[experimental] scsiinfo driver

[experimental] scsiinfo driver

[Douglas Gilbert]

Last month there were some discussions on this list about hotplugging
(and unplugging) SCSI devices. That was mainly in the context of various
pseudo drivers such as sbp2_1394, usb/mass_storage and usb/microtek.

As was pointed out at the time, various changes would probably be
required to the SCSI subsystem. As an incremental approach to the
problem an experimental upper level driver is available for lk 2.4.2:
http://www.torque.net/scsi/scsiinfo.html

Essentially this driver monitors device attaches and detaches. If
CONFIG_HOTPLUG has been set then the /sbin/hotplug mechanism is
invoked. In any case lists of attached and detached devices plus a
host list are available via ioctls.

At this stage there is very little documentation. Look at the ioctl
test program (si_test.c), the header file (include/scsi/scsiinfo.h)
and the si_call_policy() function in the driver to see the names of
the provided environment variables.

I look forward to suggestions :-)

Doug Gilbert

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Re: [experimental] scsiinfo driver

[David Brownell]

Looks like a promising direction, especially if (as you'd
suggested offline) very similar models can work for IDE.

What would the job of /etc/hotplug/scsi.agent be?  I'm not
quite clear -- modprobe "sd" or "sg"?  Mount partitions
in the appropriate filesystem locations?

(I said "script", but of course that's optional; some logic
to figure out a right mount point might want to call into
compiled libraries.)

- Dave




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Re: [experimental] scsiinfo driver

[Bill Nottingham]

David Brownell (david-b@pacbell.net) said: 
> Looks like a promising direction, especially if (as you'd
> suggested offline) very similar models can work for IDE.
> 
> What would the job of /etc/hotplug/scsi.agent be?  I'm not
> quite clear -- modprobe "sd" or "sg"?  Mount partitions
> in the appropriate filesystem locations?

- modprobe whatever scsi modules are appropriate
- create appropriate mount points & entries in /etc/fstab
- signal whatever thing is creating desktop icons to add new ones
  (if it's not watching /etc/fstab)

We've got something here that we're using to do the second
of these; it is currently getting called on pcmcia/usb events
for storage things, but it runs into the problem that requires
this SCSI event system (race between device creation, userland
notification, and partition table reading...)

Bill

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Re: [experimental] scsiinfo driver

[Douglas Gilbert]

Bill Nottingham wrote:
> 
> David Brownell (david-b@pacbell.net) said:
> > Looks like a promising direction, especially if (as you'd
> > suggested offline) very similar models can work for IDE.
> >
> > What would the job of /etc/hotplug/scsi.agent be?  I'm not
> > quite clear -- modprobe "sd" or "sg"?  Mount partitions
> > in the appropriate filesystem locations?
> 
> - modprobe whatever scsi modules are appropriate
> - create appropriate mount points & entries in /etc/fstab
> - signal whatever thing is creating desktop icons to add new ones
>   (if it's not watching /etc/fstab)
> 
> We've got something here that we're using to do the second
> of these; it is currently getting called on pcmcia/usb events
> for storage things, but it runs into the problem that requires
> this SCSI event system (race between device creation, userland
> notification, and partition table reading...)

I have added a simple scsi.agent script that modprobes
the various scsi upper level drivers (e.g. sr and st) based
on the scsi type of the newly added device. See:
http://www.torque.net/scsi/scsiinfo.html

Can anyone think of a better name than "scsiinfo" as H.
Peter Anvin doesn't like it?

Doug Gilbert


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