Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753479AbdDGHFm convert rfc822-to-8bit (ORCPT ); Fri, 7 Apr 2017 03:05:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54734 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752775AbdDGHFe (ORCPT ); Fri, 7 Apr 2017 03:05:34 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com CE5DB85363 Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=dhowells@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com CE5DB85363 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20170407063107.GA10451@dhcp-128-65.nay.redhat.com> References: <20170407063107.GA10451@dhcp-128-65.nay.redhat.com> <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> <149142341772.5101.12366553346604485034.stgit@warthog.procyon.org.uk> To: Dave Young Cc: dhowells@redhat.com, "Rafael J. Wysocki" , Linux Kernel Mailing List , gnomes@lxorguk.ukuu.org.uk, linux-efi@vger.kernel.org, Josh Boyer , Greg Kroah-Hartman , ACPI Devel Maling List , linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, matthew.garrett@nebula.com Subject: Re: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <21359.1491548727.1@warthog.procyon.org.uk> Content-Transfer-Encoding: 8BIT Date: Fri, 07 Apr 2017 08:05:27 +0100 Message-ID: <21360.1491548727@warthog.procyon.org.uk> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 07 Apr 2017 07:05:34 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 770 Lines: 21 Dave Young wrote: > > > This option allows userspace to pass the RSDP address to the kernel, which > > > makes it possible for a user to circumvent any restrictions imposed on > > > loading modules. Ignore the option when the kernel is locked down. > > > > I'm not really sure here. > > > > What exactly is the mechanism? > > Actually this acpi_rsdp param is created for EFI kexec reboot in old > days when we had not supported persistent efi vm space across kexec > reboot. At that time kexec reboot runs as noefi mode, it can not find > the acpi root table thus kernel will hang early. > > Now kexec can support EFI boot so this param is not necessary for most > user unless they still use efi=old_map. Is this patch now unnecessary? David