From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f173.google.com (mail-qt1-f173.google.com [209.85.160.173]) (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 EC24D3921E9 for ; Tue, 13 Jan 2026 13:55:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768312560; cv=none; b=ILJpWCJt0564U+4nVgQ7a8K8en3F3sWJPvZhT9IMvJMXdOZ9FXNhjulFwePFab6zylYlpny4thbwTjrBsR6xovYQBEEjg9PDYuAVsMACsNfaKqTd8VydL6ifvsJjg88+DQplP2TQsM/N0N+Ql5hMe5djo3O21Dicf+NogWGL7mI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768312560; c=relaxed/simple; bh=xBKJZJaq58dkfEBp5UADogC3I/NHOLgLZ8uI94yH9Qk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ehgJTMUa0vEoXWzxg1kaZkpF5SvZJBNNuN2y0p3AhbxuHvW60Qum50mDR4Jo2R6WoNNnLjLlZJDcjqQYzOJKLR27fFq7aAmZeVaC96CRlUkA1Az+etddRVEoiKbIK4V6hvsYtp4l7LTvvY0DDE+iz0E7S4At+RHH+OF8Tgn2PzI= 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=t0ifdMef; arc=none smtp.client-ip=209.85.160.173 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="t0ifdMef" Received: by mail-qt1-f173.google.com with SMTP id d75a77b69052e-4f1b4bb40aaso40934691cf.3 for ; Tue, 13 Jan 2026 05:55:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1768312544; x=1768917344; 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=7MgVKM12PPuEhN+GtLeIhws/qU0BjDyGSzafJ6+BtXw=; b=t0ifdMefP9ykjBGPRfjjbhG1+5ijyYk/Mmq1w8U2njTzZjgUC2IJJZA2L30eo754Gb WYyQFk8YZYyAkDY/oOqpHVYrshWzIrlRSZ4eYqr+40TjdG5snOfand6+8VrKguIZ8U8m 793vfw25VSRH7jcgWcdWepzonGFdyqPaZohn5+n2eVzrHGKynUyz67LjYnBG5ahsulvS ZNqlfeauugOVrrn600O9Lec4XYWPnUz0Nsu+BN/AZ+ydZJsD3DjI9G3fZTutAO9ES8/+ GZhXvdROgb0BOCHPm3K9ZG+EFMYViuSWmOJ2vMttd6L/CSxpbEKgsSpsdafpQdHrGPti 9PmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768312544; x=1768917344; 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=7MgVKM12PPuEhN+GtLeIhws/qU0BjDyGSzafJ6+BtXw=; b=py2WxWKB6s1uaNzn0SwFaKoKfefsZwKhunsYF218l/vSXzXbav605rkwRFvht7LZS6 sPsQ19F5Y4gX8/lVVyW//tNXjc26U+miO34LaapnnuJ6jan4B9ol1Ltgz0puygEr8zA1 G5QdO49wSFRKntQZDoRf3SpdeGwle2OP9bSXzqPBx0DxU1PQ4Zr7JNBavD+syZekqfjb 1sXALLltiAa4uSxb9SowegqQ8yXSN7WJ0UvCIpRWUzRg6XU+pn3fYXyZ8jJA5HpEtDRd WZMr8gfYNRI2SxxOoubuau+WiP6mNGkXDVYOYlDSz/zuMUOypgnJrVIQV+r5u4g7i8Ak /T9A== X-Forwarded-Encrypted: i=1; AJvYcCUdhNQUnIQw9l1wTPlzYeVkXVYTO3J4NwEVljPHCS3b5EXzwGIDGlhIjoCXXLCemq6vPno8S9Iu8oc=@vger.kernel.org X-Gm-Message-State: AOJu0Yx7bh8Nfx5wsg51U5HEDqnusXjNjlCeSQWbPixhhTkvVW/Anjwe AfQHcSq0fNuEhRNx8Ll1YeYwY3X3R5rfjFq7vOipRfGpfOkIERw/W5duUdqDdp5C/ow= X-Gm-Gg: AY/fxX7Ae4QryFDBRizNvrZxdf0sHwp35rPF0Pl6lWq3o/WzFeV5ENc0JqlpOeGJIRN I/LHwYkitW/jySGLNkI8bMRcDXFAtq5CGP3bSVFzaJHl7nJY+ugvGxo9QAezwrQed/pCPNeg4F6 o1bsAkd6caUxHfHpG+YLTtrXBgw2YyypA76bxXAOEr47DkaknMBSK4mfEjg+uTsrHGWU3oBo2gu fAyc0Tsf36OIOLysRANnzzgBKT7Jk0Dh+WEzmD3iW7YYgpsenDVnzc4zTFPKQnogKdaBGsJXVFv N+km7rkrvh5Oe36oKUPpBPJJ1ZszK+3lybaeTrOhkhuJCf7n3VxFKZzxS69NmghD5yMuZTqSEUD ApIRO5xO7diIL7aqWWmWgloPgIaZv1wxyIXmD+LtLpPBWKzReUBtrm7c/ZbetwLB4WX6Yh3uuLW jHtxRYPFIPSj2C2lnQiCPLEYHS6z16lxCXrvZ+sbJLmpzNhQyPIF9n5wVV2VcMf3gPhXjJuOE7+ RTkxElt X-Google-Smtp-Source: AGHT+IE3kt3s0DLMOPwLiSdVdgOeQtw2p38PZVQ2YGk1VFWgC3l7L3gBOxrJnRu4rRu8OIwLGEfYwQ== X-Received: by 2002:a05:622a:244a:b0:4ee:49b8:fb4b with SMTP id d75a77b69052e-4ffb4a9aad2mr295553631cf.66.1768312543593; Tue, 13 Jan 2026 05:55:43 -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 6a1803df08f44-890770cdfb0sm158070046d6.6.2026.01.13.05.55.