From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753031Ab3BUBO1 (ORCPT ); Wed, 20 Feb 2013 20:14:27 -0500 Received: from mail-pb0-f41.google.com ([209.85.160.41]:48819 "EHLO mail-pb0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752539Ab3BUBOZ (ORCPT ); Wed, 20 Feb 2013 20:14:25 -0500 Date: Wed, 20 Feb 2013 17:12:42 -0800 From: Greg Kroah-Hartman To: Andy Ross Cc: Pavel Machek , "Kirill A. Shutemov" , Jiri Slaby , "Rafael J. Wysocki" , Len Brown , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH v2] vt: add init_hide parameter to suppress boot output Message-ID: <20130221011242.GB4961@kroah.com> References: <1361289224-10678-1-git-send-email-kirill.shutemov@linux.intel.com> <20130220014512.GC31018@kroah.com> <51244B35.8090006@windriver.com> <20130220044506.GA2728@kroah.com> <5124FFD7.8070708@windriver.com> <20130220205737.GB6597@xo-6d-61-c0.localdomain> <51254959.1020309@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51254959.1020309@windriver.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 20, 2013 at 02:08:25PM -0800, Andy Ross wrote: > On 02/20/2013 12:57 PM, Pavel Machek wrote: > >I'm sure something creative can be done with fake init that shuts > >the console up then execs previous init. No need to add more kernel > >knobs, I'd say. > > Fair enough, but some last words: > > That's argument is the "it's about logging" hypothesis again. Even if > it were possible to completely shut up console output (something > that's awfully hard in the general case when running on PC hardware, > and IMHO from a developer's perspective not even a good thing), that's > not the whole problem. The framebuffer console initialization does a > buffer clear and mode set, and that clobbers anything the bootloader > might have left on the screen prematurely, before userspace is ready > to throw up its own splash. Splash screens may be a silly > requirement, but they're still a requirement. Yes, they are a requirement in some situations, and if you look most distros have already solved this issue for you, by not using a framebuffer at all. Why not just do the same thing in your Android system as you do have full control over the hardware and the boot process. > And the suspend console problem is likewise at work: ideally you'd > like to know, for example, that the panel backlight is off before > suspending. But what happens in practice is that the kernel does a VT > switch to/from console 63 and the backlight wakes up (I'm not going to > pretend I have this bit completely figured out, but the problem is/was > real and this patch fixed it by suppressing the console visibility). My systems don't drop down to the framebuffer when suspending, I think you need to look at using a better distro :) > Now, the point that an in-kernel console is "going away" and thus not > worth augmenting with new APIs is valid. And this is a small patch > that's unlikely to be difficult to maintain in a custom tree. And as > we all agree there are other mechanisms that can be used here (even if > AFAICT they don't completely solve the problem), and indeed I'd love > to get surfaceflinger working with VT_ACTIVATE et. al. if I get a > chance. So I'm not going to cry if this isn't worth mainline. I don't see why this is even needed for surfaceflinger systems, as again, you have full control over the hardware and system so you don't even need a framebuffer console at all. thanks, greg k-h