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[209.51.188.17]) by mx.google.com with ESMTPS id u7-20020a05620a0c4700b0076ce7b71d9fsi8301955qki.586.2023.08.24.02.07.12 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 24 Aug 2023 02:07:12 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; spf=pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nongnu.org Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qZ6Iv-00038i-TQ; Thu, 24 Aug 2023 05:07:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qZ6Iv-00038B-0g for qemu-arm@nongnu.org; Thu, 24 Aug 2023 05:07:01 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qZ6Iq-0007EO-2Y for qemu-arm@nongnu.org; Thu, 24 Aug 2023 05:07:00 -0400 Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4RWccv6YVpz6D8cD; Thu, 24 Aug 2023 17:05:51 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 24 Aug 2023 10:06:36 +0100 Date: Thu, 24 Aug 2023 10:06:35 +0100 To: Gregory Price CC: Yuquan Wang , qemu-arm Subject: Re: CXL Namespaces of ACPI disappearing in Qemu demo Message-ID: <20230824100635.0000565d@Huawei.com> In-Reply-To: References: <2023082215220191352877@phytium.com.cn> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100004.china.huawei.com (7.191.162.219) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=185.176.79.56; envelope-from=jonathan.cameron@huawei.com; helo=frasgout.his.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-arm@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-to: Jonathan Cameron From: Jonathan Cameron via Errors-To: qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org Sender: qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org X-TUID: n5o/8oeIxIVy On Wed, 23 Aug 2023 15:44:35 -0400 Gregory Price wrote: > On Tue, Aug 22, 2023 at 03:22:02PM +0800, Yuquan Wang wrote: > > Hi, Gregory > > I am sorry to disturb you, but there was still an ignored problem about= CXL,=20 > > Although I had sent an email to jonathan (maybe he is busy recently so = he forgot to reply), =20 > > the Link is : https://lists.nongnu.org/archive/html/qemu-arm/2023-08/ms= g00278.html=20 > >=20 > > Maybe the core question is that how should we use CXL components with a= standard PCIe system=EF=BC=9A > > 1) In Qemu, since the boards or machines in qemu can only use pxb-cxl (= attached on pcie.0) to add > > cxl host bridge, therefore, users should avoid to assign an occupied bu= s number by other devices > > to pxb-cxl. > >=20 > > 2) In real hardware, CXL components should use independent CXL root/tre= e (ACPI0017&ACPI0016) > > to separate from the namespace of default pcie root/domain. > >=20 > > I would be grateful if you have some free time to help check this issue= : ) > > =20 >=20 > Generally speaking, ACPI questions are outside the scope of my > knowledge, but to the extent that i have debugged QEMU for CXL I can say > that #1 is correct - the host bridge adapter should not share PCI bus > id's with anything else or you will have issues. This can be > frustrating if you don't know what the magic numbers are. >=20 > for my work, i have been using this when i need to attach two pxb-cxl > deivces >=20 > qemu-system-x86_64 \ > -drive file=3D./cxl.qcow2,format=3Dqcow2,index=3D0,media=3Ddisk,id=3Dhd \ > -m 4G,slots=3D4,maxmem=3D8G \ > -smp 4 \ > -machine type=3Dq35,cxl=3Don,hmat=3Don \ > -device pxb-cxl,id=3Dcxl.0,bus=3Dpcie.0,bus_nr=3D52 \ > -device pxb-cxl,id=3Dcxl.1,bus=3Dpcie.0,bus_nr=3D191 \ >=20 >=20 > In regards to real hardware, I'm honestly not knowledgable enough about > ACPI or hardware to provide an intelligible answer unfortunately. >=20 > ~Gregory One additional thing to note. Nothing stops you putting a PCI device on a C= XL root port, or downstream switch port. Some of the reporting is probably wr= ong at the moment, but I've messed around with NVME below one and that 'works' = fine as Linux doesn't read the relevant registers anyway. Jonathan