On Wed, Jul 13, 2022 at 3:44 AM Ren Zhijie <renzhijie2@xxxxxxxxxx> wrote: > 在 2022/7/12 16:27, Arnd Bergmann 写道: > > Thanks for your suggestion. > > How does it to fix the implicit-function-declaration error? > I missed that part at first. I would say the #ifdef around the declarations in the header should be removed here, it serves no purpose, and it is safe to rely on the compiler to perform dead code elimination so this does not lead to a link error even if a dead function references another function that is not reachable. Arnd