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To: Arnd Bergmann <arnd@kernel.org>, linux-kernel@vger.kernel.org,
 x86@kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@redhat.com>, Borislav
 Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, "H.
 Peter Anvin" <hpa@zytor.com>, Linus Torvalds
 <torvalds@linux-foundation.org>, Andy Shevchenko <andy@kernel.org>,
 Matthew Wilcox <willy@infradead.org>, Sean Christopherson
 <seanjc@google.com>, Davide Ciminaghi <ciminaghi@gnudd.com>, Paolo Bonzini
 <pbonzini@redhat.com>, kvm@vger.kernel.org
Subject: Re: [PATCH 03/11] x86: Kconfig.cpu: split out 64-bit atom
In-Reply-To: <20241204103042.1904639-4-arnd@kernel.org>
References: <20241204103042.1904639-1-arnd@kernel.org>
 <20241204103042.1904639-4-arnd@kernel.org>
Date: Wed, 04 Dec 2024 14:16:50 +0100
Message-ID: <87ed2nsi4d.ffs@tglx>
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On Wed, Dec 04 2024 at 11:30, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.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)...