Help - can Linux SCSI sub-system add newly-attached devices to /dev on the fly?

Help - can Linux SCSI sub-system add newly-attached devices to /dev on the fly?

[Lee Xing]

Hi,

Does any one know if there is a function low-level driver can invoke to notice
mid-layer the changes on the attached devices?  Suppose we hot plug-in or 
pull-off a disk, can low-level driver send a notice to mid-layer and let it
re-scan the bus and add a new sd/sg to /dev?

I was told we could run "echo scsi add-single-device h c t l > /proc/scsi/scsi" 
(where "h c t l" are host_id, channel_id, target_id and lun_id) from user space 
to add a newly-attached device to mid-layer.  Is it the only way (besides reboot)
to add new devices to mid-layer on the fly?

Mid-layer in lk 2.6 defines two functions, scsi_add_device() and scsi_add_host(),
that can be called by low-level drivers based on the document.  I'm not familiar 
with lk2.6.  Can low-level drivers in lk2.6 call scsi_add_device( ) to add 
newly-attached disks to mid-layer on the fly?  Does lk2.4 provide a similar 
function to scsi_add_device( ) in lk2.6?

Thanks,


Lee

Re: Help - can Linux SCSI sub-system add newly-attached devices to /dev on the fly?

[Christoph Hellwig]

On Thu, May 20, 2004 at 11:58:21AM -0500, Lee Xing wrote:
> Mid-layer in lk 2.6 defines two functions, scsi_add_device() and scsi_add_host(),
> that can be called by low-level drivers based on the document.  I'm not familiar 
> with lk2.6.  Can low-level drivers in lk2.6 call scsi_add_device( ) to add 
> newly-attached disks to mid-layer on the fly?

Yes.  For an example take a look at drivers/ieee1394/sbp2.c.

> Does lk2.4 provide a similar 
> function to scsi_add_device( ) in lk2.6?

No.