Re: Question about atomics

[Richard Henderson]

On 3/13/22 21:09, Warner Losh wrote:
> Oh? Out of paranoia, how can I verify that this is the case when compiled on 
> FreeBSD?
> Perhaps the atomic sequence FreeBSD uses differs a little from Linux and we 
> don't trigger
> that code?

$ objdump -dr libqemu-arm-*-user.fa.p/accel_tcg_user-exec.c.o

0000000000001490 <helper_atomic_cmpxchgl_le>:
...
    14b7:       e8 04 ec ff ff          callq  c0 
<atomic_mmu_lookup.constprop.0>
    14bc:       48 89 c2                mov    %rax,%rdx
    14bf:       44 89 e0                mov    %r12d,%eax
    14c2:       f0 44 0f b1 32          lock cmpxchg %r14d,(%rdx)


r~