Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756737AbbGGLcr (ORCPT ); Tue, 7 Jul 2015 07:32:47 -0400 Received: from pandora.arm.linux.org.uk ([78.32.30.218]:53670 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754526AbbGGLck (ORCPT ); Tue, 7 Jul 2015 07:32:40 -0400 Date: Tue, 7 Jul 2015 12:32:13 +0100 From: Russell King - ARM Linux To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: Laura Abbott , Grant Likely , Rob Herring , Will Deacon , Ivaylo Dimitrov , Sebastian Reichel , Pavel Machek , Tony Lindgren , Andreas =?iso-8859-1?Q?F=E4rber?= , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org Subject: Re: [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry Message-ID: <20150707113213.GC7576@n2100.arm.linux.org.uk> References: <1436214373-12969-1-git-send-email-pali.rohar@gmail.com> <1436214373-12969-6-git-send-email-pali.rohar@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1436214373-12969-6-git-send-email-pali.rohar@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2366 Lines: 52 On Mon, Jul 06, 2015 at 10:26:13PM +0200, Pali Roh?r wrote: > Legacy bootloaders can pass additional information for kernel or legacy > userspace applications. When booting DT kernel then ATAGs structure is not > more visible after running kernel uncompress code. This patch stores full > ATAGs structure into DT "/chosen/linux,atags" entry, so kernel can later > reuse it and export via /proc/atags to userspace. I think you need to go through your commit messages and improve them, especially the ones with "TODO" in them. As long as there's still things to be done, they're obviously not ready for merging. Moreover, exporting the ATAGS is questionable, even _if_ there are non- kexec programs making use of this. The ATAGs have _never_ been exported to userspace when kexec disabled is the kernel - it was introduced for kexec, and has always had this: config ATAGS_PROC bool "Export atags in procfs" depends on ATAGS && KEXEC default y Now, the fact that someone decided to start using it is pretty sad, because it means that if you disable KEXEC, userspace breaks. That's not a kernel regression in any shape or form, because /proc/atags has never been there without KEXEC enabled. That's a userspace bug, plain and simple. Given that, I'm in two minds about whether to accept the last two patches which make this more than just "for KEXEC use to enable a KEXEC kernel to be booted." Had it been provided without the KEXEC conditional, then I don't have a problem with these two patches. It also sets a precedent: by adding this into DT, it is creating a new DT ABI as well, and we'll end up seeing dts files with an ATAG block patched into them. Are the ATAGs at a fixed address on the N900? Can that be handled in some kind of legacy file for the N900 which calls save_atags() on it, so we don't end up introducing yet more stuff that we have to maintain into the distant future? If not, what about copying a known working atag structure into a legacy file for the N900? -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/