Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753778AbbD2P2F (ORCPT ); Wed, 29 Apr 2015 11:28:05 -0400 Received: from mondschein.lichtvoll.de ([194.150.191.11]:39302 "EHLO mail.lichtvoll.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753753AbbD2P2C convert rfc822-to-8bit (ORCPT ); Wed, 29 Apr 2015 11:28:02 -0400 From: Martin Steigerwald To: Harald Hoyer Cc: John Stoffel , Havoc Pennington , "Theodore Ts'o" , Linus Torvalds , Andy Lutomirski , Lukasz Skalski , Greg Kroah-Hartman , Andrew Morton , Arnd Bergmann , "Eric W. Biederman" , One Thousand Gnomes , Tom Gundersen , Jiri Kosina , "linux-kernel@vger.kernel.org" , Daniel Mack , David Herrmann , Djalal Harouni Subject: Re: [GIT PULL] kdbus for 4.1-rc1 Date: Wed, 29 Apr 2015 17:27:59 +0200 Message-ID: <1608909.Hzt9NDh2yO@merkaba> User-Agent: KMail/4.14.7 (Linux/4.0.0-tp520-btrfs-trim+; KDE/4.14.2; x86_64; git-38b5d90; 2015-04-16) In-Reply-To: <5540D2F9.2010704@redhat.com> References: <20150423163616.GA10874@kroah.com> <21824.5086.446831.189915@quad.stoffel.home> <5540D2F9.2010704@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="iso-8859-1" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1765 Lines: 36 Am Mittwoch, 29. April 2015, 14:47:53 schrieb Harald Hoyer: > We really don't want the IPC mechanism to be in a flux state. All tools > have to fallback to a non-standard mechanism in that case. > > If I have to pull in a dbus daemon in the initramfs, we still have the > chicken and egg problem for PID 1 talking to the logging daemon and > starting dbus. > systemd cannot talk to journald via dbus unless dbus-daemon is started, > dbus cannot log anything on startup, if journald is not running, etc... Do I get this right that it is basically a userspace *design* decision that you use as a reason to have kdbus inside the kernel? Is it really necessary to use DBUS for talking to journald? And does it really matter that much if any message before starting up dbus do not appear in the log? /proc/kmsg is a ring buffer, it can still be copied over later. I remember this kind of reason not not having cgroup management in a separate process, but these are both in userspace. "We have done it this way in userspace, thus this needs to be in kernel" doesn?t sound quite convincing to me as an argument for having dbus inside the kernel. Userspace uses the API the kernel and glibc provide, yes, it makes sense to look at what userspace needs, but designing some things in userspace and then requiring support for these design decisions in the kernel just doesn?t sound quite right to me. -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/