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From: "Winiarska, Iwona" <iwona.winiarska@intel.com>
To: "bp@alien8.de" <bp@alien8.de>
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Subject: Re: [PATCH v2 01/15] x86/cpu: Move intel-family to arch-independent headers
Date: Tue, 12 Oct 2021 23:15:00 +0000	[thread overview]
Message-ID: <15d81463b631e03b00a7031510304d5598fc246c.camel@intel.com> (raw)
In-Reply-To: <YWStQSrRJQ09KXVY@zn.tnic>

On Mon, 2021-10-11 at 23:31 +0200, Borislav Petkov wrote:
> On Mon, Oct 11, 2021 at 08:38:43PM +0000, Winiarska, Iwona wrote:
> > Everything that's part of this series runs on the BMC (Baseboard
> > Management Controller). There's nothing ARM specific to it - it's just
> > that the BMC hardware we're currently supporting is ARM-based. PECI is
> > an interface that's exposed by some x86 CPUs - but that's a hardware
> > interface (available completely independent from whatever is actually
> > running on the x86 CPU).
> 
> Aha, I think I got it: so this whole PECI pile is supposed to run on
> the BMC - which can be ARM but doesn't have to be, i.e., code should be
> generic enough - and the interfaces to the x86 CPU do get exposed to the
> Linux running on the BMC.
> 
> Which brings me to the answer to your other mail:
> 
> On Mon, Oct 11, 2021 at 07:32:38PM +0000, Winiarska, Iwona wrote:
> > Nothing wrong - just a trade-off between churn and keeping things tidy
> > and not duplicated, similar to patch 1. And just like in patch 1, if
> > you have a strong opinion against it - we can duplicate.
> 
> So it is not about strong opinion. Rather, it is about whether this
> exporting would be disadvantageous for x86 freedom. And I think it will
> be:
> 
> Because if you exported those and then we went and changed those
> interfaces and defines (changed their naming, function arguments,
> whatever) and something outside of x86 used them, we will break that
> something.
> 
> And usually we go and fix those users too but I doubt anyone has access
> to that PECI hw to actually test fixes, etc, etc.

We (OpenBMC) do have PECI HW, so that shouldn't be a problem.

> So I'd prefer the small amount of duplication vs external stuff using
> x86 facilities any day of the week. And so I'd suggest you simply copy
> the handful of functions and defines you're gonna be needing and the
> defines and be done with it.
> 
> Dave's idea makes sense to me too but lately it keeps happening that
> we change something in x86-land and it turns out something "from the
> outside" is using it and it breaks, so it is a lot easier if things are
> independent.

Both CPUID.EAX=1 decoding and definitions in intel-family are pretty "well-
defined". I understand the scenario that you're describing, but in order to
break the outside user there would need to be some "logic" behind the pulled in
concepts (if, for example, I would use something like X86_MATCH_* defines in
PECI).

Thanks
-Iwona

> 
> Thx.
> 


  reply	other threads:[~2021-10-13 21:22 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-03 11:31 [PATCH v2 00/15] Introduce PECI subsystem Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 01/15] x86/cpu: Move intel-family to arch-independent headers Iwona Winiarska
2021-10-04 19:03   ` Borislav Petkov
2021-10-11 19:21     ` Winiarska, Iwona
2021-10-11 19:40       ` Dave Hansen
2021-10-11 20:53         ` Winiarska, Iwona
2021-10-11 23:12           ` Dave Hansen
2021-10-11 20:06       ` Borislav Petkov
2021-10-11 20:38         ` Winiarska, Iwona
2021-10-11 21:31           ` Borislav Petkov
2021-10-12 23:15             ` Winiarska, Iwona [this message]
2021-10-13  6:42               ` Borislav Petkov
2021-08-03 11:31 ` [PATCH v2 02/15] x86/cpu: Extract cpuid helpers to arch-independent Iwona Winiarska
2021-10-04 19:08   ` Borislav Petkov
2021-10-11 19:32     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 03/15] dt-bindings: Add generic bindings for PECI Iwona Winiarska
2021-08-11 18:11   ` Rob Herring
2021-08-03 11:31 ` [PATCH v2 04/15] dt-bindings: Add bindings for peci-aspeed Iwona Winiarska
2021-08-11 18:11   ` Rob Herring
2021-08-03 11:31 ` [PATCH v2 05/15] ARM: dts: aspeed: Add PECI controller nodes Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 06/15] peci: Add core infrastructure Iwona Winiarska
2021-08-25 22:58   ` Dan Williams
2021-08-26 22:40     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 07/15] peci: Add peci-aspeed controller driver Iwona Winiarska
2021-08-26  1:35   ` Dan Williams
2021-08-26 23:54     ` Winiarska, Iwona
2021-08-27 16:24       ` Dan Williams
2021-08-29 19:42         ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 08/15] peci: Add device detection Iwona Winiarska
2021-08-27 19:01   ` Dan Williams
2021-11-15 22:18     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 09/15] peci: Add sysfs interface for PECI bus Iwona Winiarska
2021-08-27 19:11   ` Dan Williams
2021-11-15 22:19     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 10/15] peci: Add support for PECI device drivers Iwona Winiarska
2021-08-27 21:19   ` Dan Williams
2021-11-15 22:20     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 11/15] peci: Add peci-cpu driver Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 12/15] hwmon: peci: Add cputemp driver Iwona Winiarska
2021-08-03 15:24   ` Guenter Roeck
2021-08-04 10:43     ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 13/15] hwmon: peci: Add dimmtemp driver Iwona Winiarska
2021-08-03 15:39   ` Guenter Roeck
2021-08-04 10:46     ` Winiarska, Iwona
2021-08-04 17:33       ` Guenter Roeck
2021-08-05 21:48         ` Winiarska, Iwona
2021-08-03 11:31 ` [PATCH v2 14/15] docs: hwmon: Document PECI drivers Iwona Winiarska
2021-08-03 11:31 ` [PATCH v2 15/15] docs: Add PECI documentation Iwona Winiarska
2021-08-05 12:17 ` [PATCH v2 00/15] Introduce PECI subsystem Greg Kroah-Hartman

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