linux-kernel - Re: [RESEND v13 11/25] cxl/pci: Log message if RAS registers are unmapped

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Message-ID: <691d3913781e8_1a3751009b@dwillia2-mobl4.notmuch>
Date: Tue, 18 Nov 2025 19:27:15 -0800
From: <dan.j.williams@...el.com>
To: Terry Bowman <terry.bowman@....com>, <dave@...olabs.net>,
	<jonathan.cameron@...wei.com>, <dave.jiang@...el.com>,
	<alison.schofield@...el.com>, <dan.j.williams@...el.com>,
	<bhelgaas@...gle.com>, <shiju.jose@...wei.com>, <ming.li@...omail.com>,
	<Smita.KoralahalliChannabasappa@....com>, <rrichter@....com>,
	<dan.carpenter@...aro.org>, <PradeepVineshReddy.Kodamati@....com>,
	<lukas@...ner.de>, <Benjamin.Cheatham@....com>,
	<sathyanarayanan.kuppuswamy@...ux.intel.com>, <linux-cxl@...r.kernel.org>,
	<alucerop@....com>, <ira.weiny@...el.com>
CC: <linux-kernel@...r.kernel.org>, <linux-pci@...r.kernel.org>,
	<terry.bowman@....com>
Subject: Re: [RESEND v13 11/25] cxl/pci: Log message if RAS registers are
 unmapped

Terry Bowman wrote:
> The CXL RAS handlers do not currently log if the RAS registers are
> unmapped. This is needed in order to help debug CXL error handling. Update
> the CXL driver to log a warning message if the RAS register block is
> unmapped during RAS error handling.

That does not tell me anything about why this patch is needed, how this
scenario is entered and why catching this late is ok.

I do not have a problem with the change:

Reviewed-by: Dan Williams <dan.j.williams@...el.com>

...but I would steer away from patches that just say "add debug, because
debug helps debug".

What is more interesting is a story like:

"I lost a bunch of time figuring out why error handling was not working
only to find that in $scenario the RAS registers are not mapped. Save
the next person time by logging this condition".

Otherwise, if I NAK this patch I have no sense that Linux is any worse
off, and fewer patches is a virtue worth considering.