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Date: Tue, 08 Jan 2013 15:17:46 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Borislav Petkov <bp@alien8.de>,
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        "Eric W. Biederman" <ebiederm@xmission.com>,
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Subject: Re: [PATCH v7 00/27] x86, boot, 64bit: Add support for loading ramdisk
 and bzImage above 4G
References: <1355814959-10573-1-git-send-email-yinghai@kernel.org> <20121222024225.GG3468@phenom.dumpdata.com> <eee81bb9-f11b-4ff8-8a84-72f122766fd8@email.android.com> <20121222132419.GB2936@phenom.dumpdata.com> <50D8FBF9.6050509@zytor.com> <20121225115226.GD7720@liondog.tnic> <e91771a5-0d4e-457b-a3da-f8e855a1baa0@email.android.com> <20130108210840.GC23616@liondog.tnic> <48eb20be-0b49-43f9-ba73-7ab6849f2bf1@email.android.com> <20130108211931.GD23616@liondog.tnic>
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On 01/08/2013 01:19 PM, Borislav Petkov wrote:
> On Tue, Jan 08, 2013 at 01:15:41PM -0800, H. Peter Anvin wrote:
>> Yes, but why bother...
>
> I suspected something like that to be the reason after reading into that
> section of the APM of how one needs to jump through hoops to do one
> lousy far jump.
>

The only thing that started this was that I got tempted into a 
microoptimization that happens to be valid and documented on Intel, but 
not AMD.  Given that it doesn't actually work lretq is probably the 
least insane option.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.