Re: Larger dev_t

Andre Hedrick
2001-03-27T22:03:37Z

On Tue, 27 Mar 2001, Linus Torvalds wrote:

>
>
> On Tue, 27 Mar 2001, Alan Cox wrote:
> >
> > > layer made it impossible for a driver writer to be nice to the user, so
> > > instead they got their own major numbers.
> >
> > Not deficiencies in the SCSI layer, there is no way the scsi layer can
> > handle high end raid controllers. In fact one of the reasons we can beat
> > NT with some of these controllers is because NT does exactly what you
> > suggest with scsi miniport driver hacks and it _sucks_. Its an ugly hack.
>
> We could do this fairly _trivially_ today.
>
> With absolutely no performance degradation.
>
> With a simple "queue" mapping for the SCSI majors. Just look up which
> queue to use for requests to which major, and you're done. The actual
> IO may by-pass the SCSI layer altogether.
>
> So I'm absolutely not advocating using the SCSI layer for the
> high-end-disks. Rather the reverse. I'm advocating the SCSI layer not
> hogging a major number, but letting low-level drivers get at _their_
> requests directly.

Am I hearing you state you want dynamic device points and dynamic majors?
Thus would be nice because the ridge structure now prevents a lot if
things from developing.

Andre Hedrick
Linux ATA Development
ASL Kernel Development
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