linux-kernel - Re: [RFC PATCH v3 0/2] ACPI: NUMA: debug invalid unused PXM value for CFMWs

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Message-ID: <67e48b81493c2_13cb2943c@dwillia2-mobl3.amr.corp.intel.com.notmuch>
Date: Wed, 26 Mar 2025 19:19:29 -0400
From: Dan Williams <dan.j.williams@...el.com>
To: Yuquan Wang <wangyuquan1236@...tium.com.cn>,
	<Jonathan.Cameron@...wei.com>, <dan.j.williams@...el.com>, <rppt@...nel.org>,
	<akpm@...ux-foundation.org>, <david@...hat.com>, <bfaccini@...dia.com>,
	<rafael@...nel.org>, <lenb@...nel.org>, <dave@...olabs.net>,
	<dave.jiang@...el.com>, <alison.schofield@...el.com>,
	<vishal.l.verma@...el.com>, <ira.weiny@...el.com>, <rrichter@....com>,
	<haibo1.xu@...el.com>
CC: <linux-acpi@...r.kernel.org>, <linux-cxl@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <chenbaozi@...tium.com.cn>, Yuquan Wang
	<wangyuquan1236@...tium.com.cn>
Subject: Re: [RFC PATCH v3 0/2] ACPI: NUMA: debug invalid unused PXM value
 for CFMWs

Yuquan Wang wrote:
> Changes in v3:
> - Introduce numa_add_reserved_memblk()
> - Use more explicit way to make sure CFMWs fake node >= 1 
> - Replace numa_add_memblk() with numa_add_reserved_memblk() in acpi_parse_cfmws()
> 
> Problem
> -------
> The absence of SRAT

Can you say more about CXL ACPI platforms that do not have an SRAT? That
seems like the first problem, and this information helps determine
whether this is a fix that needs backporting, or just a cleaner way to
handle this quirk.

> would cause the fake_pxm to be -1 and increment

Not an issue in your patch but it strikes me that "fake_pxm" is
misnamed. There is nothing "fake" about it. It is simply the first
synthesized CXL proximity domain for future CXL region provisioning.

I would not mind a separate patch renaming "fake_pxm" to "cxl_pxm", just
to not confuse future readers with the simulated nodes produced by
mm/numa_emulation.c.