From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933891AbcECRVm (ORCPT ); Tue, 3 May 2016 13:21:42 -0400 Received: from mail-wm0-f42.google.com ([74.125.82.42]:32772 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756180AbcECRVk (ORCPT ); Tue, 3 May 2016 13:21:40 -0400 MIME-Version: 1.0 In-Reply-To: References: <1455889559-9428-1-git-send-email-mcgrof@kernel.org> <1455889559-9428-4-git-send-email-mcgrof@kernel.org> <1456740770.4666.366.camel@infradead.org> <20160229185606.GD25240@wotan.suse.de> Date: Tue, 3 May 2016 10:21:37 -0700 X-Google-Sender-Auth: FBY5ayCfAm1HGGtnU3p0u-x0KsQ Message-ID: Subject: Re: [RFC v2 3/7] firmware: port built-in section to linker table From: Kees Cook To: "Luis R. Rodriguez" Cc: David Woodhouse , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "x86@kernel.org" , LKML , Andy Lutomirski , Boris Ostrovsky , Rusty Russell , David Vrabel , Konrad Rzeszutek Wilk , Michael Brown , Juergen Gross , Ming Lei , Greg KH , Arnd Bergmann , linux-arch , Russell King - ARM Linux , "benh@kernel.crashing.org" , jbaron@akamai.com, "ananth@in.ibm.com" , anil.s.keshavamurthy@intel.com, "David S. Miller" , Masami Hiramatsu , Andy Shevchenko , "xen-devel@lists.xensource.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 3, 2016 at 10:10 AM, Luis R. Rodriguez wrote: > On Tue, May 3, 2016 at 10:07 AM, Luis R. Rodriguez wrote: >> Thanks! Can you confirm if any Android or Brillo builds are already using it? > > Also more importantly, any chance you can provide any technical > reasons why initramfs cannot be used, or it was decided to not use it > on these systems? It should help others in the future as well. In Chrome OS, the kernels are built specifically for the hardware they're going to be on, so an initramfs was seen as a needless additional boot step. Since Chrome OS was heavily optimized for boot speed, it was designed to not need the initramfs at all. This is actually enforced by the read-only boot firmware, so there's no trivial way to _start_ using an initramfs on (existing) Chrome OS devices either. -Kees -- Kees Cook Chrome OS & Brillo Security From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: Re: [RFC v2 3/7] firmware: port built-in section to linker table Date: Tue, 3 May 2016 10:21:37 -0700 Message-ID: References: <1455889559-9428-1-git-send-email-mcgrof@kernel.org> <1455889559-9428-4-git-send-email-mcgrof@kernel.org> <1456740770.4666.366.camel@infradead.org> <20160229185606.GD25240@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-wm0-f45.google.com ([74.125.82.45]:37419 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756177AbcECRVj (ORCPT ); Tue, 3 May 2016 13:21:39 -0400 Received: by mail-wm0-f45.google.com with SMTP id a17so51696461wme.0 for ; Tue, 03 May 2016 10:21:38 -0700 (PDT) In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: "Luis R. Rodriguez" Cc: David Woodhouse , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "x86@kernel.org" , LKML , Andy Lutomirski , Boris Ostrovsky , Rusty Russell , David Vrabel , Konrad Rzeszutek Wilk , Michael Brown , Juergen Gross , Ming Lei , Greg KH , Arnd Bergmann , linux-arch , Russell King - ARM Linux , "benh@kernel.crashing.org" , jbaron@akamai.com, "ananth@in.ibm.com" , anil.s.keshavamurthy@intel.com, David S On Tue, May 3, 2016 at 10:10 AM, Luis R. Rodriguez wrote: > On Tue, May 3, 2016 at 10:07 AM, Luis R. Rodriguez wrote: >> Thanks! Can you confirm if any Android or Brillo builds are already using it? > > Also more importantly, any chance you can provide any technical > reasons why initramfs cannot be used, or it was decided to not use it > on these systems? It should help others in the future as well. In Chrome OS, the kernels are built specifically for the hardware they're going to be on, so an initramfs was seen as a needless additional boot step. Since Chrome OS was heavily optimized for boot speed, it was designed to not need the initramfs at all. This is actually enforced by the read-only boot firmware, so there's no trivial way to _start_ using an initramfs on (existing) Chrome OS devices either. -Kees -- Kees Cook Chrome OS & Brillo Security