Message-ID: <4DDC3A1A.6030006@zytor.com>
Date: Tue, 24 May 2011 16:07:06 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Dan Rosenberg <drosenberg@vsecurity.com>
CC: Tony Luck <tony.luck@gmail.com>, linux-kernel@vger.kernel.org,
        davej@redhat.com, kees.cook@canonical.com, davem@davemloft.net,
        eranian@google.com, torvalds@linux-foundation.org, adobriyan@gmail.com,
        penberg@kernel.org, Arjan van de Ven <arjan@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>, Valdis.Kletnieks@vt.edu,
        Ingo Molnar <mingo@elte.hu>, pageexec@freemail.hu
Subject: Re: [RFC][PATCH] Randomize kernel base address on boot
References: <1306269105.21443.20.camel@dan>  <4DDC31DF.5010303@zytor.com> <1306278296.1921.10.camel@dan>
In-Reply-To: <1306278296.1921.10.camel@dan>
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On 05/24/2011 04:04 PM, Dan Rosenberg wrote:
> 
>> 2. Not introduce a performance regression (we avoid locating in the
>>    bottom 16 MiB for performance reasons, except on very small systems);
> 
> I altered the boot code so that it uses CONFIG_PHYSICAL_START, which
> defaults to 16 MiB, as a lower bound on location.  So nothing will ever
> get loaded below there, and I still can take advantage of higher
> alignment granularity.  Are there other problems I'm not anticipating?
> 

Please look at the discussion as to what led us to do things this way.

	-hpa
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