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Date: Fri, 20 Jun 2014 11:57:21 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Borislav Petkov <bp@alien8.de>
CC: Dave Hansen <dave@sr71.net>, linux-kernel@vger.kernel.org, x86@kernel.org,
        Andi Kleen <ak@linux.intel.com>
Subject: Re: [RFC][PATCH 3/3] x86: make MP  a required-feature on 64-bit
References: <20140620161736.D6AC16FD@viggo.jf.intel.com> <20140620161740.BFB00798@viggo.jf.intel.com> <53A46008.5060509@zytor.com> <53A4619C.8020100@sr71.net> <53A46365.6090101@zytor.com> <20140620174345.GD11391@pd.tnic> <53A47461.4050409@zytor.com> <20140620181518.GG11391@pd.tnic>
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On 06/20/2014 11:15 AM, Borislav Petkov wrote:
> On Fri, Jun 20, 2014 at 10:50:25AM -0700, H. Peter Anvin wrote:
>> Looking at the AMD init code, there is a whole bunch of other 32/64-bit
>> differences that are clearly bogus.  I also see that amd_k7_smp_check()
>> doesn't even *exist* on 64 bits, and that init_amd_k7() which calls
>> amd_k7_smp_check() only is ever called for family == 6, despite having
>> tests for family 7 and above in it.
> 
> No, K7 is family 6. The tests are for c->x86_model, or am I looking at
> the wrong place?
> 
> OTOH, init_amd() could probably use a cleanup of moving the per-family
> code into init_amd_<fam>() functions and extending the switch-case.
> 
> I'll take a look.
> 

Ah, yes, you're right.

This code is clearly not applicable to any 64-bit CPU, so cpu_has_mp is
simply a noop on 64 bits... so no need for Dave H. to worry about it at
all; we should get rid of it and replace it with cpu_has() in the AMD code.

I actually have Linus' old dual-processor K7 sitting in my garage, but
$DEITY knows if it actually runs.

	-hpa

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