On Tue, Feb 21, 2023, Yu Zhang wrote: > Thank you so much, Sean, for such a detailed guidance! > > Some questions below: > > On Fri, Feb 17, 2023 at 02:54:49PM -0800, Sean Christopherson wrote: > > Add a KVM x86 doc to the subsystem/maintainer handbook section to explain > > how KVM x86 (currently) operates as a sub-subsystem, and to soapbox on > > the rules and expectations for contributing to KVM x86. > > It's a fantastic doc! Also, many good requirements can be common in KVM, not > just KVM x86(e.g. the comment, changelog format, the testing requirement > etc.). Could we be greedier to ask our KVM maintainers for a generic handbook > of KVM, and maybe different sections for specific arches, which describe their > specific requirements(the base trees and branches, the maintaining processes > etc.)? :) At some point, yes, but my strong preference is to document the x86 side of things and then work from there. For KVM x86, I can mostly just say "these are the rules". Same goes for the other KVM arch maintainers (for their areas). Incorporating all of KVM would require a much more collaborative effort, which isn't a bad thing, but it will take more time and effort. And IMO, KVM x86 needs this typ eof documentation a lot more than the other KVM architectures, i.e. pushing out KVM x86 documentation in order to go for more comprehensive documentation is not a good tradeoff. > > +Trees > > +----- > > +KVM x86 is currently in a transition period from being part of the main KVM > > +tree, to being "just another KVM arch". As such, KVM x86 is split across the > > +main KVM tree, ``git.kernel.org/pub/scm/virt/kvm/kvm.git``, and a KVM x86 > > +specific tree, ``github.com/kvm-x86/linux.git``. > > Does other arch also have a specific tree? Yes. > If a patch series touches multiple archs(though the chance could be very > low), I guess that patch set should still be based on the main KVM tree? The > master branch or the next branch? Hmm, good question. Using kvm-86/next is likely the best answer in most cases. kvm/master is usually a bad choice because it won't have _any_ changes for the next release, i.e. using it as a base is more likely to yield conflicts. Similarly, kvm/queue and kvm/next are unlikely to have more relevant changes than kvm-x86/next. If there are non-trivial conflicts with multiple architectures then coordination between maintainers will be required no matter what base is used. And I would expect people sending those types of series to have enough experience to be able to make a judgment call and/or engage with maintainers to figure out the best solution. I'll rework the "Base Tree/Branch" to explicitly state that any series that primarily targets x86 should be based on kvm-x86/next, but with a "use common sense" qualifier. > > +Co-Posting Tests > > +~~~~~~~~~~~~~~~~ > > +KVM selftests that are associated with KVM changes, e.g. regression tests for > > +bug fixes, should be posted along with the KVM changes as a single series. > > + > > +KVM-unit-tests should *always* be posted separately. Tools, e.g. b4 am, don't > > +know that KVM-unit-tests is a separate repository and get confused when patches > > +in a series apply on different trees. To tie KVM-unit-tests patches back to > > +KVM patches, first post the KVM changes and then provide a lore Link: to the > > +KVM patch/series in the KVM-unit-tests patch(es). > > I wonder, for KVM bugzilla to report a bug, or for our QAs to perform regular > tests using KVM selftests/KVM-unit-tests, which tree/branch is more reasonable > to be based on? > > E.g., I saw some bugzilla issues earlier, reporting failures of some unit tests, > did some investigation, yet to find those failures were just because the corresponding > KVM patches had not been merged yet. > > Maybe we also should take care of the timings of the merging of KVM patches and > the test patches? I really don't want to hold up KVM-unit-test patches waiting for KVM fixes to be merged. KUT is already woefully under-maintained, artificially holding up patches will only make things worse. And simply waiting for patches to land in KVM doesn't necessarily solve things either, e.g. if the fixes land in kvm/master mid-cycle then running against kvm/next will continue to fail. Waiting also doesn't help people running KUT against older kernels, e.g. for qualifying stable kernels. I completely understand the pain, but unfortunately no one has come up with an elegant, low-maintenance solution (this problem has been discussed multiple times in the past). > Two examples(I'm sure there're more :)): > 1> https://bugzilla.kernel.org/show_bug.cgi?id=216812 > 2> https://bugzilla.kernel.org/show_bug.cgi?id=216725 > > > B.R. > Yu >
