Re: [edk2-devel] [PATCH v2] ArmPkg/CompilerIntrinsicsLib: provide atomics intrinsics

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

On 5/21/20 1:23 PM, Leif Lindholm via groups.io wrote:
> On Wed, May 20, 2020 at 13:44:48 +0200, Ard Biesheuvel wrote:
>> Gary reports the GCC 10 will emit calls to atomics intrinsics routines
>> unless -mno-outline-atomics is specified. This means GCC-10 introduces
>> new intrinsics, and even though it would be possible to work around this
>> by specifying the command line option, this would require a new GCC10
>> toolchain profile to be created, which we prefer to avoid.
>>
>> So instead, add the new intrinsics to our library so they are provided
>> when necessary.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
> 
> I feel unsure about whether this change is still proposed to go in,
> but if it is, please fold in a BZ reference
> (https://bugzilla.tianocore.org/show_bug.cgi?id=2723) in commit
> message. With that:
> 
> Reviewed-by: Leif Lindholm <leif@nuviainc.com>
> Thanks!
> 

Apparently, GCC 10 is getting fixed so that we can set a #pragma in 
MdePkg/Include/AArch64/ProcessorBind.h, and be done with it.

That does mean you would need GCC 10.2 at least, or you get the error, 
unless we merge this patch as well. That would mean the intrinsics are 
never used in practice, but using a compiler that does use them will not 
break the build.

I am leaning towards omitting this patch, but I could be convinced to 
adopt both mitigations. But the #pragma is strongly preferred.