On 10.11.21 09:58, Philippe Gerum wrote: > > Jan Kiszka <[email protected]> writes: > >> On 10.11.21 08:38, Philippe Gerum wrote: >>> >>> Jan Kiszka <[email protected]> writes: >>> >>>> On 09.11.21 14:35, Philippe Gerum wrote: >>>>> >>>>> Jan Kiszka <[email protected]> writes: >>>>> >>>>>> On 09.11.21 11:23, Philippe Gerum wrote: >>>>>>> >>>>>>> Jan Kiszka <[email protected]> writes: >>>>>>> >>>>>>>> On 08.11.21 18:57, Philippe Gerum wrote: >>>>>>>>> >>>>>>>>> Jan Kiszka <[email protected]> writes: >>>>>>>>> >>>>>>>>>> Hi Philippe, >>>>>>>>>> >>>>>>>>>> this dovetail commit makes the pipeline go red, crashing the kernels >>>>>>>>>> (e.g. [1][2]). I hope this is something we can quickly fix in >>>>>>>>>> dovetail, >>>>>>>>>> maybe via a config option? >>>>>>>>>> >>>>>>>>>> Jan >>>>>>>>>> >>>>>>>>>> [1] https://source.denx.de/Xenomai/xenomai-images/-/jobs/348118#L966 >>>>>>>>>> [2] https://source.denx.de/Xenomai/xenomai-images/-/jobs/348121#L1429 >>>>>>>>> >>>>>>>>> Cobalt needs some update to cope with this now. I'll send a fix either >>>>>>>>> way (dovetail or xenomai) tomorrow morning. >>>>>>>> >>>>>>>> This should be fixed in dovetail - API breakage. We can update Xenomai >>>>>>>> later, along with enabling this feature again. >>>>>>>> >>>>>>> >>>>>>> We now have a change in the Dovetail tree which handles the fact that >>>>>>> some Dovetail-based core might lag behind a bit API-wise regarding the >>>>>>> new prctl-based call form. Since this simplifies the handling for any >>>>>>> companion core in that particular case, this seems legitimate to add >>>>>>> it. Tested on kvm-x86, -aarch64, and i.MX6-sabre with both Cobalt and >>>>>>> EVL cores. Both test suites run properly, so far so good. >>>>>> >>>>>> I'm not against this change, but activating it is no Xenomai 3.2 >>>>>> material as it will break the ABI. >>>>> >>>>> No, the ABI has never been affected by this series, the old call form >>>>> Cobalt uses is still supported, the new prctl() call form is a mere >>>>> addition, not a replacement. The problem did only affect the kernel >>>>> interface between the pipeline core and Cobalt, which is strictly a >>>>> kernel API issue, not revealed by my tests mainly with Xenomai4/EVL >>>>> unfortunately. >>>> >>>> The whole purpose of having this addition is using it. And that does >>>> make a lot of sense, as you described. So the plan is to activate AND >>>> use this feature in Xenomai 3.3 - with the aforementioned impact on the >>>> ABI. >>>> >>>> Xenomai 3.2 will continue to use the old syscall range extension scheme, >>>> thus as no need and no desire to enable reporting of prctl calls to the >>>> core. Therefore, Dovetail should continue to refrain from doing that for >>>> Xenomai 3.2. The easiest way to achieve that is making the extension >>>> build-time configurable. Other cores can then still enable it for their >>>> *use*, and the fresh Xenomai 3.2 release will not break over the next >>>> dovetail patch revision (which is urgently needed do to the apic-ack fix). >>>> >>>> Makes sense? >>>> >>> >>> It falls short of solving the real problem. >> >> Nor does your approach. If it were consequently ignoring stable >> interfaces - there is no need for it in your in-tree model -, it would >> have simply dropped the old syscall interface. Instead, it only provided >> a half-stable solution for its users. >> > > It looks ok so far on this end, thanks for caring anyway. > >>> >>>> I really like to avoid avoid diverging developments again, but stability >>>> trumps features and would enforce this if we cannot find a better solution. >>>> >>> >>> I agree, the best way is to decouple the code bases at this point, so >>> that all development efforts can progress at their own pace, according >>> to their own agenda and schedule, which are not compatible. Opening a >>> new tree for maintaining a Xenomai3-specific pipeline will: >>> >>> - make things clearer to Xenomai3 users, providing them an unambiguous >>> source for getting Dovetail support that works for it. >>> >>> - give you full control over this Dovetail tree, what goes there from >>> the upstream code and what does not, when it does if it does. >>> >>> - keep all options open for the Dovetail upstream development. The >>> whole point of starting Dovetail was to be able to evolve the dual >>> kernel integration technique based on the evolving implementation of >>> the mainline kernel, instead of being stuck for ages with legacy >>> kernel interfaces. Kernel API changes are part of this process. >>> >>> We can cross-pollinate the trees, until Xenomai3 rebases on the next >>> linux SLTS release which Dovetail upstream would support, and so on. >>> >> >> As I said, this is very unfortunate, and I hope you will reconsider your >> decisions. >> > > I don't think this is a bad thing. This clarifies the intent, making > things easier in the long run. > >> Meanwhile, I will stop 5.10.y-dovetail and instead start >> linux-dovetail-stable.git with related branches. CI will be migrated as >> well, stopping coverage of linux-dovetail head. > > Please call it linux-xenomai3-dovetail or anything you see fit except > linux-dovetail-stable. Stability has a different meaning, and this name > should be reserved for an upstream Dovetail tree. TIA, >
The result will not be Xenomai 3 specific. It will just use stable APIs as additional requirement, perform the merge-based development process for stable branches and provide regular CI-qualified releases again. Just like under I-pipe. Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux
