Re: Warning: about not setting max_sectors

[GOTO Masanori <gotom@debian.or.jp>]

At Tue, 10 Dec 2002 13:23:48 +0000,
Christoph Hellwig wrote:
> On Mon, Dec 09, 2002 at 08:55:41AM -0600, James Bottomley wrote:
> > For some reason, the SCSI core is now warning about drivers which don't set 
> > max_sectors.
> > 
> > Just for the record, we have two parameters in the template:
> > 
> > sg_tablesize which determines the maximum number of scatter gather entries the 
> > host can have (corresponds to max_phys_segments in the block layer), and
> > 
> > max_sectors, which imposes a maximum overall transfer length (corresponds to 
> > max_sectors in the block queue).
> > 
> > The comments over max_sectors list it as optional (if unset, we set it to the 
> > scsi equivalent of machine infinity---well, actually 1024, or 512Mb for usual 
> > blocks).
> > 
> > The reason it's unset on so many drivers is that usually, they have no 
> > absolute transfer limit, so they're just bounded by the number of entries in 
> > the scatter-gather list.
> > 
> > I can't see a reason to force every driver suddenly to have an arbitrary 
> > max_sectors, so if no-one objects, I'll pull out the warning.
> 
> I added this intentionally.  The default is set in scsi_register_host
> which is an obsolete interface.  This warning reminds driver writers to set
> the value explicitly, with scsi_add_host & friends they won't get a default
> anymore.

Except for explicitly max_sectors defined drivers, the definition of
max_sectors on each drivers' Scsi_Host_Template does not need for a
long time.

So, IMHO, we set .max_sectors (for example) MAX_SECTORS_ALL like
.sg_tablesize = SG_ALL for unaware drivers' Scsi_Host_Template, then
removing such warning. 

-- gotom