On Wed, Mar 22, 2023 at 1:49 PM Kalle Valo <kvalo@xxxxxxxxxx> wrote: > > Nathan Chancellor <nathan@xxxxxxxxxx> writes: > > > On Mon, Mar 20, 2023 at 11:26:17AM -0700, Linus Torvalds wrote: > >> On Mon, Mar 20, 2023 at 11:05 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > >> > > >> > On the clang front, I am still seeing the following warning turned error > >> > for arm64 allmodconfig at least: > >> > > >> > drivers/gpu/host1x/dev.c:520:6: error: variable 'syncpt_irq' is uninitialized when used here [-Werror,-Wuninitialized] > >> > if (syncpt_irq < 0) > >> > ^~~~~~~~~~ > >> > >> Hmm. I do my arm64 allmodconfig builds with gcc, and I'm surprised > >> that gcc doesn't warn about this. > > > > Perhaps these would make doing allmodconfig builds with clang more > > frequently less painful for you? > > > > https://lore.kernel.org/llvm/20230319235619.GA18547@dev-arch.thelio-3990X/ > > Thank you, at least for me this is really helpful. I tried now clang for > the first time but seeing a strange problem. > > I prefer to define the compiler in GNUmakefile so it's easy to change > compilers and I don't need to remember the exact command line. So I have > this in the top level GNUmakefile (all the rest commented out): > > LLVM=/opt/clang/llvm-16.0.0/bin/ > Welcome to the LLVM/Clang world! First try - First Cry... In my build-environment I add (export) /path/to/llvm/bin to $PATH and pass single CC LD AR etc. (what is substituted by LLVM=1): make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \ OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump READELF=llvm-readelf \ HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar HOSTLD=ld.lld Equivalent to: make LLVM=1 I cannot comment on `make LLVM=/path/to/llvm/` and/or combinations with `LLVM=1` as I have never used it > If I run 'make oldconfig' it seems to use clang but after I run just > 'make' it seems to switch back to the host GCC compiler and ask for GCC > specific config questions again. Workaround for this seems to be adding > 'export LLVM' to GNUmakefile, after that also 'make' uses clang as > expected. > You have to pass `make LLVM=1` in any case... to `oldconfig` or when adding any MAKEFLAGS like -j${number-of-available-cpus}. Hope that helps. Best regards, -Sedat- [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/kbuild/llvm.rst [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/kbuild/llvm.rst#n52
