On Thu, Nov 30, 2023 at 10:52:17AM +0200, Jani Nikula wrote: > On Wed, 29 Nov 2023, Hamza Mahfooz <hamza.mahfooz@xxxxxxx> wrote: > > Cc: Nathan Chancellor <nathan@xxxxxxxxxx> > > > > On 11/29/23 13:12, Jani Nikula wrote: > >> At least the i915 and amd drivers enable a bunch more compiler warnings > >> than the kernel defaults. > >> > >> Extend the W=1 warnings to the entire drm subsystem by default. Use the > >> copy-pasted warnings from scripts/Makefile.extrawarn with > >> s/KBUILD_CFLAGS/subdir-ccflags-y/ to make it easier to compare and keep > >> up with them in the future. > >> > >> This is similar to the approach currently used in i915. > >> > >> Some of the -Wextra warnings do need to be disabled, just like in > >> Makefile.extrawarn, but take care to not disable them for W=2 or W=3 > >> builds, depending on the warning. > > > > I think this should go in after drm-misc-next has a clean build (for > > COMPILE_TEST builds) with this patch applied. Otherwise, it will break a > > lot of build configs. > > Oh, I'm absolutely not suggesting this should be merged before known > warnings have been addressed one way or another. Either by fixing them > or by disabling said warning in driver local Makefiles, depending on the > case. > > While I'm suggesting this, I obviously (I hope) can't take on fixing all > the warnings this exposes. One way to scale would be for folks to apply > this locally, see what it uncovers in their drivers, and fix some. > > As an intermediate step we might also apply this to a topic branch in > drm-tip, so you'd see the warnings when building drm-tip, but not in > indidual branches or in anything that's merged upstream. For what it's worth, I ran this through my personal build matrix with LLVM/clang and it only found a few instances of -Wunused-but-set-variable: drivers/gpu/drm/mediatek/mtk_disp_gamma.c:121:6: warning: variable 'cfg_val' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/nouveau/nouveau_svm.c:115:24: warning: variable 'priority' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/nouveau/nouveau_svm.c:929:6: warning: variable 'ret' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/nouveau/nvkm/subdev/acr/lsfw.c:221:7: warning: variable 'loc' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/qxl/qxl_cmd.c:424:6: warning: variable 'count' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/qxl/qxl_ioctl.c:148:14: warning: variable 'num_relocs' set but not used [-Wunused-but-set-variable] I know that clang does not support all the warnings that are being enabled here but I suspect there won't be too many instances of the other warnings. -Wformat-overflow and -Wformat-truncation might be the big ones. I know -Wstringop-overflow is being turned on globally in -next so that is one that you shouldn't have to worry much about. Cheers, Nathan
