Re: [PATCH] remove ide-scsi

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Tue, 2008-12-09 at 15:07 -0500, Jeff Garzik wrote:
> Mark Lord wrote:
> > Jeff Garzik wrote:
> >> Yinghai Lu wrote:
> >>> On Sat, Dec 6, 2008 at 3:48 PM, Jeff Garzik <jeff@garzik.org> wrote:
> > ..
> >>> interesting, so will get /dev/ada instead of /dev/sda?
> >>
> >> That is an interesting question.  The easiest thing is to allocate a 
> >> new 32-bit block major.  But the more compatible (and more 
> >> controversial) solution is to allocate from the SCSI disk blkmajor space.
> > ..
> > 
> > Perhaps "sdx" and "scdx" should simply be redefined as "System disk"
> > and "System CD", and moved under block layer ownership from SCSI ?
> 
> Yes, precisely.  SCSI and libata (and others) would allocate disk/MMC 
> majors from the block layer.

Actually, The mmc major will still be sr (11).  The split out disk major
will only really be used for the current block devices served by sd.

> The biggest problem with this plan is that it introduces a mismatch in 
> ioctl capabilities, a behavior change from the current situation where 
> SCSI exports SCSI_IOCTL_SEND_COMMAND

That's deprecated and has been for several years.

>  in addition to the more universal 
> SG_IO.  Installers and existing clients may rely on this portion of the 
> Linux application ABI.

Hopefully not.  It warns noisily on use of deprecated ioctls.  The door
lock ones still aren't, so libata will have to grow it's own removable
media handling for them, but I think all the rest are (except the
bus/host probes which return largely made up numbers).

James