On 16/2/22 17:42, Akihiko Odaki wrote:
On 2022/02/17 0:08, Philippe Mathieu-Daudé wrote:
On 16/2/22 11:19, Richard Henderson wrote:
On 2/16/22 04:01, Philippe Mathieu-Daudé via wrote:
GCC 10.1 introduced the -moutline-atomics option on Aarch64.
This options is enabled by default, and triggers a link failure:
Undefined symbols for architecture arm64:
"___aarch64_cas1_acq_rel", referenced from:
_qmp_migrate_recover in migration_migration.c.o
_cpu_atomic_cmpxchgb_mmu in accel_tcg_cputlb.c.o
_cpu_atomic_fetch_sminb_mmu in accel_tcg_cputlb.c.o
_cpu_atomic_fetch_uminb_mmu in accel_tcg_cputlb.c.o
_cpu_atomic_fetch_smaxb_mmu in accel_tcg_cputlb.c.o
_cpu_atomic_fetch_umaxb_mmu in accel_tcg_cputlb.c.o
_cpu_atomic_smin_fetchb_mmu in accel_tcg_cputlb.c.o
...
"___aarch64_ldadd4_acq_rel", referenced from:
_multifd_recv_new_channel in migration_multifd.c.o
_monitor_event in monitor_hmp.c.o
_handle_hmp_command in monitor_hmp.c.o
_colo_compare_finalize in net_colo-compare.c.o
_flatview_unref in softmmu_memory.c.o
_virtio_scsi_hotunplug in hw_scsi_virtio-scsi.c.o
_tcg_register_thread in tcg_tcg.c.o
...
"___aarch64_swp4_acq", referenced from:
_qemu_spin_lock in softmmu_cpu-timers.c.o
_cpu_get_ticks in softmmu_cpu-timers.c.o
_qemu_spin_lock in softmmu_icount.c.o
_cpu_exec in accel_tcg_cpu-exec.c.o
_page_flush_tb_1.isra.0 in accel_tcg_translate-all.c.o
_page_entry_lock in accel_tcg_translate-all.c.o
_do_tb_phys_invalidate in accel_tcg_translate-all.c.o
...
QEMU implements its own atomic operations using C11 builtin helpers.
Disable the GCC out-of-line atomic ops.
Signed-off-by: Philippe Mathieu-Daudé<f4...@amsat.org>
---
Cc: Stefan Hajnoczi<stefa...@redhat.com>
Cc: Paolo Bonzini<pbonz...@redhat.com>
Clearly out of my understanding, but at least it links and the qtests
pass.
---
configure | 12 ++++++++++++
1 file changed, 12 insertions(+)
These should have been supplied by libgcc.a, which we're supposed to
be linking against. Something is wrong with your installation.
I don't have gobjc/g++ installed, so ./configure defaulted to Clang to
compile these languages, but compiled C files using GCC. At the end the
Clang linker is used (the default c++ symlink).
Could there be a mismatch between Clang (-mno-outline-atomics) and GCC
(-moutline-atomics)?
I think you have to instruct Clang to use libgcc instead of compiler-rt
and link the objects with GCC. Here is the documentation of Clang about
the runtime I could find:
https://clang.llvm.org/docs/Toolchain.html#libgcc-s-gnu
Thanks for the pointer. And the next section is
https://clang.llvm.org/docs/Toolchain.html#atomics-library :)
Clang does not currently automatically link against libatomic when
using libgcc_s. You may need to manually add -latomic to support
this configuration when using non-native atomic operations (if you
see link errors referring to __atomic_* functions).
I'll try that.
