From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3sP4Pb1ydtzDqXr for ; Wed, 31 Aug 2016 09:25:23 +1000 (AEST) Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u7UNNYXd107633 for ; Tue, 30 Aug 2016 19:25:20 -0400 Received: from e24smtp01.br.ibm.com (e24smtp01.br.ibm.com [32.104.18.85]) by mx0a-001b2d01.pphosted.com with ESMTP id 25536bfnww-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 30 Aug 2016 19:25:20 -0400 Received: from localhost by e24smtp01.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 30 Aug 2016 20:25:18 -0300 Received: from d24relay03.br.ibm.com (d24relay03.br.ibm.com [9.13.184.25]) by d24dlp02.br.ibm.com (Postfix) with ESMTP id 3D1421DC006D for ; Tue, 30 Aug 2016 19:25:05 -0400 (EDT) Received: from d24av05.br.ibm.com (d24av05.br.ibm.com [9.18.232.44]) by d24relay03.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u7UNPEd723462354 for ; Tue, 30 Aug 2016 20:25:14 -0300 Received: from d24av05.br.ibm.com (localhost [127.0.0.1]) by d24av05.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u7UNPCGJ007097 for ; Tue, 30 Aug 2016 20:25:14 -0300 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 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-Type: text/plain; charset="us-ascii" Message-Id: <2408856.dZN5fLyePL@hactar> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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