Re: [OE-core] [PATCH] tclibc-baremetal.inc: fix gcc-cross EXTRA_OECONF

[Denys Dmytriyenko <denis@denix.org>]

On Tue, Sep 29, 2026 at 09:24:52AM +0200, Joerg Vehlow via lists.openembedded.org wrote:
> Using EXTRA_OECONF:pn-gcc-cross-${TARGET_ARCH}:append created a new override
> for EXTRA_OECONF, which led to almost all EXTRA_OECONF switches to be ignored.
> Furthermore, setting --without-headers here is not required,
> because it is set in gcc-cross.inc.

I fully realize this change has good intentions, but it actually breaks 
baremetal. We've been trying to debug this for the past couple of days.

While we run our baremetal in a multiconfig, you don't need that to reproduce 
the breakage only with OE-Core by adding these 2 lines to local.conf:

TCLIBC = "baremetal"
MACHINE = "qemuarm"

$ bitbake libgcc

| checking whether we are using the GNU C compiler... yes
| checking whether arm-oe-eabi-gcc  -mthumb -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a15 -D_TIME_BITS=64 -D_FILE_OFFSET_BITS=64 -no-pie -fno-PIE --sysroot=/OE/core-master/build/tmp/work/cortexa15t2hf-neon-oe-eabi/libgcc/16.2.0/recipe-sysroot accepts -g... yes
| checking for arm-oe-eabi-gcc  -mthumb -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a15 -D_TIME_BITS=64 -D_FILE_OFFSET_BITS=64 -no-pie -fno-PIE --sysroot=/OE/core-master/build/tmp/work/cortexa15t2hf-neon-oe-eabi/libgcc/16.2.0/recipe-sysroot option to accept ISO C89... unsupported
| checking how to run the C preprocessor... arm-oe-eabi-gcc -E --sysroot=/OE/core-master/build/tmp/work/cortexa15t2hf-neon-oe-eabi/libgcc/16.2.0/recipe-sysroot  -mthumb -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a15 -D_TIME_BITS=64 -D_FILE_OFFSET_BITS=64 -no-pie -fno-PIE
| configure: error: in `/OE/core-master/build/tmp/work/cortexa15t2hf-neon-oe-eabi/libgcc/16.2.0/gcc-16.2.0/build.arm-oe-eabi.arm-oe-eabi/libgcc':
| configure: error: C preprocessor "arm-oe-eabi-gcc -E --sysroot=/OE/core-master/build/tmp/work/cortexa15t2hf-neon-oe-eabi/libgcc/16.2.0/recipe-sysroot  -mthumb -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a15 -D_TIME_BITS=64 -D_FILE_OFFSET_BITS=64 -no-pie -fno-PIE" fails sanity check
| See `config.log' for more details

Reverting this single commit restores the working behavior.

I don't see anything suspicious in the config.log yet, but I'll keep digging.

Here's EXTRA_OECONF for gcc-cross-arm before and after the change:

EXTRA_OECONF=" \
--without-headers \
--disable-static \
--disable-nls \
--enable-initfini-array \
--without-headers \
"

EXTRA_OECONF=" \
--enable-clocale=generic \
--with-gnu-ld \
--enable-shared \
--enable-languages=c,c++ \
--disable-multilib \
--enable-default-pie \
--enable-c99 \
--enable-long-long \
--enable-symvers=gnu \
--enable-libstdcxx-pch \
--program-prefix=arm-oe-eabi- \
--without-local-prefix \
--disable-install-libiberty \
--disable-libssp \
--enable-libitm \
--enable-lto \
--disable-bootstrap \
--with-system-zlib \
--with-linker-hash-style=sysv \
--enable-linker-build-id \
--with-ppl=no \
--with-cloog=no \
--enable-checking=release \
--enable-cheaders=c_global \
--without-isl \
--with-gxx-include-dir=/not/exist/usr/include/c++/16.2.0 \
--with-gxx-libcxx-include-dir=/not/exist/usr/include/c++/v1 \
--with-sysroot=/not/exist \
--with-build-sysroot=/OE/core-master/build/tmp/work/x86_64-linux/gcc-cross-arm/16.2.0/recipe-sysroot \
--enable-poison-system-directories=error \
--with-system-zlib \
--disable-static \
--disable-nls \
--enable-initfini-array \
--without-headers \
"



> Signed-off-by: Joerg Vehlow <joerg.vehlow@emlix.com>
> ---
>  meta/conf/distro/include/tclibc-baremetal.inc | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/meta/conf/distro/include/tclibc-baremetal.inc b/meta/conf/distro/include/tclibc-baremetal.inc
> index abea5a7162..6043cb6654 100644
> --- a/meta/conf/distro/include/tclibc-baremetal.inc
> +++ b/meta/conf/distro/include/tclibc-baremetal.inc
> @@ -18,7 +18,6 @@ USE_NLS ?= "no"
>  IMAGE_LINGUAS = ""
>  LIBC_DEPENDENCIES = ""
>  
> -EXTRA_OECONF:pn-gcc-cross-${TARGET_ARCH}:append = " --without-headers"
>  DEPENDS:remove:pn-meta-toolchain = "virtual/libc virtual/compilerlibs"
>  
>  # certain compiler libs cannot be used without libc, avoid the dependence on compilerlibs