On Tue, Oct 6, 2020 at 6:08 AM Andrew Lunn <andrew@xxxxxxx> wrote: > > > It depends a lot on what portion of the kernel gets enabled for W=1. > > > > As long as it's only drivers that are actively maintained, and they > > make up a fairly small portion of all code, it should not be a problem > > to find someone to fix useful warnings. > > Well, drivers/net/ethernet is around 1.5M LOC. The tree as a whole is > just short of 23M LOC. So i guess that is a small portion of all the > code. > > Andrew I am not a big fan of KBUILD_CFLAGS_W1_<timestamp> since it is ugly. I'd like to start with adding individual flags like drivers/gpu/drm/i915/Makefile, and see how difficult it would be to maintain it. One drawback of your approach is that you cannot set KBUILD_CFLAGS_W1_20200930 until you eliminate all the warnings in the sub-directory in interest. (i.e. all or nothing approach) At best, you can only work out from 'old -> new' order because KBUILD_CFLAGS_W1_20200326 is a suer-set of KBUILD_CFLAGS_W1_20190907, which is a suer-set of KBUILD_CFLAGS_W1_20190617 ... If you add flags individually, you can start with low-hanging fruits, or ones with higher priority as Arnd mentions about -Wmissing-{declaration,prototypes}. For example, you might be able to set 'subdir-ccflags-y += -Wmissing-declarations' to drivers/net/Makefile, while 'subdir-ccflags-y += -Wunused-but-set-variable' stays in drivers/net/ethernet/Makefile. -- Best Regards Masahiro Yamada