On Wed, Jul 3, 2024 at 1:15 AM Edgecombe, Rick P <rick.p.edgecombe@xxxxxxxxx> wrote: > > On Tue, 2024-07-02 at 18:15 +0900, Masahiro Yamada wrote: > > > So there is no official way to build just a module to the output directory? > > > > > > You already know how to do it: > > > > #I'm guess it has something to do with the "M=" option because: > > #make ARCH=x86_64 O=../linux-tdx-kvm-out/ -j36 arch/x86/kvm/kvm.ko > > #arch/x86/kvm/kvm-intel.ko > > # > > #...works. > > This can build just the module, but not clean just the module. > > > > > > > > > > > > And > > > it just accidentally worked all these years? IMO it's a nice feature to > > > have. > > > I've especially found it useful when doing virtualization development where > > > you > > > need to build/test guest and host kernels as the same time. > > > > > > Or was it just now delegated to unofficial support after this patch? > > > > > > No. > > The M= option is intended for building external modules. > > You just abused it to build the upstream modules. > > > > Kbuild has never supported building external modules in a separate > > output directory. > > > > > > "delegated to unofficial support" is a wrong statement, > > as it has never officially supported in the past. > > > > > > Your way is a workaround that people found happened to work. > > The main point is that the old behavior was useful. It seems the change that > broke my workflow was intended to make it easier to maintain out-of-tree > modules? If so then aren't we taking away useful behavior for in-tree module > development to help out-of-tree modules? No. I never meant to prioritize the external module builds. I believe b1992c3772e69a6fd0e3fc81cd4d2820c8b6eca0 is the right thing to do. That's all. > Can you at least support VPATH method going forward? Although I am surprised I'm > the only one that hit this. I assumed this was a common usage. VPATH will be broken when a big change happens again for external module builds. That is what "unsupported" and "unofficial" mean. -- Best Regards Masahiro Yamada
