Message-ID: <506B6191.6080605@zytor.com>
Date: Tue, 02 Oct 2012 14:50:09 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: T Makphaibulchoke <tmac@hp.com>
CC: tglx@linutronix.de, mingo@redhat.com, x86@kernel.org,
        akpm@linux-foundation.org, yinghai@kernel.org, tiwai@suse.de,
        viro@zeniv.linux.org.uk, aarcange@redhat.com, tony.luck@intel.com,
        mgorman@suse.de, weiyang@linux.vnet.ibm.com,
        octavian.purdila@intel.com, paul.gortmaker@windriver.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] Fix devmem_is_allowed for below 1MB accesses for an efi
 machine
References: <1349213536-3436-1-git-send-email-tmac@hp.com>
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On 10/02/2012 02:32 PM, T Makphaibulchoke wrote:
> Changing devmem_is_allowed so that on an EFI machine, access to physical
> address below 1 MB is allowed only to physical pages that are valid in
> the EFI memory map.  This prevents the possibility of an MCE due to
> accessing an invalid physical address.

What?

That sounds like exactly the opposite of normal /dev/mem behavior... we
allow access to non-memory resources (which really could do anything if
misused), but not memory.

You seem like you're flipping it on its head.

	-hpa

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