On Wed, Mar 22, 2023 at 09:36:37AM -0700, Nathan Chancellor wrote: > On Wed, Mar 22, 2023 at 02:44:47PM +0200, Kalle Valo 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. > > Really glad to hear! I hope this helps make testing and verifying > changes with clang and LLVM easier for developers and maintainers. > > > 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/ > > > > 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. > > Interesting... I just tested with a basic GNUmakefile and everything > seems to work fine without an export. At the same time, the export > should not hurt anything, so as long as it works, that is what matters. Ah, the export is needed so that mixed-build works properly (see lines 324 to 361 in Makefile), as 'make' will be called to process each target individually; without the export, LLVM is not set for the subsequent 'make' calls, so gcc is called. I just saw the same behavior as you did while testing with $ make -j(nproc) clean defconfig all without the export (GCC was used instead of LLVM). > $ gcc --version > fish: Unknown command: gcc > > > $ fd -t x . $CBL_TC_LLVM_STORE/16.0.0/bin -x basename > clang-16 > llvm-nm > llvm-objdump > llvm-objcopy > llvm-symbolizer > llvm-strings > llvm-readobj > llvm-dwarfdump > lld > llvm-ar > > > $ cat GNUmakefile > LLVM := $(CBL_TC_LLVM_STORE)/16.0.0/bin/ > > include Makefile > > > $ make -sj(nproc) defconfig > > > $ head -13 .config > # > # Automatically generated file; DO NOT EDIT. > # Linux/x86 6.3.0-rc3 Kernel Configuration > # > CONFIG_CC_VERSION_TEXT="ClangBuiltLinux clang version 16.0.0" > CONFIG_GCC_VERSION=0 > CONFIG_CC_IS_CLANG=y > CONFIG_CLANG_VERSION=160000 > CONFIG_AS_IS_LLVM=y > CONFIG_AS_VERSION=160000 > CONFIG_LD_VERSION=0 > CONFIG_LD_IS_LLD=y > CONFIG_LLD_VERSION=160000 > > > $ make -sj(nproc) init/main.o > > > $ $CBL_TC_LLVM_STORE/16.0.0/bin/llvm-readelf -p .comment init/main.o > String dump of section '.comment': > [ 1] ClangBuiltLinux clang version 16.0.0 > > > I added an informational print and I always saw the correct value: > > diff --git a/Makefile b/Makefile > index a2c310df2145..070394c4cb8c 100644 > --- a/Makefile > +++ b/Makefile > @@ -431,6 +431,7 @@ HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null) > HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null) > > ifneq ($(LLVM),) > +$(info LLVM: $(LLVM)) > ifneq ($(filter %/,$(LLVM)),) > LLVM_PREFIX := $(LLVM) > else ifneq ($(filter -%,$(LLVM)),) > > If you have any further issues, please do not hesitate to reach out! > > Cheers, > Nathan >
