Re: [PATCH 03/11] x86: Kconfig.cpu: split out 64-bit atom

[H. Peter Anvin]

On December 4, 2024 5:16:50 AM PST, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>On Wed, Dec 04 2024 at 11:30, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@xxxxxxxx>
>>
>> Both 32-bit and 64-bit builds allow optimizing using "-march=atom", but
>> this is somewhat suboptimal, as gcc and clang use this option to refer
>> to the original in-order "Bonnell" microarchitecture used in the early
>> "Diamondville" and "Silverthorne" processors that were mostly 32-bit only.
>>
>> The later 22nm "Silvermont" architecture saw a significant redesign to
>> an out-of-order architecture that is reflected in the -mtune=silvermont
>> flag in the compilers, and all of these are 64-bit capable.
>
>In theory. There are quite some crippled variants of silvermont which
>are 32-bit only (either fused or at least officially not-supported to
>run 64-bit)...
>

Yeah. That was a sad story, which I unfortunately am not at liberty to share.