs:
- in the RTDM spec as it always allowed rtdm_irq_request over RT task contexts

Changing the spec and adding a runtime check will likely be no issue. No sane driver should have made use of that option. I will file a patch.

Quoted 16 lines · Jan Kiszka

Quoted 15 lines · Jan Kiszka

Quoted 13 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

So either we have both request+enable and free usable over non-root, or there is no point.

Quoted 3 lines

Quoted 3 lines

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

I think this bug may only manifest over ARM as that arch does enable/disable_irq() inside __ipipe_enable/disable_irqdesc - unless something prevents that enabling will ever happen for interrupts that need Linux locks to work. Is that assured?

Quoted 16 lines · Jan Kiszka

Quoted 15 lines · Jan Kiszka

Quoted 13 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

So either we have both request+enable and free usable over non-root, or there is no point.

Quoted 3 lines

Quoted 3 lines

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

I think this bug may only manifest over ARM as that arch does enable/disable_irq() inside __ipipe_enable/disable_irqdesc - unless something prevents that enabling will ever happen for interrupts that need Linux locks to work. Is that assured?

Quoted 3 lines

Quoted 3 lines

- in Xenomai 2.6 (at least, didn't check forge) as it calls with a hardened spin lock held into ipipe_virtualize_irq

This problem is something I vaguely recall we discussed before already in the past. I think there was no good solution for the Xenomai 2 architecture.

In this light, let's remove those checks nevertheless. Enabling/disabling the IRQ are separate calls, and those should be instrumented as those cause the restriction.

Quoted 4 lines

Sorry, three bugs:
- in the RTDM spec as it always allowed rtdm_irq_request over RT task contexts

Changing the spec and adding a runtime check will likely be no issue. No sane driver should have made use of that option. I will file a patch.

Jan

Quoted 17 lines · Jan Kiszka

Quoted 16 lines · Jan Kiszka

Quoted 15 lines · Jan Kiszka

Quoted 13 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

So either we have both request+enable and free usable over non-root, or there is no point.

Quoted 8 lines

Quoted 3 lines

Quoted 3 lines

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

I think this bug may only manifest over ARM as that arch does enable/disable_irq() inside __ipipe_enable/disable_irqdesc - unless something prevents that enabling will ever happen for interrupts that need Linux locks to work. Is that assured?

ARM does that because otherwise interrupts are not enabled after a call to eg. rtdm_irq_request, and calling rtdm_irq_enable does not work, calling request_irq is required to get them working.

Quoted 21 lines · Jan Kiszka

Quoted 19 lines · Jan Kiszka

Quoted 18 lines · Jan Kiszka

Quoted 6 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Quoted 7 lines

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

So either we have both request+enable and free usable over non-root, or there is no point.

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

Quoted 4 lines

I think this bug may only manifest over ARM as that arch does enable/disable_irq() inside __ipipe_enable/disable_irqdesc - unless something prevents that enabling will ever happen for interrupts that need Linux locks to work. Is that assured?

I'm not referring to enable_irqdesc, but to the common programming pattern of calling ipipe_request_irq from the same context than ipipe_enable_irq (or directly the underlying irqchip handler for unmasking).

Quoted 9 lines

Quoted 4 lines

Quoted 4 lines

- in Xenomai 2.6 (at least, didn't check forge) as it calls with a hardened spin lock held into ipipe_virtualize_irq

This problem is something I vaguely recall we discussed before already in the past. I think there was no good solution for the Xenomai 2 architecture.

The main issue was about de-registering a handler, passing NULL. To solve the SMP-specific issue of interrupt synchronization on all CPUs, we would have to be able to disable the source, which may entail running regular code, therefore restricting the valid calling context to root.

Quoted 5 lines

In this light, let's remove those checks nevertheless. Enabling/disabling the IRQ are separate calls, and those should be instrumented as those cause the restriction.

I don't see it this way, because we can't predict what will be the constraints we might have for hooking irqs on all archs we will support. Maybe we will have to run more mainline code in some cases. In any case, we have to fold masking into the de-registration code for proper SMP support - this fix was never finalized precisely because we could not guarantee a root calling context in that case.

These checks are there to express the fact that calling from non-root is inherently unsafe. We might find a (ugly) way to tag irq descriptors, for knowing whether this is safe to call from non-root and test this conditionally. But at the end of the day, we would still end up with checking for arch-specific constraints in a generic API, which would be wrong by design.

