From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 61E0A401A13; Thu, 9 Jul 2026 10:26:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783592776; cv=none; b=DQQh47EACezCzAwWUxDECoyC8Y/YP1G4gQm4TPnjgnuVh3UzUMO3cOKwY21QEu8OU+MHbQzemZg1sv+4aYaZcJPPOdBFZaB0l5v5MDu8l2Sx1tTGVEU6IH1T/cDeQj3lxiFdn2XHoPm9d83Gx9JpQyxnVtjmM9O+p0MFVKqEIRY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783592776; c=relaxed/simple; bh=5HjcXSURjY/ODwJG9TdR5EZq9MDPqVY6MvHd7UOAfrM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kP98fGMbRLXpyGNSj3BwjmYF7PZ7xAyT3ucvrGUxHekqZqXLJsiu0wOQTDsYEInYKy5VQonn1DG6CD/lFgosk27ZyOt9L/WQa5Fcrly7fUSI29S3Lmbt59CmVuvfKyXSjeJkWYru4M3/hffC+vsSvqnuPcbYS/m8Y3TNxIawCQc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DTci9JOW; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DTci9JOW" 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> Precedence: bulk X-Mailing-List: linux-kernel@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: 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