Subject: Re: Port independent cdevsw[]
To: None <>
From: Greg A. Woods <>
List: tech-kern
Date: 10/15/2000 13:37:39
[ On Sunday, October 15, 2000 at 18:03:33 (+0200), Lennart Augustsson wrote: ]
> Subject: Port independent cdevsw[]
> Why do we have a cdevsw[] and bdevsw[] for each port?  Purely historical
> reasons I'd say.  It's a real nuisance.  Whenever you add a MI device
> driver you have to change far to many places.  You need to update the
> conf.c file for all ports that can have the device, and then the MAKEDEV
> for the corresponding ports.  This is annoying and error prone.

IIRC it's because ports try to keep major/minor compatible with the
original vendor-supplied OS for that platform....

> I suggest that we switch over to having a mostly port independent [bc]devsw
> tables.  There is still a need to have port specific drivers so I suggest the
> following design:
>     Set aside a part of the major device numbers for port specific driver,
>     say 0-255.  The table for this will be port specific.
>     The rest of the major numbers are port independent and stored in a
>     central table.

Much better would be if config(8) allocated the actual slot numbers from
a common table -- hand-hacking *devsw[] entries is really bogus!  That
common table could then driver MAKEDEV and all would be one!

							Greg A. Woods

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