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From: Andy Lutomirski <luto@amacapital.net>
Date: Thu, 9 Mar 2017 10:14:02 -0800
Message-ID: <CALCETrW+BvitFwre7uMFwOU6AWoTYK6qOcGCYm09hGDMrBxyJg@mail.gmail.com>
Subject: Re: [PATCH] x86/dmi: Switch dmi_remap to ioremap_cache
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: Julian Brost <julian.brost@fau.de>, Andy Lutomirski <luto@kernel.org>,
        Jean Delvare <jdelvare@suse.de>, X86 ML <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
        Denys Vlasenko <dvlasenk@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Luis R. Rodriguez" <mcgrof@suse.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>, Toshi Kani <toshi.kani@hp.com>,
        Ingo Molnar <mingo@kernel.org>, problems@cip.cs.fau.de
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On Thu, Mar 9, 2017 at 9:51 AM, Arjan van de Ven <arjan@linux.intel.com> wrote:
> On 3/9/2017 9:48 AM, Julian Brost wrote:
>
>> I'm note entirely sure whether it's actually the kernel or HP to blame,
>> but for now, hp-health is completely broken on 4.9 (probably on
>> everything starting from 4.6), so this patch should be reviewed again.
>
>
> it looks like another kernel driver is doing a conflicting mapping.
> do these HP tools come with their own kernel drivers or are those in the
> upstream kernel nowadays?
>

I assume that the kernel DMI driver itself is now a conflicting
mapping.  I wonder if it could register some kind of resource so that
/dev/mem knows to just map it writeback.

On the other hand, the right answer is to use /sys/firmware/dmi.  I'm
not sure the kernel ABI stability guarantee applies to /dev/mem.

--Andy