When build Xen target with Clang, the linker reports failure.
This patch adds the related info in the documentation as a known issue and gives details for how to dismiss the building failure with Clang.
Signed-off-by: Leo Yan leo.yan@linaro.org --- doc/build/clang.rst | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)
diff --git a/doc/build/clang.rst b/doc/build/clang.rst index 1d35616eb5..cc265506c2 100644 --- a/doc/build/clang.rst +++ b/doc/build/clang.rst @@ -74,3 +74,39 @@ simplified with a simple wrapper script - saved as
#!/bin/sh exec clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd "$@" + + +Known Issues +------------ + +When build U-boot for `xenguest_arm64_defconfig` target, it reports linkage +error: + +.. code-block:: bash + + aarch64-linux-gnu-ld.bfd: drivers/xen/hypervisor.o: in function `do_hypervisor_callback': + /home/leoy/Dev2/u-boot/drivers/xen/hypervisor.c:188: undefined reference to `__aarch64_swp8_acq_rel' + aarch64-linux-gnu-ld.bfd: drivers/xen/hypervisor.o: in function `synch_test_and_set_bit': + /home/leoy/Dev2/u-boot/./arch/arm/include/asm/xen/system.h:40: undefined reference to `__aarch64_ldset1_acq_rel' + aarch64-linux-gnu-ld.bfd: drivers/xen/hypervisor.o: in function `synch_test_and_clear_bit': + /home/leoy/Dev2/u-boot/./arch/arm/include/asm/xen/system.h:28: undefined reference to `__aarch64_ldclr1_acq_rel' + aarch64-linux-gnu-ld.bfd: drivers/xen/hypervisor.o: in function `synch_test_and_set_bit': + /home/leoy/Dev2/u-boot/./arch/arm/include/asm/xen/system.h:40: undefined reference to `__aarch64_ldset1_acq_rel' + aarch64-linux-gnu-ld.bfd: drivers/xen/hypervisor.o: in function `synch_test_and_clear_bit': + /home/leoy/Dev2/u-boot/./arch/arm/include/asm/xen/system.h:28: undefined reference to `__aarch64_ldclr1_acq_rel' + aarch64-linux-gnu-ld.bfd: drivers/xen/events.o: in function `synch_test_and_clear_bit': + /home/leoy/Dev2/u-boot/./arch/arm/include/asm/xen/system.h:28: undefined reference to `__aarch64_ldclr1_acq_rel' + aarch64-linux-gnu-ld.bfd: drivers/xen/events.o: in function `synch_test_and_set_bit': + /home/leoy/Dev2/u-boot/./arch/arm/include/asm/xen/system.h:40: undefined reference to `__aarch64_ldset1_acq_rel' + aarch64-linux-gnu-ld.bfd: drivers/xen/gnttab.o: in function `gnttab_end_access': + /home/leoy/Dev2/u-boot/drivers/xen/gnttab.c:109: undefined reference to `__aarch64_cas2_acq_rel' + Segmentation fault + +To fix the failure, we need to append option `-mno-outline-atomics` in Clang +command to not generate local calls to out-of-line atomic operations: + +.. code-block:: bash + + make HOSTCC=clang xenguest_arm64_defconfig + make HOSTCC=clang CROSS_COMPILE=aarch64-linux-gnu- \ + CC="clang -target aarch64-linux-gnueabi -mno-outline-atomics" -j8