From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) (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 BB04237AA7A for ; Wed, 15 Apr 2026 11:29:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776252566; cv=none; b=fGx1xluv+p+s0n6Mv9/woizqkHkue+AWF0BxWcf9Ob/GiS9iev/xultLP9FdSSWAJ2eHuAHyCAFtlSpoNsLFDl1NMHuetsbpuOjHsJbXCfNy1NTv7/vNMvM26l6mbCRsCi9fnFGBehpd/E139OXrD+mSXvWc/Ce66MnILktBPc4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776252566; c=relaxed/simple; bh=X9EONQDkzTf/uJLS6LvsRf2SakYDmKNPttPBDGJ7qFE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DlNDe4yah15DQRna7uEkp7Q5c583PHHCWiYSZG3uQ310iAIesfxeOHnrTtIzBIqhYJSwX1PHs3awUkEksFIlfOEy/xkq/AvjF+xp0Mm9wlOuWXu3PnefK/f0NWGymKYmJeD7R7atdvGljSL3GHpJrku2+aXiQ4Qb3QlpzaoWz4U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=NrkZgIDm; arc=none smtp.client-ip=91.218.175.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="NrkZgIDm" Date: Wed, 15 Apr 2026 19:29:15 +0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1776252562; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0deT5nTzAZM9jwtgeU6/XSQTQUWcP+shdfcj+l+woP8=; b=NrkZgIDmFnexpGPLRTk6BGtBWHW+Nb5UsUyG0DU10dMiXW5WGKh2aHVUOBLAYK5wwK/FW3 IrB3+fqJBc8gShpkGXjIZDErEC5gTkzlLA2fl3HZDYDFbSjCo1VMtpYF06kjOEBzVbU4Q6 Y/8Psk1bmkdXqLuNNvCqTft106v+OO4= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Baoquan He To: Youling Tang Cc: Baoquan He , Sourabh Jain , Andrew Morton , Jonathan Corbet , Vivek Goyal , Dave Young , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Youling Tang Subject: Re: [PATCH] crash: Support high memory reservation for range syntax Message-ID: References: <20260404074103.506793-1-youling.tang@linux.dev> 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: X-Migadu-Flow: FLOW_OUT On 04/09/26 at 09:55am, Youling Tang wrote: > Hi, Baoquan > > On 4/8/26 21:32, Baoquan He wrote: > > On 04/08/26 at 10:01am, Sourabh Jain wrote: > > > Hello Youling, > > > > > > On 04/04/26 13:11, Youling Tang wrote: > > > > From: Youling Tang > > > > > > > > The crashkernel range syntax (range1:size1[,range2:size2,...]) allows > > > > automatic size selection based on system RAM, but it always reserves > > > > from low memory. When a large crashkernel is selected, this can > > > > consume most of the low memory, causing subsequent hardware > > > > hotplug or drivers requiring low memory to fail due to allocation > > > > failures. > > > > > > Support for high crashkernel reservation has been added to > > > address the above problem. > > > > > > However, high crashkernel reservation is not supported with > > > range-based crashkernel kernel command-line arguments. > > > For example: crashkernel=0M-1G:100M,1G-4G:160M,4G-8G:192M > > > > > > Many users, including some distributions, use range-based > > > crashkernel configuration. So, adding support for high crashkernel > > > reservation with range-based configuration would be useful. > > Sorry for late response. And I have to say sorry because I have some > > negative tendency on this change. > > > > We use crashkernel=xM|G and crashkernel=range1:size1[,range2:size2,...] > > as default setting, so that people only need to set suggested amount > > of memory. While crashkernel=,high|low is for advanced user to customize > > their crashkernel value. In that case, user knows what's high memory and > > low memory, and how much is needed separately to achieve their goal, e.g > > saving low memory, taking away more high memory. > > > > To be honest, above grammers sounds simple, right? I believe both of you > > know very well how complicated the current crashkernel code is. I would > > suggest not letting them becomre more and more complicated by extending > > the grammer further and further. Unless you meet unavoidable issue with > > the existing grammer. > > > > Here comes my question, do you meet unavoidable issue with the existing > > grammer when you use crashkernel=range1:size1[,range2:size2,...] and > > think it's not satisfactory, and at the same time crashkernel=,high|low > > can't meet your demand either? > > Yes, regular users generally don't know about high memory and low memory, > and probably don't know how much crashkernel memory should be reserved > either. They mostly just use the default crashkernel parameters configured > by the distribution. > > For advanced users, the current grammar is sufficient, because > 'crashkernel=:[,:,...][@offset],>boundary' > can definitely be replaced with 'crashkernel=size,high'. > > The main purpose of this patch is to provide distributions with a more > reasonable default parameter configuration (satisfying most requirements), > without having to set different distribution default parameters for > different > scenarios (physical machines, virtual machines) and different machine > models. OK, do you have a concrete case? e.g in your distros, what will you set with this patchset applied? Let's see if it can cover all cases with one simple and satisfying parameter.