mount custom device node (ex: "/dev/mydevice")

Lobinho · 06-16-2010, 04:27 PM

Dear all,

I'm trying to mount a custom device node for each usb port of my pc. For example:
Every pen drive connected to my usb 1-1.2 will be called /dev/usb2 and mounted on /mnt/usb2, on usb 1-1.3 port the device node will be called /dev/usb3 and mounted on /mnt/usb3.

I'm using an embedded linux, the device handler is mdev. Editing mdev.rules I'm able to manage new devices and write special rules for them (on /bin/hotplug.sh I can mount the /dev/udisk device on anywhere I wanna):

Code:

# This will be called after scsi emulation, so the 
# new device (sda1, sdb1 ...) will be managed by /bin/hotplug.sh
mmcblk0p1	0:0	0600	=sdcard */bin/hotplug.sh
sda1		0:0	0600	=udisk * /bin/hotplug.sh

# This is called when pen drive is connected
1-1.*		0:0	0600	@ /home/lobinho/showdevice.sh $MDEV

The problem is that SCSI emulation define to me the name of the device in order of insertion (following an alphabetical sequence):
/dev/sda
/dev/sdb
/dev/sdc
...

Is there anyway to change scsi emulation configurations or code?
I want to call my pen drive on my way (/dev/usb1 instead of /dev/sd*)!

Someone knows any tip or tutorial that will help me?

Thanks in advance!

conman124 · 06-17-2010, 09:34 PM

Well, if your USB drive is at the same /dev/sd* every time (Say, every time you plug it in, it is at /dev/sda) then you can create a symlink. "ln /dev/sda /dev/usb1 -s"

--Connor

Lobinho · 06-18-2010, 08:09 AM

Hi conman124,

I can have more than one usb drive connected at the same time, so I need to know where they came from (usb port 1-1.1, usb port 1-1.2, ... ).

The "/bin/hotplug.sh" script (scsi emulation) runs after the creation of the usb device on /sys/bus/usb, so I'll try to do something to keep reading this dir and show up what's new. Then on the "/bin/hotplug.sh" script I'll use this information.

Bratmon · 06-18-2010, 10:15 AM

This isn't exactly what you're asking, but if it was the same drives every time, couldn't you use /dev/disk/by-uuid ?

Lobinho · 06-19-2010, 12:07 PM

Hi Bratmon,

I think you reefer to something like this: http://blog.bigsmoke.us/2009/02/06/c...ware-with-udev

On my project I'll have a PC with 2 usb ports available. These ports must have exclusive functions:
USB 1 - (1-1.1) - Only for system backup. This port will accept any generic pen drive and will save a data log on it. This function will be automatic.
USB 2 - (1-1.2) - Save/Load configuration. This port will accept any generic pen drive and save or load some configuration files.

There's no user interface program or line cmd. It's like a server with some services running and nobody will access the system. The only communication with the external world is these two usb ports.

The problem starts when some user plugged a pen drive and inside the system I don't know which usb port he is using (usb1 or usb2), so I don't know if I have to save the log file or not.

Thanks anyway!