Re: Asynchronous scsi scanning, version 9

[Matthew Wilcox <matthew@wil.cx>]

On Mon, Jun 26, 2006 at 02:08:25PM -0700, Matthew Dharm wrote:
> On Mon, Jun 26, 2006 at 09:18:28AM -0600, Matthew Wilcox wrote:
> > Do these devices stick to occupying only target IDs from 0-7?  If not,
> > you may wish to increase ->max_id for those devices.  I think it'd be worth
> > exporting scsi_scan_channel() from the midlayer (and rearranging it to have
> > __scsi_scan_channel() as was done with __scsi_scan_target) for USB's benefit.
> 
> These support target IDs to up 15.  But I see the point of limiting
> ->max_id for devices which do not have the SCM_MULT_TARG flag set.

Ever tried that?  ;-)

drivers/scsi/hosts.c sets max_id to 8 in scsi_host_alloc().  I don't see
anything in USB setting max_id to 16.

> > It's definitely possible to remove individual targets dynamically now;
> > Fibre Channel has sorted that out (and will complain loudly if it breaks).
> > The scsi core doesn't really have a channel object; channel is just an integer 
> > that describes a path to a target.  So I think there should be no problem in
> > converting USB to have one host and many channels.
> 
> Interesting.
> 
> What's the limit on the number of channels you can have?

Just an unsigned int, I think.

> How do I set up multiple channels in code?

Increase shost->max_channel each time you want to create a new one.
Then pass it to scsi_scan_target().