linux-kernel - Re: [PATCH 0/9] Add CPU-type to topology

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Date: Thu, 20 Jun 2024 08:06:11 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Brice Goglin <brice.goglin@...il.com>,
 srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>,
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 x86@...nel.org, daniel.sneddon@...ux.intel.com, tony.luck@...el.com,
 linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
 linux-perf-users@...r.kernel.org, Josh Poimboeuf <jpoimboe@...nel.org>,
 "Rafael J. Wysocki" <rafael@...nel.org>,
 Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
 "Liang, Kan" <kan.liang@...ux.intel.com>,
 Andrew Cooper <andrew.cooper3@...rix.com>
Subject: Re: [PATCH 0/9] Add CPU-type to topology

On 6/19/24 14:25, Brice Goglin wrote:
> Good point. From this patch series, I understand that the current kernel
> side doesn't care about these different E-cores. However it might be
> good to expose them as different cpu-types (or better name) to userspace ?
> 
> Something like type 0 = P-core, 1 = normal E-core, 2 = low power E-core ?

The first priority here is getting the kernel to comprehend these types
for architectural purposes: when there are functional differences
between the cores.

Let's get that in place, first.  Then we can discuss the possibility of
new ABI in the area.

Did the ARM folks ever do a sysfs ABI for big.LITTLE?  I don't see
anything obvious in Documentation/ABI/testing/sysfs-devices-system-cpu.