linux-kernel - Re: [RFC PATCH 00/15] Prepare for new Intel family models

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Message-ID: <e2d01538-f2b7-4f0d-8688-124531530c59@intel.com>
Date: Mon, 23 Dec 2024 11:43:44 -0800
From: Sohil Mehta <sohil.mehta@...el.com>
To: Andrew Cooper <andrew.cooper3@...rix.com>
CC: <acme@...nel.org>, <adrian.hunter@...el.com>,
	<alexander.shishkin@...ux.intel.com>, <bp@...en8.de>,
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	<tony.luck@...el.com>, <viresh.kumar@...aro.org>, <x86@...nel.org>
Subject: Re: [RFC PATCH 00/15] Prepare for new Intel family models

On 12/20/2024 4:29 PM, Andrew Cooper wrote:
>>
>>   A dump of the microcode file 06-03-02 shows:
>>     001/001: sig 0x00001632, pf_mask 0x00, 1998-06-10, rev 0x0002, size 2048
>>   An archived CPUID dump [3] also says:
>>     CPUID 00000001: 00001632-00000000-00000000-0183FBFF
>>
>>   That would translate to a family number of 22 (0x16). This aberration is 
>>   not explicitly handled anywhere in the kernel so the platform might already 
>>   be broken. This series might make it worse for the platform if the latest 
>>   kernel works on it by chance.
> 
> Are you sure?  Bits 13:12 are the type field, and the 0x1 you've got is
> for an OverDrive processor.
> 

You are right. This is indeed the processor type field. I should have
spent more time reading the specification than Wikipedia :)


> x86_family() will consider this to be family 6 as far as I can see.
> 

On the bright side, we don't have to worry about breaking this CPU.

Sohil