From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) (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 14AA0241686; Sun, 30 Aug 2026 07:23:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.9 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788074637; cv=none; b=AUngEwOInhdVUbEZQKP/TyFu2+ywIl/btHSymGz+ShQ+Jz//y5I8RFZS4r26l651NkTMAR45vcK671E9X0fyBYY7p5oQx7HAmDwwsc5cchoBtWjzcTA81D2AcdssvaX1eJk1H6tpiw0AJCcDqx3u4g/5y5sX68HGNqJjmDkAcAY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788074637; c=relaxed/simple; bh=aQ3/GtP+7FT0jHBto6tRWGX4KNJFHv61L74w2OzzTPo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZQsOiDuoSopDM8t47MHbFoEZMsDgjfUkenRbBPGjD/PsGm2IRnNHXXbsUBxUbp2XOKI8wvbd/HTK/1oi4dKtBRgr17+Zz7UtsdM25Phvl0meOo7lV427bwMIa6+P8MhtgGa++HswY44n6Lbvzd/Jpe5eGj/qzgEhfeLdtc5YBW0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=PboeEHVO; arc=none smtp.client-ip=192.198.163.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="PboeEHVO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1788074635; x=1819610635; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=aQ3/GtP+7FT0jHBto6tRWGX4KNJFHv61L74w2OzzTPo=; b=PboeEHVO4ScInv/G1wz2owTOKfSpSzquTknjQduea9KgnRHUzfUsnFSe uKFhLz/QYZYg36Nc/PDUYa3Oye8j2ICx4PAUQUeZePzhAq6Fmoe6bnP49 Q+KDx0qD5Dhi++pfAVbm0NImPwbbX3iFP7U1gliHCzDfhuaJEQz08cEdf XthN8BZBloahFKijwo9KefpQmXRy+s1zdABV1+QfVQci1Kf95Uau+eeC9 VJmbiVOW3o050DTNz2ddH812v9MLBeJiAGgbKufDeo50DG+JnZAUeX6Vl aIsLN2ARYBbGpOf5WcBcS+NUKi+ezForLa8H6mr14Qsk/Bysaz6Tt2JsF Q==; X-CSE-ConnectionGUID: WUgZhaLzQNKjaEcLgvFfig== X-CSE-MsgGUID: N+8Fg1tvQhGMXo9Irpfs7g== X-IronPort-AV: E=McAfee;i="6800,10657,11890"; a="99177853" X-IronPort-AV: E=Sophos;i="6.25,251,1779174000"; d="scan'208";a="99177853" 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> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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