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 X-Spam-Level: X-Spam-Status: No, score=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39123C00A89 for ; Thu, 5 Nov 2020 09:59:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DEDCE2151B for ; Thu, 5 Nov 2020 09:59:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604570342; bh=zq/J9cOox+Td+rRWi/5wLhjGbno8/li76QcghCKkxuk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=yjWvSec11zqbbbMvgcsmnLP68XisTm9QxdxO4wtUWtfra3cJKsMSvZ05mT6bwFU8Q 7A6xyk4FwLKqoGA0bbqOsOsBYC+biuiu2e8yd6a1TRq/tz8tHGZhJpXpN/+YmsNOpw eGLFWdSVc5tjn+66/v8qPtxUzOhesmp7FArRZIrg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729227AbgKEJ7B (ORCPT ); Thu, 5 Nov 2020 04:59:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:36962 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725308AbgKEJ7A (ORCPT ); Thu, 5 Nov 2020 04:59:00 -0500 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 602272080D; Thu, 5 Nov 2020 09:58:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604570339; bh=zq/J9cOox+Td+rRWi/5wLhjGbno8/li76QcghCKkxuk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Vgwz/+MR/PU90hHu3OEUD77rEsIS2f4BFj/XUBKnlJ8+FcHcOrw/iE8Ddgl+AIHXQ FedhhInxamSEIVcYSPp10HEzobws3zWxEF51VfV1UKTL5FN6Fbw5Kmt9qw2bAiB/B5 25loWYK0+o8bybL5X7sHq5agZFDWr8PLQgWQL7Os= Date: Thu, 5 Nov 2020 09:58:54 +0000 From: Will Deacon To: Tyler Hicks Cc: Catalin Marinas , Pavel Tatashin , Rob Herring , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] arm64: Implement CONFIG_CMDLINE_EXTEND Message-ID: <20201105095853.GA7952@willie-the-truck> References: <20200921191557.350256-1-tyhicks@linux.microsoft.com> <20201103155952.GA4335@sequoia> <20201104120812.GA6632@willie-the-truck> <20201105054009.GA4472@sequoia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201105054009.GA4472@sequoia> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 04, 2020 at 11:40:09PM -0600, Tyler Hicks wrote: > On 2020-11-04 12:08:12, Will Deacon wrote: > > On Tue, Nov 03, 2020 at 09:59:52AM -0600, Tyler Hicks wrote: > > > On 2020-09-21 14:15:55, Tyler Hicks wrote: > > > > Provide the CONFIG_CMDLINE_EXTEND config option for arm64 kernels. This > > > > config option can be used to extend the kernel command line parameters, > > > > specified by the bootloader, with additional command line parameters > > > > specified in the kernel configuration. > > > > > > Hi Catalin and Will - Friendly ping on this series now that we're > > > on the other side of the 5.10 merge window. I hope it can be considered > > > for 5.10+1. Let me know if I need to rebase/resubmit. Thanks! > > > > Can you use bootconfig to achieve what you need? > > Thanks for mentioning bootconfig. I hadn't considered it. > > After reading the docs and code, I see a few reasons why I can't use it > out of the box: > > 1) It requires "bootconfig" to be appended to the kernel command line. > My proposed patch series makes it possible to append new options to > the kernel command line in situations where the bootloader is not > interactive. This presents a circular dependency problem for my use > case. > > A new config option could be added to force the enablement of > bootconfig but that would sort of be a single-use duplicate of > CONFIG_CMDLINE_EXTEND's functionality. > > 2) Not all kernel command line options can be configured using > bootconfig. For example, the "nokaslr" and "crashkernel=" parameters > are parsed/handled before setup_boot_config() is called. KASLR can > be disabled via a kernel config change but there's no config option > equivalent for "crashkernel=". Changing the "crashkernel=" command > line option is something that I need to support because a > development/debug kernel build often requires a larger reservation > and we find ourselves adjusting the "crashkernel=" value fairly > often. > > 3) External FIT image build systems do not yet support bootconfig since > it is so new. It is completely fair if you file this away in your > not-my-problem folder but simple kernel config modifications, as > needed for CONFIG_CMDLINE_EXTEND, are something that every image > build system is likely to support today. > > All that said, I do really like the look of bootconfig. Unfortunately, > it doesn't let me achieve everything I need. Ok, well thanks for having a look. A follow-up question I have is how is this handled on x86? They don't appear to have CONFIG_CMDLINE_EXTEND either afaict. Is it because their bootloader story tends to be more uniform? Will