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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 62AA7C43331 for ; Fri, 6 Sep 2019 15:07:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40AE02067D for ; Fri, 6 Sep 2019 15:07:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403855AbfIFPHa (ORCPT ); Fri, 6 Sep 2019 11:07:30 -0400 Received: from mx2.suse.de ([195.135.220.15]:38120 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730480AbfIFPH3 (ORCPT ); Fri, 6 Sep 2019 11:07:29 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 59AACAC67; Fri, 6 Sep 2019 15:07:28 +0000 (UTC) Date: Fri, 6 Sep 2019 17:07:37 +0200 From: Jean Delvare To: Greg Kroah-Hartman Cc: Arnd Bergmann , Thomas , LKML Subject: Re: /dev/mem and secure boot Message-ID: <20190906170737.1a00178c@endymion> In-Reply-To: <20190906121510.GA17328@kroah.com> References: <20190906130221.0b47a565@endymion> <20190906121510.GA17328@kroah.com> Organization: SUSE Linux X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 6 Sep 2019 14:15:10 +0200, Greg Kroah-Hartman wrote: > On Fri, Sep 06, 2019 at 01:02:21PM +0200, Jean Delvare wrote: > > I've been bitten recently by mcelog not working on machines started in > > secure boot mode. mcelog tries to read DMI information from /dev/mem > > and fails to open it. > > What do you mean by "secure boot"? Is this matthew's patchset that > restricts /dev/mem/ or something else? I mean that early in the kernel log is: Secure boot enabled and kernel locked down > > This made me wonder: if not even root can read /dev/mem (nor, I > > suppose, /dev/kmem and /dev/port) in secure boot mode, why are we > > creating these device nodes at all in the first place? Can't we detect > > that we are in secure boot mode and skip that step, and reap the rewards > > (faster boot, lower memory footprint and less confusion)? > > Sure, feel free to not register it at all if the mode is enabled. > > thanks, > > greg k-h -- Jean Delvare SUSE L3 Support