linux-kernel - Re: [PATCH] MAINTAINERS, x86/CPU: Tony Luck will maintain asm/intel-family.h

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Date:   Thu, 15 Aug 2019 11:30:55 -0700
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Dave Hansen <dave.hansen@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MAINTAINERS, x86/CPU: Tony Luck will maintain
 asm/intel-family.h

On Thu, Aug 15, 2019 at 07:54:55PM +0200, Borislav Petkov wrote:
> On Thu, Aug 15, 2019 at 10:21:59AM -0700, Luck, Tony wrote:
> > Like this?
> 
> Actually, I was thinking you'd put it above the defines in the file
> intel-family.h itself so that *everyone* who wants to add a model, sees
> it first and while that explanation below is very nice...

V2 ... ugh ... C doesn't do well with nested comments, so the example
has issues.  I chose to use a C++ style comment (as they are not as
verboten in Linux as they used to be).

Another option would be to put the instructions inside #if 0 ... #endif
but that seems less than ideal.

Any other ideas?

-Tony

>From 84624a3410a3ba03c3acb13e54b1292c3ca64b8c Mon Sep 17 00:00:00 2001
From: Tony Luck <tony.luck@...el.com>
Date: Thu, 15 Aug 2019 11:16:24 -0700
Subject: [PATCH] x86/cpu: Explain Intel model naming convention

Dave Hansen spelled out the rules in an e-mail:

 https://lkml.kernel.org/r/91eefbe4-e32b-d762-be4d-672ff915db47@intel.com

Copy those right into the <asm/intel-family.h> file to
make it easy for people to find them.

Suggested-by: Borislav Petkov <bp@...en8.de>
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/include/asm/intel-family.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/include/asm/intel-family.h b/arch/x86/include/asm/intel-family.h
index 0278aa66ef62..87443df77eee 100644
--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -11,6 +11,21 @@
  * While adding a new CPUID for a new microarchitecture, add a new
  * group to keep logically sorted out in chronological order. Within
  * that group keep the CPUID for the variants sorted by model number.
+ *
+ * HOWTO Build an INTEL_FAM6_ definition:
+ * 
+ * 1. Start with INTEL_FAM6_
+ * 2. If not Core-family, add a note about it, like "ATOM".  There are only
+ *    two options for this (Xeon Phi and Atom).  It is exceedingly unlikely
+ *    that you are adding a cpu which needs a new option here.
+ * 3. Add the processor microarchitecture, not the platform name
+ * 4. Add a short differentiator if necessary.  Add an _X to differentiate
+ *    Server from Client.
+ * 5. Add an optional comment with the platform name(s)
+ * 
+ * It should end up looking like this:
+ * 
+ * INTEL_FAM6_<ATOM?>_<MICROARCH>_<SHORT...> // Platform Name(s)
  */
 
 #define INTEL_FAM6_CORE_YONAH		0x0E
-- 
2.20.1