autoloading sg driver during boot

Paul Howarth paul at
Thu Apr 14 07:25:20 UTC 2005

On Wed, 2005-04-13 at 15:48 -0500, Aleksandar Milivojevic wrote:
> Probably something trivial, but can't seem to find solution (other than 
> placing "modprobe sg" in /etc/rc.local).
> I attempted something like this in modprobe.conf:
> alias char-major-21 sg
> (and also char-major-21-* variant)
> The problem is, there are no /dev/sg* entries in /dev when machine 
> boots.  They are created by udev when "sg" driver loads.  Chicken and 
> egg problem.  Kind of.  So the above lien in modprobe.conf does not 
> really work.
> So....  the question is, is there any way to instruct udev to create 
> /dev/sg* nodes (so that applications can access it and trigger auto 
> loading of sg driver)?  Or instruct system to autoload sg module during 
> boot if there are any SCSI devices, which would trigger udev to create 
> /dev/sg* nodes?  Other than placing "modprobe sg" in /etc/rc.local.

I have a SCSI scanner that uses the sg module; I wrote a custom udev
rule to identify the scanner when the SCSI adapter module detects it,
and that then creates the /dev/sg* entry for it. Can't you do something
like that?

Paul Howarth <paul at>

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