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

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Message-ID: <87ed2nsi4d.ffs@tglx>
Date: Wed, 04 Dec 2024 14:16:50 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Arnd Bergmann <arnd@...nel.org>, linux-kernel@...r.kernel.org,
 x86@...nel.org
Cc: Arnd Bergmann <arnd@...db.de>, Ingo Molnar <mingo@...hat.com>, Borislav
 Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, "H.
 Peter Anvin" <hpa@...or.com>, Linus Torvalds
 <torvalds@...ux-foundation.org>, Andy Shevchenko <andy@...nel.org>,
 Matthew Wilcox <willy@...radead.org>, Sean Christopherson
 <seanjc@...gle.com>, Davide Ciminaghi <ciminaghi@...dd.com>, Paolo Bonzini
 <pbonzini@...hat.com>, kvm@...r.kernel.org
Subject: Re: [PATCH 03/11] x86: Kconfig.cpu: split out 64-bit atom

On Wed, Dec 04 2024 at 11:30, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
>
> 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)...