From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seewer Philippe Subject: Re: [RFC PATCH] Move actually mounting the root filesystem into its own series of hooks. Date: Wed, 25 Feb 2009 08:25:29 +0100 Message-ID: <49A4F269.3030304@bfh.ch> References: <3188506a1f06de54ee7874fc45261f5c2faf9e79.1235283966.git.victor.lowther@gmail.com> <49A301FF.2090303@redhat.com> <1235434056.28090.28.camel@sentry-no.fnordovax.org> <49A3AB75.1010805@bfh.ch> <1235475578.28090.64.camel@sentry-no.fnordovax.org> <49A3F43F.6000103@bfh.ch> <644FF96C-AAA8-4309-A3C8-B38EA1DE7C45@gmail.com> <49A414CD.8070204@bfh.ch> <20090224185034.GA1834@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090224185034.GA1834-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: initramfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: "" Jeremy Katz wrote: > On Tuesday, February 24 2009, Seewer Philippe said: >> Victor Lowther wrote: >> [snip] >>>> - 'dhclient -nw': Why are you starting the dhclient in daemon mode? >>>> Couldn't that pose problems when dhcp takes ages to acquire an >>>> adress? I mean like, we've ifup'ed all interfaces and are allready in >>>> the mount hooks without an ip. I guess we'd have to have a blocking >>>> mount-script waiting for at least one interface to be really brought >>>> up or spew an error message after a specific time out. >>> I run it in daemon mode so that udev does not have to wait on it. The >>> dhclient-script creates a file when the interface is up, and any mounts >>> that depend on the network can wait for those files to appear. ifup >>> does the same thing with static interfaces. >> I don't like the asynchronousnes of this. This means we have to wait in >> pre-mount or mount until we have at least one interface up without any >> knowledge if another might come up later as well. > > The problem is that the appearance of devices *is* asynchronous and you > have to keep things as event driven. That's why originally everything > was being driven off of udev rules rather than hooks. If you start > trying to do things in hooks and assume synchronous behavior, boot will > be slower and you also can't have, eg, usb devices being used (usb plug > events are always async; anything else is an illusion) That is of course correct. Though in the case of a netboot I'd like to argue that we absolutely need to make sure that networking is correctly set up before trying to mount anything. So making it synchronous makes the whole a lot easier to control. And to be honest, with netboot I don't think boot time matters all that much. The bottleneck will always be dhcp and the net itself. Regards, Philippe -- To unsubscribe from this list: send the line "unsubscribe initramfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html