On 10.11.21 08:38, Philippe Gerum wrote: > > Jan Kiszka <jan.kis...@siemens.com> writes: > >> On 09.11.21 14:35, Philippe Gerum wrote: >>> >>> Jan Kiszka <jan.kis...@siemens.com> writes: >>> >>>> On 09.11.21 11:23, Philippe Gerum wrote: >>>>> >>>>> Jan Kiszka <jan.kis...@siemens.com> writes: >>>>> >>>>>> On 08.11.21 18:57, Philippe Gerum wrote: >>>>>>> >>>>>>> Jan Kiszka <jan.kis...@siemens.com> 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. > >> 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. 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. Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux
