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From: Lennart Poettering <lennart@poettering.net>
To: "Zbigniew Jędrzejewski-Szmek" <zbyszek@in.waw.pl>
Cc: devicetree <devicetree@vger.kernel.org>,
	systemd-devel@lists.freedesktop.org,
	"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>,
	Hans de Goede <hdegoede@redhat.com>,
	Mark Brown <broonie@kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: Making udev emit a signal when it is done loading modules
Date: Wed, 28 Jan 2015 02:38:52 +0100	[thread overview]
Message-ID: <20150128013852.GA8177@gardel-login> (raw)
In-Reply-To: <20150117160319.GO18247@in.waw.pl>

On Sat, 17.01.15 17:03, Zbigniew Jędrzejewski-Szmek (zbyszek@in.waw.pl) wrote:

> On Sat, Jan 17, 2015 at 09:44:00AM +0100, Hans de Goede wrote:
> > We would like
> > udev to emit a signal (ABI to be discussed) when it is done
> > trying to load modules for everything which was already enumerated
> > when it starts, iow when there are no new device events pending
> > anymore when udev does its initial hotplug replay.
> I think you can just create a unit like:
> 
> # disable-new-hardware.service
> [Unit]
> After=systemd-udev-settle.service systemd-modules-load.service
> Wants=systemd-udev-settle.service
> 
> [Service]
> Type=oneshot
> RemainAfterExit=yes
> ExecStart=/usr/local/bin/ping-the-kernel
> 
> > So the question to you is would you be willing to include such
> > functionality in udev?
> I don't think udevd has enough knowledge. But a systemd unit like
> the one above should work.

To clarify this: if people do this, then this pulls in
systemd-udev-settle.service, which slows down boot. Every service that
does that is hence a majour source of slowness. 

It's a hack to use this, not a solution. 

Lennart

-- 
Lennart Poettering, Red Hat
_______________________________________________
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systemd-devel@lists.freedesktop.org
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WARNING: multiple messages have this Message-ID (diff)
From: lennart@poettering.net (Lennart Poettering)
To: linux-arm-kernel@lists.infradead.org
Subject: [systemd-devel] Making udev emit a signal when it is done loading modules
Date: Wed, 28 Jan 2015 02:38:52 +0100	[thread overview]
Message-ID: <20150128013852.GA8177@gardel-login> (raw)
In-Reply-To: <20150117160319.GO18247@in.waw.pl>

On Sat, 17.01.15 17:03, Zbigniew J?drzejewski-Szmek (zbyszek at in.waw.pl) wrote:

> On Sat, Jan 17, 2015 at 09:44:00AM +0100, Hans de Goede wrote:
> > We would like
> > udev to emit a signal (ABI to be discussed) when it is done
> > trying to load modules for everything which was already enumerated
> > when it starts, iow when there are no new device events pending
> > anymore when udev does its initial hotplug replay.
> I think you can just create a unit like:
> 
> # disable-new-hardware.service
> [Unit]
> After=systemd-udev-settle.service systemd-modules-load.service
> Wants=systemd-udev-settle.service
> 
> [Service]
> Type=oneshot
> RemainAfterExit=yes
> ExecStart=/usr/local/bin/ping-the-kernel
> 
> > So the question to you is would you be willing to include such
> > functionality in udev?
> I don't think udevd has enough knowledge. But a systemd unit like
> the one above should work.

To clarify this: if people do this, then this pulls in
systemd-udev-settle.service, which slows down boot. Every service that
does that is hence a majour source of slowness. 

It's a hack to use this, not a solution. 

Lennart

-- 
Lennart Poettering, Red Hat

  parent reply	other threads:[~2015-01-28  1:38 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-17  8:44 Making udev emit a signal when it is done loading modules Hans de Goede
2015-01-17  8:44 ` Hans de Goede
2015-01-17 13:56 ` Greg KH
2015-01-17 13:56   ` [systemd-devel] " Greg KH
2015-01-17 14:12   ` Mark Brown
2015-01-17 14:12     ` Mark Brown
2015-01-17 14:52   ` Hans de Goede
2015-01-17 14:52     ` [systemd-devel] " Hans de Goede
     [not found]   ` <20150117135630.GA25585-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2015-01-17 15:23     ` jonsmirl-Re5JQEeQqe8AvxtiuMwx3w
2015-01-17 15:23       ` jonsmirl at gmail.com
2015-01-17 16:03 ` David Herrmann
2015-01-17 16:03   ` David Herrmann
2015-01-17 16:03 ` Zbigniew Jędrzejewski-Szmek
2015-01-17 16:03   ` [systemd-devel] " Zbigniew Jędrzejewski-Szmek
2015-01-17 16:45   ` Kay Sievers
2015-01-17 16:45     ` Kay Sievers
2015-01-28  1:38   ` Lennart Poettering [this message]
2015-01-28  1:38     ` Lennart Poettering
2015-02-11  5:28     ` Mark Brown
2015-02-11  5:28       ` Mark Brown

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