linux-kernel - Re: [PATCH v4 06/13] x86/platform/uv: Add and Decode Arch Type in UVsystab

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Message-ID: <ee51449f-22b1-1074-19c1-b1b5a51fed64@hpe.com>
Date:   Tue, 6 Oct 2020 18:21:14 -0700
From:   Mike Travis <mike.travis@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Steve Wahl <steve.wahl@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kernel test robot <lkp@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Russ Anderson <russ.anderson@....com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Jian Cai <caij2003@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v4 06/13] x86/platform/uv: Add and Decode Arch Type in
 UVsystab



On 10/6/2020 8:19 AM, Borislav Petkov wrote:
> On Mon, Oct 05, 2020 at 02:35:58PM -0700, Mike Travis wrote:
>>
>>
>> On 10/5/2020 2:21 PM, Borislav Petkov wrote:
>>> On Mon, Oct 05, 2020 at 03:39:22PM -0500, Mike Travis wrote:
>>>> A patch to add and process the UV Arch Type field in the UVsystab passed
>>>> from UV BIOS to the kernel.
>>>
>>> What does that mean?
>>>
>>
>> There have been recent cases where OEM's want to use the OEM_ID in the ACPI
>> tables to brand their own product.  The UV BIOS used that field to tell the
>> Linux kernel which UV arch the running system is.  The Arch Type in the
>> UVsystab (also created by UV BIOS) now carries that field in systems that
>> support it.
> 
> I am unclear on the whole patch passing from UV BIOS to the kernel. Are
> you talking about a kernel patch here? If so, commit ID is? Or what kind
> of patch are you talking about?
> 

When the UV BIOS starts the kernel it passes the UVsystab info struct to 
the kernel which contains information elements more specific than ACPI, 
and generally pertinent only to the MMR's.  These are read only fields 
so information is passed one way only.  A new field starting with UV5 is 
the UV architecture type so the ACPI OEM_ID field can be used for other 
purposes going forward.  The UV Arch Type selects the entirety of the 
MMRs available, with their addresses and fields defined in uv_mmrs.h.

Thanks,
Mike