linux-kernel - Re: [PATCH] ACPI/PPTT: Handle architecturally unknown cache types

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Message-ID: <f553018d-d27a-68e0-93f7-4f7a0497c68a@arm.com>
Date:   Wed, 12 Sep 2018 10:39:34 -0500
From:   Jeremy Linton <jeremy.linton@....com>
To:     Jeffrey Hugo <jhugo@...eaurora.org>, rjw@...ysocki.net,
        linux-acpi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, vkilari@...eaurora.org,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH] ACPI/PPTT: Handle architecturally unknown cache types

Hi,


On 09/12/2018 09:41 AM, Jeffrey Hugo wrote:
> The HW designers have indicated that there is no sane way to provide 
> sets/ways information to software, even on an informational basis (ie 
> not for cache maintenance, but for performance optimizations). Therefore 
> the firmware will not provide this information because it will be wrong.
> 
> So, therefore, we should still be able to tell the user that a cache 
> exists at the relevant level, and what size it is.  On the concerned 
> system, we cannot do that currently.

Ok, so set the fields to zero in firmware node, and mark them valid.

That logically says that there isn't any set/way information for the 
cache (which implies direct mapped).