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

["Liming Gao" <liming.gao@intel.com>]

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. 
2) Can we think __GNUC_MINOR__ is always defined? Do we need to check its value after check whether it is defined or not?

Thanks
Liming
-----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
>>
>