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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 2D6F9C43458 for ; Thu, 9 Jul 2026 10:26:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TPdVHdBqE78Tyd4PBWnjxJl0mWtpdEwQn28B3/SGb/w=; b=FE1BzZuQva36C8B+zBSq147Y3p 1B0QzMnJe1H/Cenwq8iy0PzaYvvQVec3oTF/HIhi8XYbRx0XKnHphPILozEDAl1qHJ99Eci1tz0n1 AMcHohiQ96DcFp0YqMUi2FU12aQjb2bBlm8nJlqcR4LYwSZlsGsuy3RjtUjaIUYwT5ERHfFE11gv7 fxllDW2tjgYLA6Tv3hNkwKpWURl9C4MZhPN0C2CD/HJYQLoBTJpAP0ZajBuFsRQz9X7bZoI55BV7E kvfwpkZNqaxxlUpIdqF6HowrOvYtdOdNgyXVR2S7Rth73QSyM0QAxgb5O+rGMWxCBLLC2FrX8bzvT SI8GkSgA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1whlxS-00000001wDf-0LFR; Thu, 09 Jul 2026 10:26:18 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1whlxQ-00000001wDJ-1wEL for linux-arm-kernel@lists.infradead.org; Thu, 09 Jul 2026 10:26:16 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 748246001A; Thu, 9 Jul 2026 10:26:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85ADD1F00A3A; Thu, 9 Jul 2026 10:26:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783592775; bh=TPdVHdBqE78Tyd4PBWnjxJl0mWtpdEwQn28B3/SGb/w=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=DTci9JOWIGHKfBoQb3CBfSV1SkaFony1B9cQxR/582XmSaBE0WcAVXehCunpqUihN FcSL9fchO9EriU8hNo2GAlseP1MoOnrrdV/AyxTRDEq1Ol5ptedub8IwkszrzuqoEY swWIWr9i1t5L/RQDig18MQO15ZxE+C2JBWaEWTU4bG25OzyCJ51zbowDDHd3UFF5XE f3PMBjDE+iF6kT+TtVb99M0QRkFKJaZDrOEDpLo7xKZuZMAIMY60GLDzL1TodfoyH4 Wv9HTOujAGR4LZKtOqXySgP/XHA8H65aLq/KqyUT0ASQ0/EqW7VhIL1rPzLeQcwxQS uTq86OLThc6Rg== Date: Thu, 9 Jul 2026 11:26:08 +0100 From: Sudeep Holla To: Shyam Saini Cc: Catalin Marinas , Sudeep Holla , Mike Rapoport , ardb@kernel.org, david@kernel.org, will@kernel.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, bboscaccy@linux.microsoft.com, bp@alien8.de, dapeng1.mi@linux.intel.com, ebiggers@kernel.org, elver@google.com, enelsonmoore@gmail.com, feng.tang@linux.alibaba.com, gpiccoli@igalia.com, kees@kernel.org, kuba@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lirongqing@baidu.com, peterz@infradead.org, rdunlap@infradead.org, tgopinath@linux.microsoft.com, tony.luck@intel.com, Lorenzo Pieralisi , Hanjun Guo Subject: Re: [RFC v2 PATCH] reserve_mem: add support for static memory Message-ID: <20260709-educational-nimble-seagull-5fc031@sudeepholla> References: <20260630170911.43521-1-shyamsaini@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jul 08, 2026 at 05:37:33PM -0700, Shyam Saini wrote: > Hi Catalin, > > On 08 Jul 2026 11:00, Catalin Marinas wrote: > > Hi Shyam, > > > > Adding Lorenzo, Hanjun, Sudeep. > > > > On Tue, Jun 30, 2026 at 10:09:11AM -0700, Shyam Saini wrote: > > > Following up on this, As Mike pointed that reserve_mem is best effort > > > reservation mechanism, so what is the recommended reliable Linux > > > mechanism, if any, to reserve a predetermined memory range during > > > early boot on ARM64/ACPI platforms for warm boot scenarios? KHO is > > > one option, but I'm specifically looking for a solution that preserves > > > the region across warm reboots. > > > > If you need ramoops-like support, I think ACPI ERST is a better fit and > > we don't need any memory reservation tricks. I'll let the arm ACPI > > maintainers comment further. > > > > while this patch mentions use case of ramoops, there are other uses cases that > requires predetermined memory reservation at boot time, one of them is PMEM. > Like Mike pointed out in this [1] thread, we don't seem to have an > equivalent mechanism for reserving predetermined memory on ARM/ACPI > platforms, as is available on ARM/DTS based platforms. > Indeed, it was been discussed in several forums in the past but AFAIK there is no conclusion or a direction towards solving this yet. -- Regards, Sudeep