On Tue, Feb 10, 2004 at 08:18:34PM +0100, Christophe Saout wrote:

udev maintains a database of already created devices. And sysfs is some
sort of database of really existing devices. The "telling udev to not
create the device and instead create it ourself" is bad. We should be
able to tell udev that it should register and create another device
instead. Perhaps udev should know about compound devices.

I'm not sure but if udev knows about compound devices things get a bit
more complicated. A raid 1 setup would continue to work if one of the
devices is unplugged, a raid 0 setup fails to work if one device is
missing. Probably the device should be deleted only when both hard disks
are removed. Also it should be created if only one hard disk gets
plugged in. But on bootup if some script tells udev that one hard disk
is there and some seconds later that the second is also there the tool
shouldn't assume the raid has failed after seeing the first event.

Should we Cc an udev developer for an opinion?

udev can either ignore compound devices with a rule that matches the
dm-* block devices, or it can do something about them.

I really don't think udev in and of itself needs to know anything
special about these kinds of devices, as it will be glad to kick off
other programs for you if you want it to.

thanks,

greg k-h