Re: [PATCH v2 4/8] configure: Disable out-of-line atomic operations on Aarch64

[Richard Henderson]

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.


r~