From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f66.google.com (mail-qv1-f66.google.com [209.85.219.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E9EBB328610 for ; Fri, 19 Dec 2025 14:32:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766154732; cv=none; b=cvNAOWj0n578spdiASwi+nBr9iFPifevoctHlB4AeZbI0Q0VIKxnUamOqiAroxuEX13xiefaoFOo+QBlXaCXIK64gmU0eE7XnMHIZnE+WCkl2gjnj0y3dHmDOHcpg/Xy/BxVuIvEHkWPqV7Y9r/MpPeliXTndAm9NEKsPd4vagc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766154732; c=relaxed/simple; bh=ADWK1K6u6t0CaWFJITvqzw+3tp6y+TaCRw5mAd3q2gU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QdC3gw/QGzQQ857qneqffs6u4mhYdlllYKGt93csrkm6fAcKURTpU+o2YxHO3xp3qhsgfniC3ueY7dkdXGbINOsMrYfCv6Xp06YEgbhAWCfIpp7wriay81VFFlHFbkpI+BM5+Lg1lFmETdXO4BBRk1bRyZlKzAahLbs+bHbWJ/s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net; spf=pass smtp.mailfrom=gourry.net; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b=gNDdAWLp; arc=none smtp.client-ip=209.85.219.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gourry.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b="gNDdAWLp" Received: by mail-qv1-f66.google.com with SMTP id 6a1803df08f44-88a26ce6619so17900026d6.3 for ; Fri, 19 Dec 2025 06:32:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1766154729; x=1766759529; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=Ivd5VUDwxKrJjsOzp1+SZHitpb44btNy0UY1qm1oXXk=; b=gNDdAWLpTkL4yzLz4kJEKfQZiQ04pNofmdooFUhwckx3MWcSeUkw67hsz5q4w83T3E u2IPd1JsLAuI6zYH1TnyTsLCOuFIkunOb3tbvCKnFouEtyhOY3vFKSXB5ugyQs7NpeFo w3s+GpsPfxDiajzMU7NbnWR2+X9UDUm+L6JEt+/5qWmvzQY9dJwr5a6ePtILcjlXDuWk IL5uBNqNwlbgWtM1nq61Ubu5fYEhI4VyXFupZAlOXa6iDxPJr4QOK5Vf66O82m9s+UZi QGvMUJZMEnTQ02ZK/bE8v8Ag/GlsYIvjkVzhKEMaYWDQGAhV3vtS4oQ2Zt7DIlTrvFDx Ihbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1766154729; x=1766759529; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Ivd5VUDwxKrJjsOzp1+SZHitpb44btNy0UY1qm1oXXk=; b=MEAFvveua/Cr29KTp7EO+uGG7rRtxexP0b3SLXHzBoKBVOOS6FBl4DMJtLK7Y/v/vo +pagRj1HQVW+8RhpJs+C7Gy4W7R9w21wjlI6xEGeTsxC2veppHYP7O5Rr3n5ZCHmc4dy AxUeNbTOKhg2kiCEtQk0tFr0lw9nb6fXXXTXby7agYAUkWSMhEu/ZY5sGwadWDNrk0T6 1XOrZ8EQ2UefKd5kFUta5BryEf3iLTEH0oHRE1scuZXAZ3FYVGyT6KzBfv6/Z336wQ8h ZoZygb9KZNrhQCxYO12T1dTAyZvbOdw0oIqehcRngEUGrqVRkV6FbucU2z7j4TZI37Eh 8Sug== X-Forwarded-Encrypted: i=1; AJvYcCUj+FeUXNiBCnCcCpPH767Yh5y0Yf9dKX6jpNTHgSu4ZXGOtxDQyGwnqYh1QQ5ITsHHBqPHBv0LqDg=@vger.kernel.org X-Gm-Message-State: AOJu0Yymk4wRfRdQvh5CDK5DZjwDJCZxAZ3qebfE3A2tk6bvKS+Qr+V8 6f91WwRzebqIKgazFA/uB+IooNvbbm4eJZtUdroD9aCAnGw4R2wOO2f/+TyzLPgE4dw= X-Gm-Gg: AY/fxX6uqpLiBsNIe0zoQOtiEB6zRiaGNx4bmF4YODSznZCRvuQTXA7a1hX5pNjvPc0 BXzxYxMmcntp94eglHj73pxwVS8YSr0Cp01872Zuy9bCMa/v32QB4pTGPWx74iCTFwu9iLBGFES TOS5j5FHPkE2+6wk9tl5dKIN+mSh77pOHPXvts6hydb3LqU+/5DS5+GbqUGlcbqFrYGdahC8Jhv 