Re: [PATCH 2.4.x] prevent emulated SCSI hosts from wasting DMA memory

[Marcelo Tosatti <marcelo.tosatti@cyclades.com>]

On Thu, Dec 01, 2005 at 11:36:10AM +0000, Christoph Hellwig wrote:
> On Wed, Nov 30, 2005 at 11:02:23PM +0200, Dan Aloni wrote:
> > On Wed, Nov 30, 2005 at 07:33:47PM +0000, Luke-Jr wrote:
> > > On Wednesday 30 November 2005 17:15, Dan Aloni wrote:
> > > > Emulated scsi hosts don't do DMA, so don't unnecessarily increase
> > > > the SCSI DMA pool.
> > > 
> > > They don't? Recently I learned(?) that apparently using hdparm -d on the 
> > > old /dev/hdX device still worked/applied when using ide-scsi... or do 
> > > "emulated scsi hosts" refer to something else?
> > 
> > Actually by 'do DMA' I meant use the scsi_malloc() interface - which 
> > is mostly used by low level drivers. The IDE drivers allocate their
> > DMA memory outside the SCSI layer. iSCSI hosts for instance, don't 
> > need to cause unnecessary DMA allocations.
> 
> (1) there's no guranteee a driver setting ->emulated can't use scsi_malloc
> (2) 2.4.x is very late in the cycle so there's just no point in putting this
>     in (and in 2.6.x scsi_malloc is gone fortunately)

Agreed - this does not sound like a critical bug fix to me.