I put these checks when refactoring the pipeline API for the very same reason than you agree to update the RTDM spec regarding
rtdm_request_irq: no sane code should have called ipipe_virtualize_irq() from a non-root context. This is just about formalizing this fact.

Quoted 27 lines · Philippe Gerum

Quoted 25 lines · Jan Kiszka

Quoted 13 lines · Jan Kiszka

Quoted 12 lines · Jan Kiszka

Quoted 11 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

Quoted 6 lines

Quoted 6 lines

Quoted 2 lines

So either we have both request+enable and free usable over non-root, or there is no point.

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

I think this bug may only manifest over ARM as that arch does enable/disable_irq() inside __ipipe_enable/disable_irqdesc - unless something prevents that enabling will ever happen for interrupts that need Linux locks to work. Is that assured?

Quoted 3 lines

I'm not referring to enable_irqdesc, but to the common programming pattern of calling ipipe_request_irq from the same context than ipipe_enable_irq (or directly the underlying irqchip handler for unmasking).

Patterns are better enforced at higher layers, not here.

Quoted 10 lines

Quoted 9 lines

Quoted 4 lines

Quoted 4 lines

- in Xenomai 2.6 (at least, didn't check forge) as it calls with a hardened spin lock held into ipipe_virtualize_irq

This problem is something I vaguely recall we discussed before already in the past. I think there was no good solution for the Xenomai 2 architecture.

Quoted 4 lines

The main issue was about de-registering a handler, passing NULL. To solve the SMP-specific issue of interrupt synchronization on all CPUs, we would have to be able to disable the source, which may entail running regular code, therefore restricting the valid calling context to root.

I'm not sure what the conclusion regarding this tricky topic was. But I don't see how this can be addressed only at I-pipe level anyway.

Quoted 21 lines

Quoted 6 lines

In this light, let's remove those checks nevertheless. Enabling/disabling the IRQ are separate calls, and those should be instrumented as those cause the restriction.

I don't see it this way, because we can't predict what will be the constraints we might have for hooking irqs on all archs we will support. Maybe we will have to run more mainline code in some cases. In any case, we have to fold masking into the de-registration code for proper SMP support - this fix was never finalized precisely because we could not guarantee a root calling context in that case.

These checks are there to express the fact that calling from non-root is inherently unsafe. We might find a (ugly) way to tag irq descriptors, for knowing whether this is safe to call from non-root and test this conditionally. But at the end of the day, we would still end up with checking for arch-specific constraints in a generic API, which would be wrong by design.

Quoted 4 lines

I put these checks when refactoring the pipeline API for the very same reason than you agree to update the RTDM spec regarding
rtdm_request_irq: no sane code should have called ipipe_virtualize_irq() from a non-root context. This is just about formalizing this fact.

...at the wrong point. Plus it is breaking our instrumentation. Again:
this belongs where we can asses the problem better, i.e. in the higher layer and in those functions that do break when called from RT context.

Jan

Quoted 29 lines · Gilles Chanteperdrix

Quoted 25 lines · Jan Kiszka

Quoted 13 lines · Jan Kiszka

Quoted 12 lines · Jan Kiszka

Quoted 11 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

Quoted 6 lines

Quoted 6 lines

Quoted 2 lines

So either we have both request+enable and free usable over non-root, or there is no point.

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

I think this bug may only manifest over ARM as that arch does enable/disable_irq() inside __ipipe_enable/disable_irqdesc - unless something prevents that enabling will ever happen for interrupts that need Linux locks to work. Is that assured?

Quoted 3 lines

ARM does that because otherwise interrupts are not enabled after a call to eg. rtdm_irq_request, and calling rtdm_irq_enable does not work, calling request_irq is required to get them working.

The generic pattern Xenomai currently uses is xnintr_attach + xnintr_enable. The latter happens to be rtdm_irq_enable as well. So, doesn't xnintr_enable work at all?

Or is it only not suited as interrupt
startup? Then, is that a new issue or something core-3.x specific? Finally, can't we address it in xnarch_enable_irq?

