* Richard Henderson:
> On 9/26/18 1:59 AM, Florian Weimer wrote:
>> * rth:
>>
>>> diff --git a/libgcc/config/aarch64/lse.c b/libgcc/config/aarch64/lse.c
>>> new file mode 100644
>>> index 00000000000..20f4bde741f
>>> --- /dev/null
>>> +++ b/libgcc/config/aarch64/lse.c
>>
>>> +static void __attribute__((constructor))
>>> +init_have_atomics(void)
>>> +{
>>> + unsigned long hwcap = getauxval(AT_HWCAP);
>>> + __aa64_have_atomics = (hwcap & HWCAP_ATOMICS) != 0;
>>> +}
>>
>> Is there an expectation that it is possible to use the atomics in IFUNC
>> resolvers? Then this needs an explanation why it is safe to run with
>> the other kind of atomics until the initialization of
>> __aa64_have_atomics has happened.
>
> Yes. The explanation is simple, in that the !have_atomics path is
> also atomic. It will simply use the slower load/store-exclusive path.
>
> Perhaps, despite the official ARMv8.1-Atomics name, LSE was in fact a
> better choice for a name after all, as its lack does not imply a lack
> of atomicity. And a comment, to be sure.
That's not what I meant. I'm curious if LSE and non-LSE atomics on the
same location will still result in the expected memory ordering. If
they don't, then this requires *some* explanation why this is okay.
Thanks,
Florian
