linux-kernel - Re: Runaway loop with the current git.

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Message-ID: <20081207172855.55fee78f@lxorguk.ukuu.org.uk>
Date:	Sun, 7 Dec 2008 17:28:55 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	"Kay Sievers" <kay.sievers@...y.org>
Cc:	"Evgeniy Polyakov" <zbr@...emap.net>,
	"Herbert Xu" <herbert@...dor.apana.org.au>,
	linux-kernel@...r.kernel.org,
	"Linux Crypto Mailing List" <linux-crypto@...r.kernel.org>
Subject: Re: Runaway loop with the current git.

> > /dev/console is a logical mapping to a device which may well be
> > different, loaded after PCI is initialised and dependant on PCI.
> 
> So wrong. If no driver is associated, like early, in that case, we
> must return -ENODEV, instead of calling modprobe in a loop. It's a
> built-in device, and it's easy to fix.

You've clearly no idea how initrd even works have you ? If it just
returned -ENODEV you wouldn't be able to open the console and you
wouldn't trigger the loading of the module to get the console running. So
you've now completely buggered the boot process.

The correct sequence is

	Open device
		Kernel issues hotplug message
			Hotplug script loads drivers to policy


The problem case you have due to initrd bugs is

	Open device
		Kernel issues hotplug message
			Hotplug script opens same device (BUG)
				Kernel issues hotplug message
				.....
				Kernel detects this is stuck
				Kernel replies with -ENODEV/-ENXIO to try
and rescue itself from buggy initrd scripts

That is how it has worked since we first had script based module
requesting which is some years now.

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