Udev issues in today's coming rawhide

Arjan van de Ven arjan at fenrus.demon.nl
Thu Mar 2 15:25:50 UTC 2006


On Thu, 2006-03-02 at 10:13 -0500, John Thacker wrote:
> On Thu, Mar 02, 2006 at 03:39:21PM +0100, Arjan van de Ven wrote:
> > better would be to use UUID's, or at least vendor identification strings
> > etc from the device. We need to NOT tie these device names to underlying
> > accidental device numbers. That is a major major step back.
> 
> Wouldn't vendor identification strings, at least by themselves, still 
> cause problems when people have two identical model devices?  That's
> fairly rare for CDROM devices but not unheard of.  From what I understand
> of the output of udevinfo, it doesn't look like a UUID is exported
> as an environment variable the way that the vendor id strings are.
> I don't claim to understand everything, though, and of course it could
> be changed as well.
> 
> My understanding anyway is that the old method still somewhat depended
> the underlying accidental device numbers, at least when it came to
> deciding which was /dev/cdrom and which was /dev/cdrom1.

but so does the new one! For example on one of my test boxes, it depends
on if I have a USB stick inserted.. if it is at boot, sda is my usb
stick and sdb is my sata disk, and sdc my cd writer.
if it's not, sda is my disk and sdb my cd writer.
Now add USB cd writers to the mix and it's clear that such device names
are not persistent at all and utterly useless for identification.

(and since USB goes via my kvm, this device order is potentially
different each time I switch my kvm to this machine)

while you can have 2 of the same type, the problem is at least less than
before, not bigger than before as is the case with the proposed
"solution".





More information about the devel mailing list