From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Date: Wed, 07 Jun 2006 03:46:07 +0000 Subject: Re: hotplugging on an embedded system under 2.6.17(-rcX) Message-Id: <20060607034607.GA7047@kroah.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org On Tue, Jun 06, 2006 at 11:56:33AM +0200, Guennadi Liakhovetski wrote: > Hi all, > > We are building an embedded system based on oe / bitbaker distro and > 2.6.17(-rc5) kernel. And we'd like to use hotplug on it. Hotplug in a > generic sense, not as _the_ /proc/sys/kernel/hotplug = /sbin/hotplug > thing. And this is my first embedded 2.6 project with hotplug... Why do you want to use hotplug? Seriously, if you don't need it I wouldn't just add it for the fun of it. What do you want to accomplish? automatic loading of modules? network connections bring up/down? udev dynamic and persistant device nodes? All of this needs to be determined before you grab a desktop version of the udev and hotplug packages. > First I was pretty much unaware of the way udev / hotplug co-exist now, so > we just installed _the_ "hotplug" package in the same way we were doing > under 2.4 and then we noticed that the boot-time is VERY long, upon closer > investigation it turned out to be the hotplug script that was using up > most of that time being started multiple times on each modprobe. What "hotplug package" did you use? > Now, I've read that now the actual "hotplpug" package is deprecated and > superseded by the udev (from kernel 2.6.15). But one requires a pretty > modern version of udev to really fully replace "hotplug" and best > co-operate with the kernel. First question - starting from which version > of udev is advised for 2.6.15+ kernels? The latest. > Secondly, the version of udev we have from oe is 071. That's quite old, why are you using that version? I would not recommend it. > If I just install it I see the udevd is started, it even dynamically > manages / creates device nodes, and I can see with strace that it also > receives all modprobe / rmmod events from the kernel, but, I suspect > it is not quite properly configured yet, e.g., when I plug in a USB > keyboard usbhid doesn't get loaded. Ok, I can read docs, install the > latest version of udev, configure it, but before I do all that - will > it be _much_ faster than the hotplug? If not - we'll have to look for > another solution... It is much faster than hotplug, but it all comes down to what your udev rules are doing. What are they doing? > Are there any ready embedded fast hotplug solutions? Will it be faster if > one compiles most stuff in the kernel? Our main problem is the startup > time when about 10-20 kernel modules get loaded... Do you need 20 modules? Why? thanks, greg k-h _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel