[CC: list trimmed, since this may no longer be of general interest] On Wed, 22 Apr 2009, David VomLehn wrote: > I'm going to see if I can come up with some sort of concrete proposal for > waiting for hotpluggable boot devices. I'd appreciate it if you could think > about how to implement the USB-specific part of this. Once we have something > that makes sense, and works, we can go back and pick up the details for > the console, IP autoconfig, and anything else that someone might need done. Whatever you come up with, it should operate on a per-subsystem basis, perhaps together with an additional "all subsystems are done with their boot probing" mechanism. (USB disk drives will still be a problem... I'm going to punt on them for now.) Would it be sufficient to have a "number of pending probes" counter together with a waitqueue? Your console routine could first wait for all the async stuff to end, so that all the USB host controllers had been registered, and then wait (on the new waitqueue) for the counter to go to 0. The hub driver would maintain the counter and signal the waitqueue whenever the counter was decremented to 0. Is it safe to say that we don't have to worry about udev or other userspace hotplug mechanisms? After all, we are talking about things that happen before the first userspace process is set up. And if we had to wait for drivers to be modprobed into the kernel, we'd again be facing unpredictable delays. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
