From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757924AbcGKIPH (ORCPT ); Mon, 11 Jul 2016 04:15:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44868 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753159AbcGKIPB (ORCPT ); Mon, 11 Jul 2016 04:15:01 -0400 Date: Mon, 11 Jul 2016 16:14:52 +0800 From: Dave Young To: AKASHI Takahiro , Thiago Jung Bauermann , kexec@lists.infradead.org, ebiederm@xmission.com, bhe@redhat.com, vgoyal@redhat.com, will.deacon@arm.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [RFC] arm64: kexec_file_load support Message-ID: <20160711081452.GA20771@dhcp-128-65.nay.redhat.com> References: <20160701051111.GL20774@linaro.org> <20160705080355.GQ20774@linaro.org> <20160707061245.GA18459@dhcp-128-65.nay.redhat.com> <11139482.zLvCKVycQr@hactar> <20160711071934.GZ20774@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160711071934.GZ20774@linaro.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 11 Jul 2016 08:15:00 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/11/16 at 04:19pm, AKASHI Takahiro wrote: > On Fri, Jul 08, 2016 at 11:48:44AM -0300, Thiago Jung Bauermann wrote: > > Am Donnerstag, 07 Juli 2016, 14:12:45 schrieb Dave Young: > > > If so maybe change a bit from your precious mentioned 7 args proposal like > > > below? > > > > > > struct kexec_file_fd { > > > enum kexec_file_type; > > > int fd; > > > } > > > > > > struct kexec_fdset { > > > int nr_fd; > > > struct kexec_file_fd fd[0]; > > > } > > > > > > int kexec_file_load(int kernel_fd, int initrd_fd, > > > unsigned long cmdline_len, const char *cmdline_ptr, > > > unsigned long flags, struct kexec_fdset *extra_fds); > > > > > > Is there a way for the kernel to distinguish whether the process passed 5 or > > 6 arguments? How can it know whether extra_fds is a valid argument or just > > garbage? I think we have to define a new flag KEXEC_FILE_EXTRA_FDS so that > > the process can signal that it is using the new interface. > > Good point. What I had in my mind is "open" system call. > Glibc's implementation of open() checks for the second argument, flags, > to determine whether or not the third argument, mode, is required. > > So our current consensus is that, for the time being, we will extend > the existing system call interface to allow extra file descriptors, > and *if* we really need a different type of parameters in the future, > we will add another system call. Sounds good to me. > > If we all agree, I can post a kernel patch for this change as a RFC. > (I've already verified it with my prototype of kexec_file_load support > on arm64.) > > Thanks, > -Takahiro AKASHI > > > -- > > []'s > > Thiago Jung Bauermann > > IBM Linux Technology Center > > Thanks Dave