From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752600AbcGMIYX (ORCPT ); Wed, 13 Jul 2016 04:24:23 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:30049 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750883AbcGMIYK (ORCPT ); Wed, 13 Jul 2016 04:24:10 -0400 X-IBM-Helo: d01dlp02.pok.ibm.com X-IBM-MailFrom: stewart@linux.vnet.ibm.com From: Stewart Smith To: Arnd Bergmann , linuxppc-dev@lists.ozlabs.org Cc: Mark Rutland , bhe@redhat.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Vivek Goyal , AKASHI Takahiro , "Eric W. Biederman" , bauerman@linux.vnet.ibm.com, Dave Young , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC 0/3] extend kexec_file_load system call In-Reply-To: <5352106.oQ0Ff9gWJA@wuerfel> References: <20160712014201.11456-1-takahiro.akashi@linaro.org> <20160712145010.GA8447@leverpostej> <20160713023614.GB3222@dhcp-128-65.nay.redhat.com> <5352106.oQ0Ff9gWJA@wuerfel> User-Agent: Notmuch/0.21+24~gbceb651 (http://notmuchmail.org) Emacs/25.0.94.1 (x86_64-redhat-linux-gnu) Date: Wed, 13 Jul 2016 18:23:34 +1000 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16071308-0056-0000-0000-000000C4FE2E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16071308-0057-0000-0000-000004DF0E1B Message-Id: <87k2gqndyx.fsf@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-13_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1607130094 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arnd Bergmann writes: > On Wednesday, July 13, 2016 10:36:14 AM CEST Dave Young wrote: >> On 07/12/16 at 03:50pm, Mark Rutland wrote: >> > On Tue, Jul 12, 2016 at 04:24:10PM +0200, Arnd Bergmann wrote: >> > > On Tuesday, July 12, 2016 10:18:11 AM CEST Vivek Goyal wrote: >> > >> > /proc/devicetree (aka /sys/firmware/devicetree) is a filesystem derived >> > from the raw DTB (which is exposed at /sys/firmware/fdt). >> > >> > The blob that was handed to the kernel at boot time is exposed at >> > /sys/firmware/fdt. >> >> I believe the blob can be read and passed to kexec kernel in kernel code without >> the extra fd. >> >> But consider we can kexec to a different kernel and a different initrd so there >> will be use cases to pass a total different dtb as well. From my understanding >> it is reasonable but yes I think we should think carefully about the design. > > Ok, I can see four interesting use cases here: > > - Using the dtb that the kernel has saved at boot time. Ideally this should not > require an additional step of signing it, since the running kernel already > trusts it. - using current view of the hardware, flattened into a new dtb. This should already be trusted, as it's what we're running now (boot + runtime changes) -- Stewart Smith OPAL Architect, IBM.