udev: distinguish between USB floppy & memory stick

jrfk2 · 02-12-2007, 02:01 PM

Writing udev rules and need to distinguish between floppy devices and USB memory sticks ..

Sifting thru all the udevinfo stuff I see that sticks have SYSFS{dev}=="8:17" and floppys have "8:32" ..

As best I can find out from surfin the net those numbers are major/minor numbers I *think* ... but haven't found anything to explain what they mean in detail and if I can count on them for those specific devices on different h/w, etc...

Or if there is better SYSFS info to use ..

Appreciate any pointers ...

dracolich · 02-12-2007, 02:37 PM

When writing my rules I use SYSFS{Product}="Product Name". It's almost always the name that can be found in dmesg. My USB floppy drive's product is "MISTSUMI FLOPPY" and my flash drives are "JUMPDRIVE TRIO" and "SanDisk Cruzer Micro" et al. I also used the rules to create symlinks automatically for easier fstab entries and mounting.

jrfk2 · 02-13-2007, 07:03 AM

Yep, I was going to use SYSFS{product} as well but then found different USB Keys report different stuff, and I was hoping (praying? ;-)) there was some value in all the udevinfo stuff that identified the type of device generically ..

I did since find some more details on major/minor and I don't think they can be used to identify the type of device, so I'm still kinda stuck ..

SciYro · 02-13-2007, 09:18 AM

The major/minor numbers are completely arbitrary, but they should be the same across computers (or else /dev would have had serious problems way back when you had to manually create /dev files to add new hardware, it should be fine, but like i said, the numbers are arbitrary, you should really find another way if you can.

jrfk2 · 02-15-2007, 09:07 AM

I also noticed that the USB floppy reports SYSFS{interface}=="FLOPPY" but the memory stick doesn't report that SYS{interface} at all. Is there any way to write rules to take advantage of that?