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

[Philippe Mathieu-Daudé]

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 <f4bug@amsat.org>
---
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>

Clearly out of my understanding, but at least it links and the qtests
pass.
---
 configure | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/configure b/configure
index 06c03cebd3..3217aa22cb 100755
--- a/configure
+++ b/configure
@@ -2826,6 +2826,18 @@ else
   avx512f_opt="no"
 fi
 
+#########################################
+# Disable out-of-line atomic operations.
+
+case "$cpu" in
+  aarch64)
+    write_c_skeleton;
+    if compile_prog "$CPU_CFLAGS -Werror -mno-outline-atomics" "" ; then
+      CPU_CFLAGS="-mno-outline-atomics $CPU_CFLAGS"
+    fi
+    ;;
+esac
+
 ########################################
 # check if __[u]int128_t is usable.
 
-- 
2.34.1