On Wed, Jul 14, 2021 at 11:13 AM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote: > > On Sun, Jul 4, 2021 at 1:28 PM <ojeda@xxxxxxxxxx> wrote: > > > > From: Miguel Ojeda <ojeda@xxxxxxxxxx> > > > > To support Rust under GCC-built kernels, we need to save the flags that > > would have been passed if the kernel was being compiled with Clang. > > > > The reason is that `bindgen` -- the tool we use to generate Rust > > bindings to the C side of the kernel -- relies on `libclang` to > > parse C. Ideally: > > > > - `bindgen` would support a GCC backend (requested at [1]), > > > > - or the Clang driver would be perfectly compatible with GCC, > > including plugins. Unlikely, of course, but perhaps a big > > subset of configs may be possible to guarantee to be kept > > compatible nevertheless. > > > > This is also the reason why GCC builds are very experimental and some > > configurations may not work (e.g. `GCC_PLUGIN_RANDSTRUCT`). However, > > we keep GCC builds working (for some example configs) in the CI > > to avoid diverging/regressing further, so that we are better prepared > > for the future when a solution might become available. > > > > [1] https://github.com/rust-lang/rust-bindgen/issues/1949 > > > > Link: https://github.com/Rust-for-Linux/linux/issues/167 > > Co-developed-by: Alex Gaynor <alex.gaynor@xxxxxxxxx> > > Signed-off-by: Alex Gaynor <alex.gaynor@xxxxxxxxx> > > Co-developed-by: Geoffrey Thomas <geofft@xxxxxxxxxxxxx> > > Signed-off-by: Geoffrey Thomas <geofft@xxxxxxxxxxxxx> > > Co-developed-by: Finn Behrens <me@xxxxxxxxx> > > Signed-off-by: Finn Behrens <me@xxxxxxxxx> > > Co-developed-by: Adam Bratschi-Kaye <ark.email@xxxxxxxxx> > > Signed-off-by: Adam Bratschi-Kaye <ark.email@xxxxxxxxx> > > Co-developed-by: Wedson Almeida Filho <wedsonaf@xxxxxxxxxx> > > Signed-off-by: Wedson Almeida Filho <wedsonaf@xxxxxxxxxx> > > Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx> > > Patch LGTM; please keep an eye on the series: > https://lore.kernel.org/lkml/20210707224310.1403944-2-ndesaulniers@xxxxxxxxxx/ > > If that lands in kbuild before this, this patch will need to be > rebased to avoid a conflict in linux-next. > > So (tentatively :-P): > Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > If the patch needs to be rebased on the series linked above, please > drop my reviewed by tag and I will re-review. Perhaps putting me > explicitly on Cc: in the commit message will help notify me if there > are successive versions? > > > --- > > Makefile | 17 +++++++++++------ > > 1 file changed, 11 insertions(+), 6 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index 0565caea036..6e823d8bd64 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -573,18 +573,23 @@ endif > > # and from include/config/auto.conf.cmd to detect the compiler upgrade. > > CC_VERSION_TEXT = $(subst $(pound),,$(shell $(CC) --version 2>/dev/null | head -n 1)) > > > > -ifneq ($(findstring clang,$(CC_VERSION_TEXT)),) > > +TENTATIVE_CLANG_FLAGS := -Werror=unknown-warning-option Also, consider whether `BINDGEN_FLAGS` would be more descriptive (and less verbose) than `TENTATIVE_CLANG_FLAGS`. > > + > > ifneq ($(CROSS_COMPILE),) > > -CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) > > +TENTATIVE_CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) > > endif > > ifeq ($(LLVM_IAS),1) > > -CLANG_FLAGS += -integrated-as > > +TENTATIVE_CLANG_FLAGS += -integrated-as > > else > > -CLANG_FLAGS += -no-integrated-as > > +TENTATIVE_CLANG_FLAGS += -no-integrated-as > > GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) > > -CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) > > +TENTATIVE_CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) > > endif > > -CLANG_FLAGS += -Werror=unknown-warning-option > > + > > +export TENTATIVE_CLANG_FLAGS > > + > > +ifneq ($(findstring clang,$(CC_VERSION_TEXT)),) > > +CLANG_FLAGS += $(TENTATIVE_CLANG_FLAGS) > > KBUILD_CFLAGS += $(CLANG_FLAGS) > > KBUILD_AFLAGS += $(CLANG_FLAGS) > > export CLANG_FLAGS > > -- > > 2.32.0 > > > > > -- > Thanks, > ~Nick Desaulniers -- Thanks, ~Nick Desaulniers
