On Mon, Nov 26, 2018 at 8:31 AM Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > > Hi Randy, > > > On Tue, Nov 20, 2018 at 5:51 AM Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote: > > > > Hi Yamada-san, > > > > There was recently a netfilter build error in linux-next for which > > a patch was posted by Taehee Yoo. The patch works (fixes the build > > error) but I don't see how or why. > > > > My build error report is here: > > https://lore.kernel.org/lkml/fa7a7824-44df-c058-dba2-ec29c5028361@xxxxxxxxxxxxx/T/#u > > > > > > Would you take a look at it and try to explain why the patch works? > > > > The patch's email thread begins here: > > https://www.spinics.net/lists/netfilter-devel/msg56985.html > > > I think this is a bug of Kconfig. > > I sent a patch. > https://patchwork.kernel.org/patch/10697637/ > > > -- > Best Regards > Masahiro Yamada I always understood this behavior as intentional. Say that a high-level arch symbol has 'select FOO_HELPERS if FOO' for example, where both FOO and FOO_HELPERS can be compiled as modules. The intention there is probably to make sure that FOO_HELPERS is available whenever FOO is (FOO_HELPERS must be >= FOO). If FOO is y, then FOO_HELPERS must be y. If FOO is m, then it's fine for FOO_HELPERS to be m (but not n), because it can be loaded as needed whenever FOO is. Forcing FOO_HELPERS to y would remove the possibility to compile it as a module. I suspect some things rely on this (and that some other symbols just automagically act in a reasonable way even though it wasn't planned). And yeah, there might be better ways to handle that particular case, but going for concepts. :) Cheers, Ulf