Quoted 30 lines · Jan Kiszka

Quoted 29 lines · Gilles Chanteperdrix

Quoted 25 lines · Jan Kiszka

Quoted 13 lines · Jan Kiszka

Quoted 12 lines · Jan Kiszka

Quoted 11 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

Quoted 6 lines

Quoted 6 lines

Quoted 2 lines

So either we have both request+enable and free usable over non-root, or there is no point.

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

I think this bug may only manifest over ARM as that arch does enable/disable_irq() inside __ipipe_enable/disable_irqdesc - unless something prevents that enabling will ever happen for interrupts that need Linux locks to work. Is that assured?

Quoted 7 lines

Quoted 3 lines

ARM does that because otherwise interrupts are not enabled after a call to eg. rtdm_irq_request, and calling rtdm_irq_enable does not work, calling request_irq is required to get them working.

The generic pattern Xenomai currently uses is xnintr_attach + xnintr_enable. The latter happens to be rtdm_irq_enable as well. So, doesn't xnintr_enable work at all?

No. It has in fact, never worked before the I-pipe core. People had to call request_irq before xnintr_attach.

Quoted 3 lines

Or is it only not suited as interrupt
startup? Then, is that a new issue or something core-3.x specific? Finally, can't we address it in xnarch_enable_irq?

This is a very old issue, that I had forgotten, and that bit me when I tried to use a separate timer for Xenomai and Linux on omap3: because the timer interrupt of a different timer has no corresponding linux interrupt.

The problem is that irqs which are also used by Linux have to be treated differently from irqs which are registered only for the linux domain.

Quoted 24 lines

Quoted 23 lines

Quoted 4 lines

In this light, let's remove those checks nevertheless. Enabling/disabling the IRQ are separate calls, and those should be instrumented as those cause the restriction.

I don't see it this way, because we can't predict what will be the constraints we might have for hooking irqs on all archs we will support. Maybe we will have to run more mainline code in some cases. In any case, we have to fold masking into the de-registration code for proper SMP support - this fix was never finalized precisely because we could not guarantee a root calling context in that case.

These checks are there to express the fact that calling from non-root is inherently unsafe. We might find a (ugly) way to tag irq descriptors, for knowing whether this is safe to call from non-root and test this conditionally. But at the end of the day, we would still end up with checking for arch-specific constraints in a generic API, which would be wrong by design.

I put these checks when refactoring the pipeline API for the very same reason than you agree to update the RTDM spec regarding
rtdm_request_irq: no sane code should have called ipipe_virtualize_irq() from a non-root context. This is just about formalizing this fact.

Quoted 3 lines

...at the wrong point. Plus it is breaking our instrumentation. Again:
this belongs where we can asses the problem better, i.e. in the higher layer and in those functions that do break when called from RT context.

I don't think so.

Quoted 51 lines · Gilles Chanteperdrix

Quoted 30 lines · Jan Kiszka

Quoted 29 lines · Gilles Chanteperdrix

Quoted 25 lines · Jan Kiszka

Quoted 13 lines · Jan Kiszka

Quoted 12 lines · Jan Kiszka

Quoted 11 lines · Philippe Gerum

Quoted 4 lines · Jan Kiszka

This reverts commit 073ff1e8045d0311b8cf390687c0ba3619681672.

Both service are NOT just root-only services. E.g., rtdm_irq_request requires by specification support also over non-Linux contexts.

Nack. We can't run the enable code for MSIs over non-root, and that code typically follows the irq request. Besides, we want to mask the source upon irq free to handle the SMP case properly, which we could not do from non-root with MSIs.

Quoted 6 lines

Quoted 6 lines

Quoted 2 lines

So either we have both request+enable and free usable over non-root, or there is no point.

OK, I get the point with legacy MSI. Then we have two other bugs to solve:
- in I-pipe as it holds a hardened spin lock across enable/disable (of MSIs)

I think this bug may only manifest over ARM as that arch does enable/disable_irq() inside __ipipe_enable/disable_irqdesc - unless something prevents that enabling will ever happen for interrupts that need Linux locks to work. Is that assured?

Quoted 7 lines

Quoted 3 lines

ARM does that because otherwise interrupts are not enabled after a call to eg. rtdm_irq_request, and calling rtdm_irq_enable does not work, calling request_irq is required to get them working.

The generic pattern Xenomai currently uses is xnintr_attach + xnintr_enable. The latter happens to be rtdm_irq_enable as well. So, doesn't xnintr_enable work at all?

