From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C710C36C599; Tue, 17 Feb 2026 14:43:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771339417; cv=none; b=oOzv66lM4ya3h2IiljxgrrDXPsCB2+pMbtIEeJA+xniff1kUSVvUL5Ij57Bwnyno3booEhBJod5wX3IIGgwVCdkvWCTAPO5VI070FCsZ8N7zLe5OuBRuBFYHw7qkGenpMyenepwdelY4kRw7DTOyjxcwLwgqcm/nV0f0KEdz+A4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771339417; c=relaxed/simple; bh=o002gwLxpjE0faJ0YPgVrlNVLmOsAQCdTKOXcK4c3sM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qzVpjvmNTGtjtFIihHxgsFW0tNRPKDI+IQ6WnKO585R+CXbFoH/ha9Yi31j+Fjzlu3uqXaISiLlNRe6HikVKEmCO0SDCQHoE+ZlLU1KWPt0zZ4ZG+Eit7QSHT4vQMuVD4XFUUaig79rjs9NXKhZqC0YvBcB2rZ34qajKgIufP9U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DC7261477; Tue, 17 Feb 2026 06:43:28 -0800 (PST) Received: from [10.1.30.186] (XHFQ2J9959.cambridge.arm.com [10.1.30.186]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 841BF3F62B; Tue, 17 Feb 2026 06:43:33 -0800 (PST) Message-ID: <20e320d2-749a-4379-a236-5dbe3d52b07f@arm.com> Date: Tue, 17 Feb 2026 14:43:31 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6.6 0/3] arm64: Speed up boot with faster linear map creation Content-Language: en-GB To: Greg KH Cc: stable@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jack Aboutboul , Sharath George John , Noah Meyerhans , Jim Perrin References: <20260217133411.2881311-1-ryan.roberts@arm.com> <2026021700-chafe-jurist-cb24@gregkh> <17c9efaf-6c33-4485-bde2-345cc15ac000@arm.com> <2026021718-citrus-parakeet-dc60@gregkh> <7f30a8e4-49c3-421d-be05-08afb544aa41@arm.com> <2026021758-subsidy-tinfoil-ee2c@gregkh> From: Ryan Roberts In-Reply-To: <2026021758-subsidy-tinfoil-ee2c@gregkh> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 17/02/2026 14:26, Greg KH wrote: > On Tue, Feb 17, 2026 at 02:21:30PM +0000, Ryan Roberts wrote: >> On 17/02/2026 14:10, Greg KH wrote: >>> On Tue, Feb 17, 2026 at 01:58:36PM +0000, Ryan Roberts wrote: >>>> On 17/02/2026 13:50, Greg KH wrote: >>>>> On Tue, Feb 17, 2026 at 01:34:05PM +0000, Ryan Roberts wrote: >>>>>> Hi All, >>>>>> >>>>>> This series is a backport that applies to stable kernel 6.6 (base v6.6.126), for >>>>>> some speed ups to enable significantly faster booting on systems with a lot of >>>>>> memory. The patches were originally posted at: >>>>>> >>>>>> https://lore.kernel.org/linux-arm-kernel/20240412131908.433043-1-ryan.roberts@arm.com/ >>>>>> >>>>>> ... and were originally merged upstream in v6.10-rc1. >>>>>> >>>>>> I'm requesting this be merged to stable on behalf of a partner who wants to get >>>>>> the benefit of this series in Debian 12. >>>>> >>>>> Why can't they just use a newer kernel version (i.e. 6.12)? Surely they >>>>> would be able to justify moving to a newer kernel for performance >>>>> reasons, why enable them to stay on an older one, just delaying the >>>>> inevitable upgrade they will have to do anyway in a year or so? >>>> >>>> I can't answer this presicely, but I did ask and push for that approach. As I >>>> understand it, they are stuck with Debian 12, which is stuck with kernel 6.1. >>>> The Debian maintainer apparently requested that these go through stable in order >>>> to get them into Debian 12. >>> >>> I understand the position of Debian not wanting to take patches for new >>> features that are not already upstream, but really, Debian offers a >>> newer kernel for hardware that wants to use it for things like this, >>> right? Why not just use that instead? >> >> Let me go push a bit harder. But I expect we are in the grey zone between bug >> and feature here; this is a performance bug fix, not a new feature. By >> selectively backporting I'm guessing they are avoiding the risk of new features >> that a new kernel brings introducing new bugs? I'm guessing there is a higher >> qualification bar for that. > > That's a broken "qualification system" if that is the case, given that > the patches that flow back into stable kernel releases should be > triggering "full qualification" if anyone actually paid attention to > what goes into there :) > > Anyway, good luck! And same for 6.1.y, if they are ok with 6.6.y, why > would they even care about 6.1.y? The request was only for 6.1. I did 6.6 as well for continuity; I didn't want it to get slow again if they moved from 6.1 to 6.6. It's already fixed in 6.12. > > thanks, > > greg k-h