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Jan 2026 05:55:42 -0800 (PST) Date: Tue, 13 Jan 2026 08:55:07 -0500 From: Gregory Price To: dan.j.williams@intel.com Cc: "Cheatham, Benjamin" , linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com Subject: Re: [PATCH 4/6] cxl: add CONFIG_CXL_REGION_CTRL_AUTO_* build config options Message-ID: References: <20260112163514.2551809-1-gourry@gourry.net> <20260112163514.2551809-5-gourry@gourry.net> <05591180-c299-42e1-b8a0-ddd74c5f2174@amd.com> <6965cabc68fda_875d100c0@dwillia2-mobl4.notmuch> 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=us-ascii Content-Disposition: inline In-Reply-To: <6965cabc68fda_875d100c0@dwillia2-mobl4.notmuch> On Mon, Jan 12, 2026 at 08:31:56PM -0800, dan.j.williams@intel.com wrote: > Gregory Price wrote: > [..] > > > If you remove the 'auto' mode earlier on, then you can just drop the first sentence here. > > > I'd also add a note about when a DAX region can be failed to be created (i.e. BIOS already > > > set up and onlined the memory). > > > > > > > I think I'm just going to drop this entirely, probably this was just too > > ambitious trying to create an easy transition from dax to sysram for > > auto regions. > > > > The reality is BIOS-configured decoders "is NOT the way" (TM). If BIOS > > configures it - it's DAX, otherwise the user gets a choice (or they can > > tear it down and rebuild). > > Is the plan here to "whither struct memory_block"? I can see value in > starting the deprecation process given the problems Hannes points out > and BIOS alignment causes massive numbers of those things to show up. > > If yes, then even if it is DAX the distro might still want the option to > only allows for region-scoped "hotplug" rather than memory_block-scoped > "online". This was not an intent, but maybe? I'm not sure what the larger implications of this are - except that maybe poisoned regions of memory might take out larger chunks of hotplug memory. Other things may depend on memory block size in unexpected ways. I think maybe lets tuck that away until after we get region-scoped hotplug. Maybe it would look like this Step 1: Region-scoped hotplug that uses all the blocks Step 2: memory hotplug callbacks that disallow any hotplugger (except emergency hotplug?) from acting on individual blocks We already want this for online_movable, just defer a bit and make the guarantee stronger. Step 3: deprecate memory_block for something else? make memory_block variably sized with some base alignment? ~Gregory