Here's a weird one, on Knoppix 5.1.1.

When booting from CD, everything works fine.

When booting from USB, however, udev fails.

Both booting methods have no trouble finding the Knoppix device, and the Knoppix compressed image file. I compared the Knoppix image file on both devices and it's an exact match, so I can rule out corrupted media.

When udev fails, it doesn't hang completely. Instead, it just prints "Starting udev hotplug hardware detection... Failed" in red, after a few seconds.

Another error message appears:

open /dev/mem: No such file or directory (this appears 6 times)

Looks like the /dev directory is hosed, because of udev's failure. X doesn't start. Knoppix tries several X servers, and they all fail. The system then cleanly shuts itself down, and I'm left with no choice but to reboot again.

So, I booted again with the "noudev" cheat code.

This works, and I can get into a working X session.

However, there's a problem: I can't use any terminals. A popup window appears, about being unable to open a pty (pseudoterminal device). Looks like something's hosed. I checked the /dev directory, and all the device files are there, though, including the all-important /dev/ptmx file.

There's other weird failures as well, when trying other programs. It still detects my USB keyboard and USB mouse just fine, though, so I can use the X session. Without terminal access, Knoppix is kind of useless as a rescue disk for me.

The strange thing is that *older* versions of Knoppix worked better for this! Knoppix 5.0 didn't have this glitch at all.

Does anybody know why udev would work fine from CD, but not work when booted from USB? Is there a fix for this?