From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rich Turner Date: Fri, 14 Jul 2006 16:49:01 +0000 Subject: Re: udevstart v udevtrigger Message-Id: <200607140949.02146.rich@storix.com> List-Id: References: <200607131359.39003.rich@storix.com> In-Reply-To: <200607131359.39003.rich@storix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org what would be the effects of running udevtrigger on a system running a kernel prior to 2.6.15? will it fail and return a non-zero return code? will it lock up the kernel? if running udevtrigger on a pre-2.6.15 kernel causes bad things then i will need to do some kernel level checking before running it. On Thursday 13 July 2006 16:59, Kay Sievers wrote: > On Thu, 2006-07-13 at 15:06 -0700, Rich Turner wrote: > > we use udev when we perform a bare-metal restore of a system from a > > backup (if the system that we created boot media from has it available). > > we use udev to create device nodes in our boot media environment only. > > once the system is rebuilt then the system's original udev support is > > used. > > > > our only support requirement is that the system is running kernel 2.4 or > > later. granted udev requires 2.6 so those systems are the only ones we > > are discussing. > > > > in short: > > we create the system installation boot media and include the following > > udev-related files on the media: > > udev > > udevstart > > udevd (only if udev is not available and there is udevstart) > > /etc/udev/* > > > > we use udev by running udevstart if we have udev command. or we start > > udevd if we do not have the udev command and then run udevstart. this is > > creating all necessary device nodes. > > > > i have not tested this yet, but my thoughts are to add udevtrigger to the > > boot media. then if there is not a udevstart command create a link > > udevstart->udevtrigger. that way i will not have to make changes > > everywhere else in the software where i do run udevstart. > > > > i guess the question is can i treat udevstart and udevtrigger as the same > > command? > > > > will udevtrigger provide me with the same results as udevstart? > > Udevstart, just creates devices nodes and runs completely serialized, it > will return when all currently known kernel devices are found and all > device nodes are created. It will not cause a coldplug run or trigger > kernel module loads for events that got lost during boot. > > Udevtrigger, just asks the kernel to emit all events for all devices > again. Everything runs in parallel, also events to load kerenl modules > are generated. Everything, including device node creation, runs > asynchronously. If needed, you have to wait until the kernel has sent > all events and udev is finished handling the events. That's what > udevsettle is used for. > > Udevstart will hang, if one rule execution blocks, udevtrigger will not > block the whole process. > > Udevtrigger replaced the coldplug logic from the old hotplug package, > udevstart can't do any coldplug. Udevtrigger needs at least kernel > 2.6.15. > > Udevstart and the udev binary are no longer installed by default on > recent systems. > > Kay -- Rich Turner Storix, Inc. 619-543-0200 x113 ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid0709&bid&3057&dat1642 _______________________________________________ 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