linux-kernel - Re: [PATCH v2] ACPI: PPTT: Dump PPTT table when error detected

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Message-ID: <CAJZ5v0gEXGo0c=5MB6fJftAHysvYZ5RUjRG53E2cH4GKF7SdqQ@mail.gmail.com>
Date: Wed, 14 Jan 2026 16:07:40 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Sudeep Holla <sudeep.holla@....com>
Cc: Feng Tang <feng.tang@...ux.alibaba.com>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Len Brown <lenb@...nel.org>, Jeremy Linton <jeremy.linton@....com>, 
	Hanjun Guo <guohanjun@...wei.com>, James Morse <james.morse@....com>, 
	Joanthan Cameron <Jonathan.Cameron@...wei.com>, linux-acpi@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ACPI: PPTT: Dump PPTT table when error detected

On Wed, Jan 14, 2026 at 4:06 PM Sudeep Holla <sudeep.holla@....com> wrote:
>
> On Wed, Jan 14, 2026 at 10:28:19PM +0800, Feng Tang wrote:
> >
> > As for the original issue where kernel printed the error message
> > " ACPI PPTT: PPTT table found, but unable to locate core 1 (1)",
> > can we just printed out all the CPU entries of the PPTT table?
> > which is much cleaner and smaller, and have the enough information
> > for quickly identifying the root cause. As the number of cache
> > items is usually 3X of number of CPUs.
>
> I am still not sure what additional value is gained by listing all those CPU
> entries. On a 512-CPU system, for example, if an issue is identified with the
> entry for CPU 256, what extra information is obtained by listing all the other
> CPUs, such as those sharing the same L3 cache or entire list of CPUs on this
> system?
>
> The message above already indicates that something is wrong with core
> (n = 1 in above case). If that is not sufficiently clear, it should be
> improved to be more specific about the issue. Simply listing all CPUs in the
> PPTT provides no additional insight and only results in an unnecessarily long
> and distracting CPU list in the kernel log.

Fair enough.