From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C13B4C61DE2 for ; Sun, 30 Aug 2026 07:24:02 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x0ZtX-0003Be-5N; Sun, 30 Aug 2026 03:23:59 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x0ZtV-0003BT-Mv for qemu-devel@nongnu.org; Sun, 30 Aug 2026 03:23:57 -0400 Received: from mgamail.intel.com ([192.198.163.9]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x0ZtU-0005CD-9X for qemu-devel@nongnu.org; Sun, 30 Aug 2026 03:23:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1788074636; x=1819610636; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=aQ3/GtP+7FT0jHBto6tRWGX4KNJFHv61L74w2OzzTPo=; b=cDoCZwSXKvttXT7FFHF/twVCbRx8d51lyvstuHLDTLHhFZvtKRGJTrUl R1zk/8R5MzeDlxSoaiIKseKkM33OosQoeg34AL9fDjzR/oGiMHNjvynaL lR4c8+f/rTCRiIAsIX7fSVmkOu4LYrgpuTW6L76/HtQfARIEP1BmC9d4q JcrCBUsLfif/wiLNQeOpXCRW2dXd0D2CcX4YdU+sFxHlwTBD4okx9fP8o Nn1kocN2YJxYbzsbftXZHDnF/DziNHmRcQuokP+XUF4KkAnqN46+UbpVH tnioQjXWdUKSF6aOhbkKJvpgVwwt7OOy3qIct98qrqed6cwa+EtsEfB0A A==; X-CSE-ConnectionGUID: cbtfEVgEQWKXomRnEshEbQ== X-CSE-MsgGUID: TaE7+J9tQCOxeB0zuE2F2A== X-IronPort-AV: E=McAfee;i="6800,10657,11890"; a="99177855" X-IronPort-AV: E=Sophos;i="6.25,251,1779174000"; d="scan'208";a="99177855" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Aug 2026 00:23:54 -0700 X-CSE-ConnectionGUID: MX+8LuwiTAyCs4k/h1qcNg== X-CSE-MsgGUID: HKeYRdhESpmqIchBYOqe/A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,251,1779174000"; d="scan'208";a="270452285" Received: from junjie-desk-dev.bj.intel.com (HELO junjie-desk-dev.tail2c02c1.ts.net) ([10.238.152.71]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Aug 2026 00:23:51 -0700 From: Junjie Cao To: Shrihari E S Cc: jic23@kernel.org, fan.ni@samsung.com, mst@redhat.com, marcel.apfelbaum@gmail.com, dave@stgolabs.net, arun.george@samsung.com, dongjoo.seo1@samsung.com, s.neeraj@samsung.com, vikash.k5@samsung.com, cpgs@samsung.com, gost.dev@samsung.com, linux-cxl@vger.kernel.org, linux-pci@vger.kernel.org, qemu-devel@nongnu.org Subject: Re: [RFC V2 10/10] cxl: Add documentation for CXL UIO support. Date: Sun, 30 Aug 2026 15:23:30 +0800 Message-ID: <20260830072330.399591-1-junjie.cao@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <124323713.61787732282965.JavaMail.epsvc@epcpadp2new> References: <124323713.61787732282965.JavaMail.epsvc@epcpadp2new> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=192.198.163.9; envelope-from=junjie.cao@intel.com; helo=mgamail.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Shrihari, On Wed, 26 Aug 2026 11:04:10 +0530, Shrihari E S wrote: > +3. **Device 3 Extended Capability**: Enabled via ``x-uio`` on CXL type3 x-uio on its own doesn't get you Dev3: ct3_realize() adds it only when x-svc and x-256b-flit are set as well. It does set the HDM UIO bit with neither of them, which is the asymmetry I raised on 9/10. > +An example of 3 type3 devices with volatile memory below a switch. All the devices > +and ports support Unordered IO (UIO) feature which requires Streamlined Virtual Channel The topology below this doesn't advertise UIO through the switch. I ran it -- joined onto single lines, the indented continuations don't survive a paste -- and the upstream port reads 0x00000382 in its HDM Decoder Capability register, UIO clear, against 0x00042312 on cxl-rp. That's the gate in 7/10; worth re-running the example once it's settled. Many thanks, Junjie