linux-kernel - RE: [PATCH v2 3/3] ras/events: Trace CXL CPER events without CXL stack

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Date: Mon, 22 Apr 2024 17:16:07 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Ira Weiny <ira.weiny@...el.com>, Dave Jiang <dave.jiang@...el.com>, "Dan
 Williams" <dan.j.williams@...el.com>, Jonathan Cameron
	<jonathan.cameron@...wei.com>, Smita Koralahalli
	<Smita.KoralahalliChannabasappa@....com>, Shiju Jose <shiju.jose@...wei.com>
CC: Dan Carpenter <dan.carpenter@...aro.org>, Yazen Ghannam
	<yazen.ghannam@....com>, Davidlohr Bueso <dave@...olabs.net>, "Alison
 Schofield" <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ard Biesheuvel <ardb@...nel.org>,
	<linux-efi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-cxl@...r.kernel.org>, Ira Weiny <ira.weiny@...el.com>, "Rafael J.
 Wysocki" <rafael@...nel.org>, Tony Luck <tony.luck@...el.com>, "Borislav
 Petkov" <bp@...en8.de>
Subject: RE: [PATCH v2 3/3] ras/events: Trace CXL CPER events without CXL
 stack

Ira Weiny wrote:
> If CXL is solely managed by firmware (including HDM configuration and
> event processing via firmware first) it is possible to run the system
> without the CXL software loaded.  In this case no CXL callback will be
> loaded and CXL CPER errors will not be processed at all.
> 
> In this case memory device and region (HPA) information is missing but
> omitting the error completely is not friendly.  Some device information
> is available the event.
> 
> Trace CXL CPER events if the CXL stack is not loaded.  A balance was
> chosen to decode only the CPER header as this configuration is likely
> rare.

I think the justification for this is weak and it pollutes the user ABI.
What environment cares about CXL RAS without the CXL driver? If such a
use case ever pops up it is trivial to revive this otherwise saves
carrying this and all the minor maintenance overhead it causes.