Hi Tom,
On Tue, Sep 27, 2022 at 8:57 AM Tom Rini trini@konsulko.com wrote:
On Mon, Sep 26, 2022 at 08:47:47PM +0000, Alistair Delva wrote:
The LLVM toolchain does not have or need libgcc, so do not require it to exist on the library path. Even if "-print-libgcc-file-name" returned the empty string, -lgcc would be specified.
This leaves CONFIG_USE_PRIVATE_LIBGCC alone because I did not have a target/toolchain combination available for testing.
Signed-off-by: Alistair Delva adelva@google.com Cc: Simon Glass sjg@chromium.org Cc: Tom Rini trini@konsulko.com Cc: Nick Desaulniers ndesaulniers@google.com
Makefile | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/Makefile b/Makefile index 8af67ebd63..af06b7aa19 100644 --- a/Makefile +++ b/Makefile @@ -874,8 +874,10 @@ u-boot-main := $(libs-y) ifeq ($(CONFIG_USE_PRIVATE_LIBGCC),y) PLATFORM_LIBGCC = arch/$(ARCH)/lib/lib.a else +ifneq ($(cc-name),clang) PLATFORM_LIBGCC := -L $(shell dirname `$(CC) $(c_flags) -print-libgcc-file-name`) -lgcc endif +endif PLATFORM_LIBS += $(PLATFORM_LIBGCC)
ifdef CONFIG_CC_COVERAGE
So this one isn't quite right, and will result in some platforms / architectures just failing to build as the handful of functions we get provided by CONFIG_USE_PRIVATE_LIBGCC end up being missing.
It's also the case that this is a badly named option, and something we really should figure out how to remove and then always provide the required functions for. What configuration did you end up having this problem on exactly?
We have CI set up for qemu_arm64_defconfig, qemu-x86_64_defconfig, am57xx_evm_defconfig and rock-pi-4-rk3399_defconfig. I think all were affected, since they don't use CONFIG_USE_PRIVATE_LIBGCC, so they all hit this fallback.
AFAIK, for a long time, Android used an LLVM toolchain built with some workarounds such as knowledge of a corresponding GCC-based toolchain, so -print-libgcc-file-name could provide a path to libgcc.a. However, our newer toolchains no longer do this and the symbols are either automatically provided or provided by compiler-rt. In U-Boot's case, I don't think our targets ever required libgcc but because the fall-through expands to "-L . -lgcc" when -print-libgcc-file-name returns the empty string, the link will fail because it will look for libgcc but not find it.
Alistair.