Re: Runaway loop with the current git.

From: Kay Sievers
Date: Sun Dec 07 2008 - 12:40:02 EST

On Sun, Dec 7, 2008 at 18:28, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:
>> > /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 ?

Not sure, if you understand the real problem. A kernel forked binary
is allowed to access /dev/console, but it triggers a kernel bug.

> 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.

Utter nonsense. Exactly when the driver is available shortly later,
the console will work. If it's not backed by a driver, it should not
try to load it, it will never get any driver loaded by opening it. The
kernel must handle that.

> The correct sequence is
> Open device
> Kernel issues hotplug message
> Hotplug script loads drivers to policy

Nonsense. The kernel calls /sbin/modprobe directly, no hotplug involved.

> The problem case you have due to initrd bugs is
> Open device
> Kernel issues hotplug message
> Hotplug script opens same device (BUG)

The kernel calls modprobe for something, modprobe tries to log an
error, and the kernel calls modprobe again. Bug! No hotplug involved.

> Kernel issues hotplug message
> .....
> Kernel detects this is stuck
> Kernel replies with -ENODEV/-ENXIO to try
> and rescue itself from buggy initrd scripts

Totally wrong, It never was that way.

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

Please update your idea of hotplug and the kernel module loader, you
are on the totally wrong track.

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