linux-kernel - Re: [PATCH v8 00/10] misc: Move AMD side band interface(SBI) functionality

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Message-Id: <06b76e0f-0b47-47ea-a48f-2bf09ac4a62c@app.fastmail.com>
Date: Fri, 11 Apr 2025 15:51:55 +0200
From: "Arnd Bergmann" <arnd@...db.de>
To: "Akshay Gupta" <akshay.gupta@....com>, linux-hwmon@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: "Guenter Roeck" <linux@...ck-us.net>,
 "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>, shyam-sundar.s-k@....com,
 gautham.shenoy@....com, "Mario Limonciello" <mario.limonciello@....com>,
 naveenkrishna.chatradhi@....com, anand.umarji@....com
Subject: Re: [PATCH v8 00/10] misc: Move AMD side band interface(SBI) functionality

On Fri, Apr 11, 2025, at 15:31, Akshay Gupta wrote:
> At present, sbrmi driver under hwmon subsystem, is probed as an i2c 
> driver,
> fetches data using APML specified protocol and reports through hwmon 
> power sensor.
>
> AMD provides additional information using custom protocols, which cannot be
> enumerated as hwmon sensors. Hence, move the existing functionality from hwmon/
> to misc/ and add support for following custom protocols
>   - read Processor feature capabilities and configuration information
>     through side band.
>   - read Machine Check Architecture(MCA) registers over sideband.
>     The information is accessed for range of MCA registers by passing
>     register address and thread ID to the protocol.
>
> NOTE: AMD defines Advanced Platform Management Link (APML) interface 
> which provides
> system management functionality access to the baseboard management
> controller (BMC).

I think this addresses all my comments, thanks for the update.

> Open-sourced and widely used [1]_ will continue to provide user-space 
> programmable API.
>
> .. [1] https://github.com/amd/esmi_oob_library

I'm still a little uneasy about the low-level mailbox interface
being exposed in a character device, but assuming that everyone
else is fine with having that in principle, I think the way the
interface is structured in this version is good enough.

     Arnd