On Wed, Jan 10, 2024 at 10:12 PM Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, Jan 10, 2024 at 01:59:53PM +0800, richard clark wrote: > > A ported driver in linux kernel calls '__sync_val_compare_and_swap', > > That is a builtin function. It does not necessarily expand to an actual > function call. aarch64 will typically expand it to inline code. > native gcc version: gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0 cross-compiler gcc version: aarch64-linux-gnu-gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0 Interesting, the same '__sync_val_compare_and_swap' in the .c file will be 'U __aarch64_cas4_sync' in the .o file compiled by native, will be 't __cmpxchg_case_mb_32' in the .o file compiled by aarch64-linux-gnu-gcc... don't know what the reason is > > > the cross-compiler 'aarch64-linux-gnu-gcc' doesn't complain > > '__aarch64_cas1_sync' undefined reference, but the native compiler > > will complain. As Mark mentioned, I double check that both cross and > > native compiler should have ''-moutline-atomics' option enabled, do > > you know the reason for that? > > Ah, so you are requesting external functions. > > I am no aarch64 expert, but apparently there were some problems in > GCC 11, maybe that is what you saw? Or with some distros, anyway. > > It also matters if you have ARMv8.1-A enabled, the LSE instructions. > > Open a GCC bug report if you have more details? Thanks, > > > Segher
