improving device file creation - (MAKEDEV-2.5)

J.A. Neitzel jan.listbox at
Tue Jan 16 13:25:36 PST 2001

On Tuesday 16 January 2001 13:15, Fabio Fracassi wrote:
 +- Richard Gollub -
> > 	IDE drives: total of 63 partitions (up to 4 of type 'primary', or 3
> > primaries plus 1 extended; and up to 59 logical partitions per
> > extended partition);
> >
> > 	SCSI drives: total of 15 partitions (structured like IDE in view of
> > statement in devices.txt to the effect that "partitions are handled
> > in the same way as for IDE disks...", that I understand to mean up to
> > 4 primary partitions or 3 primaries and 1 extended, capable of
> > holding up to 11 logical partitions).
> >
> > 	Given that the PT structure (software-wise) is independent whether
> > the hardware is this or that, the Number of Partitions must depend on
> > space (at prima facie) or hardware-independent external conventions.
> >
> > 	Hope hot to have confused even more the issue... :-)

> Well, your reasoning makes sence, but given the fact that there is more
> than one partitioning style, (and PT-Standard) I don't belive it has to
> do with hardware restrictions. IIRC the problem is just that the
> "Namespace" of minor (and major) numbers is restricted.  (They had to
> arrage 100 scsi devices against about 20 ide, so ide gets more
> partitions per device.) IIRC I read somewhere (probably in the kernel
> docs) that the restrictions do not apply any more with devfs, but don't
> "nail" me on it.

After reading your responses I simply have to say, "Thanks for 
enlightening me!" :D How minor numbers related to major numbers is 
something that I never quite understood... But reading your explains does 
tell me a lot! I'm no math wizard, but it seems to make a lot more sense 
now. *_big_smiles_of_contentment_*

The good thing about devices.txt is an average joe (that's me) can read 
through it.
1) and even if you don't get all the little details (like where minor 
numbers come from)
2) you can still see a very plain and simple pattern for how the devices 
are allocated
3) and understanding the bigger picture of how these things fit together 
is as important IMHO as the little details that make it happen.
"Computers don't make mistakes, but they do execute your mistakes
	with extreme precision."

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