[plug] 2.6 Kernels, Upgrading from kernel with devfs, to kernel without

[Ian Kent]

On Wed, 3 Aug 2005, Timothy White wrote:

> Hi. I've noticed via googling that this problem has hit a lot of
> people hard. Basically, when they use a kernel with devfs compiled in,
> even if they are using udev, then goto using no devfs and just udev,
> they can't boot.
> You get a Kernel Panic similar to this.
> ---
> VFS: Cannot open root device "hda7" or unknown-block(3,7)
> Please append a correct "root=" option
> Kernel panic: VFS: Unable to mount root fs on unknown-block(3,7)
> ---
> This has just hit me and from what I can see, the problem appears to
> be that /dev/ is empty because devfs isn't filing it with dev nodes,
> and udev is obviously not running yet.
> So what's the solution? If we start creating nodes in there then that
> defeats the purpose of udev. If we compile in devfs then it can never
> be removed from the kernel (it is obsolete) as udev can't work without
> it unless we have static nodes!
> 
> So what is the solution? I really don't want to recompile with devfs
> just so I can boot. There should be a better way otherwise devfs isn't
> really obsolete. I hope someone has the answer.

Why not just mknod the devices you need to boot until you can find out how 
it is meant to be solved.

Perhap you'll need a few devices.
There should be a script to create various groups of device files called
"MAKEDEV" (I think) on your system.

Ian