[Wylug-help] USB Flash: device numbers, filenames and grub

[Dave Fisher]

On Fri, Jan 26, 2007 at 07:07:23PM +0000, Anne Wilson wrote:
> Dave, I've been looking into usb device naming, though not with booting in 
> mind, so I don't know how much this helps.
> 
> As far as I can make out, there's no way that you can alter the order that 
> they are mounted.  What you can do, is make /dev/whatevers that point to the 
> device you want.  For instance, I have /dev/webcam, that sometimes points 
> to /dev/video0 and sometimes to /dev/video1.  This is set up by using the 
> information from udevinfo.  If you think this may solve at least some of your 
> problems, there's a great tutorial at 
> www.reactivated.net/writing_udev_rules.html
> 
> Anne

Thanks Anne,

That reference helped answer some questions I've had about udev for
quite some time.

It certainly enables one to mount an device in a consistent place,
regardless of the kernel's default name, by creating a symlink
'on-the-fly'.

Unfortunately, as you guessed, it doesn't necessarily solve the problem
of booting.

From what my experiments indicate, the personal udev rules are not yet
applied at the time when the kernel needs to mount the root filesystem
(or at least, when the kernel needs to know the filesystem device
address).

One possibility that occurred to me was that the suggested personal
rules file (/etc/udev/rules.d/10-local.rules) might not be loaded
sufficiently early for its rules to apply.

Even if this were true, I'm not sure whether it is feasible to load it
earlier, and in a safe/reliable way.

Does anyone know something about that?

Dave