From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 79CB07603F for ; Fri, 14 Mar 2025 17:04:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741971843; cv=none; b=MAYyfTGRLJihU5g6TAJ5lnkf3Pl86p8dYe9zGKia1BdqNbx++AhY3dK07RlpoueczpqXuqWM7xkfePPbrG9qrG/vHV9Sn9BYhylGylN5Ns4jYqc4QGkImvke/VDQ6v+MW5NHURQFHQvFvYSr2B2GaCiOhhLtpO9uMkYcvJEylZs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741971843; c=relaxed/simple; bh=k6gNDxg7YxBQVLpYwxNhnn2e4iGlCxD0WsNQw3LZFTM=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=a9N2PUy2/PYeHWaAqGGILbsdeLVcolvt+NmsXP9fbMsrxBvWG64PT6T9AN9n5nsXQnAgYBi02KWhBGHJIo0AmkuiHTHmTP8odynqMLRf3ao7BK7hzXEo5v/NhKo4JMM0S0aL3JjuSVNV17Vexx2KejALlFMld896XMIZ6XVFad0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4ZDrHK6F6Xz6JB7X; Sat, 15 Mar 2025 01:01:17 +0800 (CST) Received: from frapeml500008.china.huawei.com (unknown [7.182.85.71]) by mail.maildlp.com (Postfix) with ESMTPS id 340CE140D26; Sat, 15 Mar 2025 01:03:59 +0800 (CST) Received: from localhost (10.203.177.66) by frapeml500008.china.huawei.com (7.182.85.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Fri, 14 Mar 2025 18:03:58 +0100 Date: Fri, 14 Mar 2025 17:03:57 +0000 From: Jonathan Cameron To: Dan Williams CC: Yuquan Wang , , Subject: Re: [PATCH] docs/cxl: Add serial number for persistent-memdev Message-ID: <20250314170357.00000de3@huawei.com> In-Reply-To: <67d44ec5a79c1_12e31294ea@dwillia2-xfh.jf.intel.com.notmuch> References: <20250217112039.138650-1-wangyuquan1236@phytium.com.cn> <20250220161213.000049a9@huawei.com> <20250221065509-mutt-send-email-mst@kernel.org> <17b91a9f.2847.1955fd23d78.Coremail.wangyuquan1236@phytium.com.cn> <20250305141359.00001288@huawei.com> <4752672.2b5f.19565e01b65.Coremail.wangyuquan1236@phytium.com.cn> <20250312181035.00006e32@huawei.com> <67d44ec5a79c1_12e31294ea@dwillia2-xfh.jf.intel.com.notmuch> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: lhrpeml500003.china.huawei.com (7.191.162.67) To frapeml500008.china.huawei.com (7.182.85.71) On Fri, 14 Mar 2025 08:44:05 -0700 Dan Williams wrote: > Jonathan Cameron wrote: > > On Wed, 5 Mar 2025 18:35:40 +0800 > > Yuquan Wang wrote: > > =20 > > > >=20 > > > > On Tue, 4 Mar 2025 14:22:48 +0800 > > > > Yuquan Wang wrote: > > > > =20 > > > > > >=20 > > > > > > On Thu, Feb 20, 2025 at 04:12:13PM +0000, Jonathan Cameron wrot= e: =20 > > > > > > > On Mon, 17 Feb 2025 19:20:39 +0800 > > > > > > > Yuquan Wang wrote: > > > > > > > =20 > > > > > > > > Add serial number parameter in the cxl persistent examples. > > > > > > > >=20 > > > > > > > > Signed-off-by: Yuquan Wang = =20 > > > > > > > Looks good. I've queued it up on my gitlab staging tree, but > > > > > > > Michael if you want to pick this one directly that's fine as = well. =20 > > > > > >=20 > > > > > > See no reason to, I was not even CC'd. =20 > > > > >=20 > > > > > Hi, Michael > > > > >=20 > > > > > I'm sorry, this is my fault. I used "get_maintainer.pl" to check = this > > > > > patch's maintainers but it shows "No maintainers found, printing = recent > > > > > contributors".=20 > > > > > =20 > > > > I usually stage up multiple series together and send on to Michael. > > > > So it was be being lazy for a minor change rather than anything much > > > > that you did wrong. > > > >=20 > > > > If I get time I'll post a series with this a few other patches > > > > later today. =20 > > > >=20 > > > > Jonathan > > > > =20 > > > Thank you! > > >=20 > > > BTW, I found a corner case in CXL numa node creation. > > >=20 > > > Condition:=20 > > > 1) A UMA/NUMA system without SRAT, but with CEDT.CFMWS > > > 2=EF=BC=89Enable CONFIG_ACPI_NUMA > > >=20 > > > Results: > > > 1) acpi_numa_init: the fake_pxm will be 0 and send to acpi_parse_cfmw= s() > > > 2=EF=BC=89If dynamically create cxl ram region, the cxl memory would = be assigned > > > to node0 rather than a new node > > >=20 > > > Confusions: > > > 1) Is a numa system a requirement for CXL memory usage? =20 > >=20 > > Obviously discussion has gone on elsewhere, but I'd say in general it > > would be a bad idea to not have an SRAT because the moment we add CXL > > it is definitely a NUMA system and we want the Generic Port entry to > > allow us to get perf information. > >=20 > > So I wouldn't mind if we fail CXL init in this case, but maybe > > it is worth papering over things. =20 >=20 > I think that is too severe. If a driver has a path to advertise > resources, even in a less than ideal way, it should make every effort to > do that. There are plenty of ways for the NUMA information to fail, that > does not mean the memory needs to be prevented from coming online. Let > the end user decide if lack of performance information is fatal. You are too nice to those firmware folk ;) How will they learn! Everything in default node is fine. I don't much like the having broken normal numa setup combined with CXL trying to carry on with its node. I suspect that will be fragile in the long run. numa_off and other things set in that path tend to spread there wings into surprising places and broken / missing SRAT + CXL is something that isn't likely to get much testing. Jonathan >=20