linux-kernel - Re: [PATCH 3/3] resource: Introduce resource cache

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Message-ID: <8736k49c57.fsf@firstfloor.org>
Date:   Thu, 20 Jun 2019 14:31:48 -0700
From:   Andi Kleen <andi@...stfloor.org>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>, Nadav Amit <namit@...are.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>, Borislav Petkov <bp@...e.de>,
        Toshi Kani <toshi.kani@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...nel.org>,
        "Kleen\, Andi" <andi.kleen@...el.com>
Subject: Re: [PATCH 3/3] resource: Introduce resource cache

Dan Williams <dan.j.williams@...el.com> writes:
>
> The underlying issue is that the x86-PAT implementation wants to
> ensure that conflicting mappings are not set up for the same physical
> address. This is mentioned in the developer manuals as problematic on
> some cpus. Andi, is lookup_memtype() and track_pfn_insert() still
> relevant?

There have been discussions about it in the past, and the right answer
will likely differ for different CPUs: But so far the official answer
for Intel CPUs is that these caching conflicts should be avoided.

So I guess the cache in the original email makes sense for now.

-Andi