From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zg8tmja5ljk3lje4ms43mwaa.icoremail.net (zg8tmja5ljk3lje4ms43mwaa.icoremail.net [209.97.181.73]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4558B303A12; Mon, 26 Jan 2026 09:07:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.97.181.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769418441; cv=none; b=L7iWd6/OLV6F6ygIdp4rSTdthZt+zkLq9L/q24JyJ/PbhAzprfa/toq7QcjOy8leJQlOy+7j7OexO35g2rG1/NzIB0/cSpEeK0hK3oQ38s1uSJZ3y0eYm6oLBFCdW6D9TCMhcP4M/waMku6ZdpC6pznVXnDe3XSzCzt8mwYgeDw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769418441; c=relaxed/simple; bh=4eQrDZNXV5sLSJhe9LmmKIBEtk5Mr8s64c1XKPFNqKM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kjlkawrJIlPKJ5hBCELWrIx181C020bBa3ViCOV/zlDq9dwKO3aW5qxl4MJLr4zGxgLlu2wMIJBrx2c2CnEFlilPBpyqiCN6nFkWxzEg9dzP9H/JuT3U6PnEYti6zeliLRP8kfv85F0Tnh+YuVrl9BLZO+CHL1BTbVcTZT6RLak= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=phytium.com.cn; spf=pass smtp.mailfrom=phytium.com.cn; arc=none smtp.client-ip=209.97.181.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=phytium.com.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=phytium.com.cn Received: from prodtpl.icoremail.net (unknown [10.12.1.20]) by hzbj-icmmx-6 (Coremail) with SMTP id AQAAfwD3A12tLndp7GBmAw--.30612S2; Mon, 26 Jan 2026 17:06:53 +0800 (CST) Received: from [10.22.77.56] (unknown [123.150.8.50]) by mail (Coremail) with SMTP id AQAAfwAHX+yrLndpaKIWAA--.39254S2; Mon, 26 Jan 2026 17:06:52 +0800 (CST) Message-ID: Date: Mon, 26 Jan 2026 17:06:52 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/1] mm: numa_memblks: Identify the accurate NUMA ID of CFMW To: Gregory Price Cc: dan.j.williams@intel.com, Andrew Morton , Jonathan Cameron , Mike Rapoport , Wang Yinfeng , linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260106031042.1606729-1-cuichao1753@phytium.com.cn> <20260106031042.1606729-2-cuichao1753@phytium.com.cn> <20260108094812.8757ce3ad8370668eaafb29c@linux-foundation.org> <9132054c-3017-4af0-84e0-e4359b0794a6@phytium.com.cn> <20260115101858.85fd7b8e837c1c92a4fdc5f0@linux-foundation.org> <696944eca1837_34d2a10056@dwillia2-mobl4.notmuch> <2d1e23ad-7ec1-483b-88b3-70ce19b69106@phytium.com.cn> From: Cui Chao In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:AQAAfwAHX+yrLndpaKIWAA--.39254S2 X-CM-SenderInfo: pfxlux1drrlkut6sx5pwlxzhxfrphubq/1tbiAQAHAGl2eO0EOAAAsw Authentication-Results: hzbj-icmmx-6; spf=neutral smtp.mail=cuichao175 3@phytium.com.cn; X-Coremail-Antispam: 1Uk129KBjvJXoW7WF1DKrWUXr4rXF13CF48JFb_yoW8Zw48pa yrKrZYyFnrKFyS9wn29w4DWr15ZFs5CayUCryUuFyxZF4q9F1ftr48tan09a9rJr1xC3W0 qFsFqr93uF95Z3JanT9S1TB71UUUUj7qnTZGkaVYY2UrUUUUj1kv1TuYvTs0mT0YCTnIWj DUYxn0WfASr-VFAU7a7-sFnT9fnUUIcSsGvfJ3UbIYCTnIWIevJa73UjIFyTuYvj4RJUUU UUUUU On 1/24/2026 12:46 AM, Gregory Price wrote: > On Thu, Jan 22, 2026 at 04:03:49PM +0800, Cui Chao wrote: >> 2.Why a Kernel Update is Recommended Over a Firmware Update: >> >> In the scenario of dynamic CXL region creation, the association between the >> memory's HPA range and its corresponding NUMA node is established when the >> kernel driver performs the commit operation. This is a runtime, OS-managed >> operation where the platform firmware cannot intervene to provide a fix. >> > This is not accurate > > The memory-to-node association for CXL memory is built by acpi logic: > > linux/drivers/acpi/numa/srat.c > > Specifically: > > acpi_parse_memory_affinity() /* if SRAT entry exists */ > -> numa_add_memblk(node, start, end) > > acpi_parse_cfmws() /* if no SRAT entry exists */ > -> numa_add_reserved_memblk(node, start, end) > > > This patch implies the latter is occurring - as it queries the reserved > block associations - meaning your platform is not shipping SRAT tables > for CXL memory regions. Sorry，my previous statement was ambiguous. What I intended to convey is that the moment when CXL memory is actually assigned to a dedicated NUMA node and becomes ready for use by applications is precisely during the creation of the region. > We have only seen this in QEMU - and this is correctable in firmware. > > But if this is shipped hardware, letting us know the platform lets us > know whether we should backport it. > > --- > > All that said, this does look harmless, and seems reasonable - but the > changelog should reflect what the hardware is doing above. This issue was discovered on the QEMU platform. I need to apologize for my earlier imprecise statement (claiming it was hardware instead of QEMU). My core point at the time was to emphasize that this is a problem in the general code path when facing this scenario, not a QEMU-specific emulation issue, and therefore it could theoretically affect real hardware as well. I apologize for any confusion this may have caused. > > ~Gregory -- Best regards, Cui Chao.