From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Pantelic Subject: Re: Trouble with newer kernels on Gumstix Overo boards Date: Wed, 22 Jun 2011 08:57:06 +0200 Message-ID: <4E019242.1050503@gmail.com> References: <20110621072220.GA21159@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:46329 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751154Ab1FVG5J (ORCPT ); Wed, 22 Jun 2011 02:57:09 -0400 Received: by fxm17 with SMTP id 17so427142fxm.19 for ; Tue, 21 Jun 2011 23:57:08 -0700 (PDT) In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Daniel Mack Cc: Tony Lindgren , "linux-omap@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "Gadiyar, Anand" Daniel Mack wrote: > Well, it doesn't really affect me as I just use this as a development > platform for now. But please consider that there is hardware out there > which gets software updates through automated download and install > procedures. In such cases, you want as little dependencies between the > bootloader and the kernel, so you can boot both older and newer If you want *minimal* dependency, then a compiled-in command line is the way to go and the bootloader only providing a few board identifying tags > kernels (and full software distribution images) with no pain. Or maybe > quickly switch from one version to the other for testing. Depending on > the complexity of the system, the bootloader might also add extra > parameters to the cmdline dynamically. AFAIK there is way to have the bootloader provided cmdline appended to the compiled-in one > The serial console change breaks this approach, at it forces the > kernel to ship its own CMDLINE and override the one the bootloader > provides. I'm sure this is a problem that affects people out there. FWIW, for our firmware update deployment it's not a problem at all, since we do *not* want to rely on a kernel commandline provided by the bootloader for the exact same reason. Kernels change and thus the kernel command line belongs to the kernel. What does not change is e.g. the board id or revision or mem size, that (and only that) is provided by the bootloader to the kernel. From mboxrd@z Thu Jan 1 00:00:00 1970 From: vladoman@gmail.com (Vladimir Pantelic) Date: Wed, 22 Jun 2011 08:57:06 +0200 Subject: Trouble with newer kernels on Gumstix Overo boards In-Reply-To: References: <20110621072220.GA21159@atomide.com> Message-ID: <4E019242.1050503@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Daniel Mack wrote: > Well, it doesn't really affect me as I just use this as a development > platform for now. But please consider that there is hardware out there > which gets software updates through automated download and install > procedures. In such cases, you want as little dependencies between the > bootloader and the kernel, so you can boot both older and newer If you want *minimal* dependency, then a compiled-in command line is the way to go and the bootloader only providing a few board identifying tags > kernels (and full software distribution images) with no pain. Or maybe > quickly switch from one version to the other for testing. Depending on > the complexity of the system, the bootloader might also add extra > parameters to the cmdline dynamically. AFAIK there is way to have the bootloader provided cmdline appended to the compiled-in one > The serial console change breaks this approach, at it forces the > kernel to ship its own CMDLINE and override the one the bootloader > provides. I'm sure this is a problem that affects people out there. FWIW, for our firmware update deployment it's not a problem at all, since we do *not* want to rely on a kernel commandline provided by the bootloader for the exact same reason. Kernels change and thus the kernel command line belongs to the kernel. What does not change is e.g. the board id or revision or mem size, that (and only that) is provided by the bootloader to the kernel.