From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754446AbcH3XZW (ORCPT ); Tue, 30 Aug 2016 19:25:22 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:34613 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751258AbcH3XZU (ORCPT ); Tue, 30 Aug 2016 19:25:20 -0400 X-IBM-Helo: d24dlp02.br.ibm.com X-IBM-MailFrom: bauerman@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: Thiago Jung Bauermann To: Mark Rutland Cc: kexec@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, AKASHI Takahiro , Eric Biederman , Dave Young , Vivek Goyal , Baoquan He , David Laight , Michael Ellerman , Benjamin Herrenschmidt , Stewart Smith , Arnd Bergmann , Russell King - ARM Linux , Andrew Morton Subject: Re: [PATCH v2 0/2] extend kexec_file_load system call Date: Tue, 30 Aug 2016 20:25:08 -0300 User-Agent: KMail/4.14.3 (Linux/4.4.0-34-generic; KDE/4.14.13; x86_64; ; ) In-Reply-To: <20160818102112.GB27045@leverpostej> References: <1470956638-3589-1-git-send-email-bauerman@linux.vnet.ibm.com> <20160818102112.GB27045@leverpostej> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16083023-0028-0000-0000-0000013A6904 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16083023-0029-0000-0000-000013F61503 Message-Id: <2408856.dZN5fLyePL@hactar> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-08-30_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1608300223 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Mark, Sorry for taking this long to respond. I've been focusing on getting my kexec_file_load and kexec buffer hand-over series in shape. Am Donnerstag, 18 August 2016, 11:21:13 schrieb Mark Rutland: > On Thu, Aug 11, 2016 at 08:03:56PM -0300, Thiago Jung Bauermann wrote: > > Device tree blob must be passed to a second kernel on DTB-capable > > archs, like powerpc and arm64, but the current kernel interface > > lacks this support. > > > > This patch extends kexec_file_load system call by adding an extra > > argument to this syscall so that an arbitrary number of file descriptors > > can be handed out from user space to the kernel. > > > > See the background [1]. > > > > Please note that the new interface looks quite similar to the current > > system call, but that it won't always mean that it provides the "binary > > compatibility." > > > > [1] http://lists.infradead.org/pipermail/kexec/2016-June/016276.html > > As with the original posting, I have a number of concerns, and I'm > really not keen on this. Thanks for laying out out the reasons for your objection. That's very helpful. > * For typical usecases, I do not believe that this is necessary (at > least for arm64), and generally do not believe that it should be > necessary for a user to manipulate the DTB (much like the user need > not manipulate ACPI tables or other FW data structures). > > Other than (potentially) the case of Linux as a flashed-in bootloader, > I don't see a compelling case for modifying the DTB that could not be > accomplished in-kernel. For that case, if truly necessary, I think > that we can get away with something simpler. Yes, this is the case I am aiming for. I'll experiment with a couple of different approaches and see how well they perform. -- []'s Thiago Jung Bauermann IBM Linux Technology Center