On Thu, May 30, 2024 at 05:50:52PM +0530, Naresh Kamboju wrote: > The arm builds failed on Linux next with gcc-13 and clang-18. > > Config: arm imx_v6_v7_defconfig - failed > > Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> > > Build log: > ----- > arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function > `rcu_trc_cmpxchg_need_qs': > update.c:(.text+0x348): undefined reference to `__bad_cmpxchg' > arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function > `rcu_read_unlock_trace_special': > update.c:(.text+0x41c): undefined reference to `__bad_cmpxchg' > arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function > `trc_read_check_handler': > update.c:(.text+0x4b0): undefined reference to `__bad_cmpxchg' > arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_inspect_reader': > update.c:(.text+0x1518): undefined reference to `__bad_cmpxchg' > arm-linux-gnueabihf-ld: update.c:(.text+0x1548): undefined reference > to `__bad_cmpxchg' > arm-linux-gnueabihf-ld: kernel/rcu/update.o:update.c:(.text+0x1cc4): > more undefined references to `__bad_cmpxchg' follow > make[3]: *** [/builds/linux/scripts/Makefile.vmlinux:34: vmlinux] Error 1 You get a reference to __bad_cmpxchg() when someone uses cmpxchg() on a datatype that there are no CPU instructions to perform the atomic compare-and-exchange. As we support 8-bit, 16-bit and 32-bit, I would expect that we're now seeing cmpxchg() being used on 64-bit values, which are unsupportable on 32-bit Arm. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