No. It has in fact, never worked before the I-pipe core. People had to call request_irq before xnintr_attach.

Quoted 3 lines

Or is it only not suited as interrupt
startup? Then, is that a new issue or something core-3.x specific? Finally, can't we address it in xnarch_enable_irq?

This is a very old issue, that I had forgotten, and that bit me when I tried to use a separate timer for Xenomai and Linux on omap3: because the timer interrupt of a different timer has no corresponding linux interrupt.

Quoted 2 lines

The problem is that irqs which are also used by Linux have to be treated differently from irqs which are registered only for the linux domain.

OK. Then we can safely assume that this initial enabling/disabling will not cause excessive latencies or even acquire Linux locks on ARM, right?

Quoted 28 lines · Philippe Gerum

Quoted 27 lines

Quoted 19 lines

Quoted 4 lines

In this light, let's remove those checks nevertheless. Enabling/disabling the IRQ are separate calls, and those should be instrumented as those cause the restriction.

I don't see it this way, because we can't predict what will be the constraints we might have for hooking irqs on all archs we will support. Maybe we will have to run more mainline code in some cases. In any case, we have to fold masking into the de-registration code for proper SMP support - this fix was never finalized precisely because we could not guarantee a root calling context in that case.

These checks are there to express the fact that calling from non-root is inherently unsafe. We might find a (ugly) way to tag irq descriptors, for knowing whether this is safe to call from non-root and test this conditionally. But at the end of the day, we would still end up with checking for arch-specific constraints in a generic API, which would be wrong by design.

Quoted 4 lines

I put these checks when refactoring the pipeline API for the very same reason than you agree to update the RTDM spec regarding
rtdm_request_irq: no sane code should have called ipipe_virtualize_irq() from a non-root context. This is just about formalizing this fact.

...at the wrong point. Plus it is breaking our instrumentation. Again:
this belongs where we can asses the problem better, i.e. in the higher layer and in those functions that do break when called from RT context.

Quoted 1 line

I don't think so.

I do agree that the caller of ipipe_request_irq should not be called over RT context. However, ipipe_request_irq itself _is_ called under an RT spin lock with hardirqs disabled, both under Xenomai 2.6 and upcoming
3. And this triggers CONFIG_IPIPE_DEBUG_CONTEXT, clearly showing that things are still broken here. What do you suggest to fix all this?

Quoted 29 lines · Jan Kiszka

Quoted 28 lines · Philippe Gerum

Quoted 27 lines

Quoted 19 lines

Quoted 4 lines

In this light, let's remove those checks nevertheless. Enabling/disabling the IRQ are separate calls, and those should be instrumented as those cause the restriction.

I don't see it this way, because we can't predict what will be the constraints we might have for hooking irqs on all archs we will support. Maybe we will have to run more mainline code in some cases. In any case, we have to fold masking into the de-registration code for proper SMP support - this fix was never finalized precisely because we could not guarantee a root calling context in that case.

These checks are there to express the fact that calling from non-root is inherently unsafe. We might find a (ugly) way to tag irq descriptors, for knowing whether this is safe to call from non-root and test this conditionally. But at the end of the day, we would still end up with checking for arch-specific constraints in a generic API, which would be wrong by design.

Quoted 4 lines

I put these checks when refactoring the pipeline API for the very same reason than you agree to update the RTDM spec regarding
rtdm_request_irq: no sane code should have called ipipe_virtualize_irq() from a non-root context. This is just about formalizing this fact.

...at the wrong point. Plus it is breaking our instrumentation. Again:
this belongs where we can asses the problem better, i.e. in the higher layer and in those functions that do break when called from RT context.

Quoted 8 lines

Quoted 1 line

I don't think so.

I do agree that the caller of ipipe_request_irq should not be called over RT context. However, ipipe_request_irq itself _is_ called under an RT spin lock with hardirqs disabled, both under Xenomai 2.6 and upcoming
3. And this triggers CONFIG_IPIPE_DEBUG_CONTEXT, clearly showing that things are still broken here. What do you suggest to fix all this?

Fix the callers in the upcoming Xenomai releases, and provide an open coded implementation of ipipe_request_irq in ipipe_virtualize_irq when CONFIG_IPIPE_LEGACY is enabled, which will take care of the broken legacy.