Re: [edk2-devel] [PATCH] MdePkg/Include: AARCH64: disable outline atomics on GCC 10.2+

["Ard Biesheuvel" <ard.biesheuvel@arm.com>]

On 5/29/20 4:29 PM, Gao, Liming wrote:
> Ard:
> 
>> -----Original Message-----
>> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Ard Biesheuvel
>> Sent: Friday, May 29, 2020 1:47 PM
>> To: devel@edk2.groups.io; Gao, Liming <liming.gao@intel.com>; lersek@redhat.com; Leif Lindholm <leif@nuviainc.com>
>> Cc: philmd@redhat.com; mliska@suse.cz
>> Subject: Re: [edk2-devel] [PATCH] MdePkg/Include: AARCH64: disable outline atomics on GCC 10.2+
>>
>> On 5/29/20 5:18 AM, Liming Gao via groups.io wrote:
>>> Leif:
>>>    I get the point that the linux distribution default GCC version may be 10 or above. Without this fix, those developers can’t pass
>> build edk2-stable202005. So, you think this is a critical issue to catch stable tag 202005.
>>>
>>> Ard:
>>>     For this patch, I have two minor comments.
>>> 1) I suggest to remove Link: https://bugzilla.tianocore.org/show_bug.cgi?id=2723 from comments, because this information has
>> been in the commit message.
>>
>> I think it would be helpful to keep it but I won't insist.
>>
> 
> I agree this is useful. But, we record it in the commit message. I prefer to remove this link from source code.
> With this change, Reviewed-by: Liming Gao <liming.gao@intel.com>
> 


Works for me.

I will send a v2 after the stable tag is released.


>>> 2) Can we think __GNUC_MINOR__ is always defined? Do we need to check its value after check whether it is defined or not?
>>>
>>
>> Yes __GNUC_MINOR__ is always defined.
>>
>>
>>
>>> -----Original Message-----
>>> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Laszlo Ersek
>>> Sent: 2020年5月29日 4:03
>>> To: Leif Lindholm <leif@nuviainc.com>
>>> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>; devel@edk2.groups.io; Gao, Liming <liming.gao@intel.com>; philmd@redhat.com;
>> mliska@suse.cz
>>> Subject: Re: [edk2-devel] [PATCH] MdePkg/Include: AARCH64: disable outline atomics on GCC 10.2+
>>>
>>> On 05/28/20 12:05, Leif Lindholm wrote:
>>>> On Wed, May 27, 2020 at 11:12:23 +0200, Laszlo Ersek wrote:
>>>>>>>> Oh and I think both this patch and the assembly language
>>>>>>>> implementation for the atomics should be delayed after the stable
>>>>>>>> tag. gcc-10 is a new toolchain; so even if we don't introduce a
>>>>>>>> new toolchain tag such as
>>>>>>>> GCC10 for it, whatever we do in order to make it work, that's
>>>>>>>> feature enablement in my book.
>>>>>>>
>>>>>>> Works for me. By the time the next stable tag comes around, early
>>>>>>> adopters that are now on GCC 10.1 will likely have moved to 10.2 by
>>>>>>> that time, and so we may not need the assembly patch at all.
>>>>>>
>>>>>> I'm not ecstatic that we'll be releasing the first stable tag known
>>>>>> to break with current toolchains.
>>>>>
>>>>> If this breakage affects "current toolchains", then why was
>>>>> <https://bugzilla.tianocore.org/show_bug.cgi?id=2723> only reported
>>>>> on 2020-May-19, four days into the soft feature freeze?
>>>>
>>>> I agree the timing is crap.
>>>>
>>>>>> This isn't just affecting random crazies pulling latest toolchains
>>>>>> down, but people using their distro defaults (native or cross).
>>>>>
>>>>> ... "people using their distro defaults" to *not* build upstream edk2
>>>>> until 2020-May-19, apparently.
>>>>
>>>> Or distro defaults changing in between. I mean, we could say "Arch is
>>>> the same as any other distro's unstable", but I wouldn't want to go
>>>> down that route - I know people who use it for developing also for
>>>> qemu and linux.
>>>>
>>>> Argh, I also just realised the error report I saw two days after Ard's
>>>> intrinsics patch hit the list was not a public report. Yes, if this
>>>> had affected only in-development/unstable distributions, I agree this
>>>> isn't something we should try to deal with upstream.
>>>>
>>>>>> I don't recall if 10.1 ended up being default in F32, but it was
>>>>>> definitely included. In Arch, it does appear default.
>>>>>>
>>>>>> Debian/Ubuntu are unaffected in their stable releases.
>>>>>>
>>>>>> I agree it's a transitional issue, but I would really prefer to have
>>>>>> the intrinsics included in the release.
>>>>>
>>>>> OK, let's delay the release then, by a few days. I agree the present
>>>>> patch may qualify as a bugfix, but the other patch with the assembly
>>>>> language intrinsics doesn't. If it's really that important to have in
>>>>> the upcoming stable tag, then it's worth delaying the tag for. I'm
>>>>> fine delaying the release for it; it wouldn't be without precedent.
>>>>
>>>> I would argue it *is* a bugfix, since it only has an effect on builds
>>>> that would otherwise fail.
>>>
>>> OK. That's a good argument. From my POV, feel free to merge (both patches).
>>>
>>> Thanks
>>> Laszlo
>>>
>>>> But I also do think it is important enough to delay the release if we
>>>> feel that is necessary.
>>>>
>>>> /
>>>>       Leif
>>>>
>>>>> Also, I think Ard's assembly language patch needs a Tested-by from
>>>>> Gary at the least (reporter of TianoCore#2723). Please reach out to
>>>>> him in that thread.
>>>>>
>>>>> ... More precisely, please *ping* Gary for a Tested-by in that
>>>>> thread, because Ard CC'd him from the start, and even credited Gary
>>>>> in the commit message.
>>>>>
>>>>> Thanks,
>>>>> Laszlo
>>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>> 
>