On Mon, May 05, 2008 at 11:30:55AM +0100, Alan Cox wrote: > > (5) uart_remove_one_port() is called by serial8250_register_port() > > since ttyS0 is already in use but it is requested to be once removed. > > That means 8250_pnp is taking over and then trying to delete the console, > so its breakage in the serial layer glue. Perhaps Russell has some ideas > as its hard to tell what he intended to happen originally. Looking at the original report, yes, it is (and will) try to delete the console. However, it's doing the best it can to tell the tty layer "oi, this is port going away, don't do anything more with it" by hanging it up. The real question is: why, after we try to hang up a specific port, is the tty layer continuing to use the port... and the answer is that the tty layer exempts the console from the usual hangup processing. IOW, you can not hang up the console port or indeed ever safely unregister it. Other solutions? Well, we could modify it in place but that gets awfully icky and racy with... the console, so we wouldn't actually be solving anything. The only other solution I can think of is to basically deny any change to the console port, so it never disappears, and therefore never becomes owned by PNP, PCI or whatever. Which also means that it'll probably mess up power management of it. I guess broken console PM is more preferable than oopsing peoples machines. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
