Date: Wed, 29 Apr 2015 09:36:46 -0700 (PDT)
From: David Lang <david@lang.hm>
To: Martin Steigerwald <martin@lichtvoll.de>
cc: Harald Hoyer <harald@redhat.com>, John Stoffel <john@stoffel.org>,
        Havoc Pennington <hp@pobox.com>, "Theodore Ts'o" <tytso@mit.edu>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Lukasz Skalski <l.skalski@samsung.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Tom Gundersen <teg@jklm.no>, Jiri Kosina <jkosina@suse.cz>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Daniel Mack <daniel@zonque.org>,
        David Herrmann <dh.herrmann@gmail.com>,
        Djalal Harouni <tixxdz@opendz.org>
Subject: Re: [GIT PULL] kdbus for 4.1-rc1
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References: <20150423163616.GA10874@kroah.com> <21824.5086.446831.189915@quad.stoffel.home> <5540D2F9.2010704@redhat.com> <1608909.Hzt9NDh2yO@merkaba>
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On Wed, 29 Apr 2015, Martin Steigerwald wrote:

> 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've been getting the early boot messages in my logs for decades (assuming the 
system doesn't fail before the syslog daemon is started). It sometimes has 
required setting a larger than default ringbuffer in the kernel, but that's easy 
enough to do.

David Lang
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