0ViPEtx4Gx6oYqSRjGok4GOpJZTE360ZDxNpCLp4W1O8pC35PTPng+26y/j4jMoy92PWV4iZChc PlIODhcMqsKDQzHiV2BNaHOzZUHqWIVOJosHRcM0Ln5a8QHPdWdimkwV8mMurG+rBpzc+hBtflP zynQFCgC28ndAOcTbI9WxVliAfOzFwohmOJQJOQolb8dElEcodnjfRevJzj8Rt+NruUzvT7JYVa Bqgctkw0WIkRX0pXxFu0d+eQ4DDtOERjkI7Srm0tbc7P/a8fbk/nUwy2KyFNakS5fy4w3WJQ== X-Google-Smtp-Source: AGHT+IHFFb9WYMCs70KCnwOLuU8Gjvo2loQhh9U7/SRr9OdjbdGz6to5W9XjQQ2TooWYSjdCemC3fg== X-Received: by 2002:ad4:5003:0:b0:88a:347c:4117 with SMTP id 6a1803df08f44-88d85bae7c9mr33202336d6.19.1766154729462; Fri, 19 Dec 2025 06:32:09 -0800 (PST) Received: from gourry-fedora-PF4VCD3F (pool-96-255-20-138.washdc.ftas.verizon.net. [96.255.20.138]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-88d997aeef5sm20208696d6.27.2025.12.19.06.32.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Dec 2025 06:32:09 -0800 (PST) Date: Fri, 19 Dec 2025 09:31:32 -0500 From: Gregory Price To: Jonathan Cameron Cc: linux-cxl@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, dave@stgolabs.net, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, corbet@lwn.net Subject: Re: [PATCH v2] Documentation/driver-api/cxl: device hotplug section Message-ID: References: <20251218170747.1278327-1-gourry@gourry.net> <20251219105518.00005ca6@huawei.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251219105518.00005ca6@huawei.com> On Fri, Dec 19, 2025 at 10:55:18AM +0000, Jonathan Cameron wrote: > On Thu, 18 Dec 2025 12:07:47 -0500 > Gregory Price wrote: > > > + > > +Multi-Endpoint Memory Device Present at Boot > > +-------------------------------------------- > > +A hot-plug capable CXL memory device, such as one which presents multiple > > +expanders as a single large-capacity device, should report the maximum > > +*possible* capacity for the device at boot. :: > > + > > + HB0 > > + RP0 > > + | > > + [Multi-Endpoint Memory Device] > > So this is the weird switch as end point thing? Maybe a reference. > My guess is these will go away as switch and memory device vendors catch > up with the spec, but maybe I'm wrong. > I guess I just don't want to dictate the innards of a multi-endpoint memory device. It *really really* implies there must be some kind of switch inside - but that switch might not even be runtime programmable or discoverable (basically all the settings get locked on boot and it becomes passthrough). If you'd rather just not have this section at all, I'm ok with that. The switch case below this covers the base case for a switch-based device where everything is programmable. > > + _____|_____ > > + | | > > + [Endpoint0] [Empty] > > + > > + > > +Limiting the size to the capacity preset at boot will limit hot-add support > > +to replacing capacity that was present at boot. > >