> Is the relationship between the minor number and partition letter
> documented anywhere then?

/dev/MAKEDEV maybe?

> The only half-relevant information I came across was in the
> 386bsd-faq which porportedly has some relevance to NetBSD:-

>         These densities are established by a table from the file
>         /usr/src/sys/arch/i386/isa/fd.c (in NetBSD, your mileage may
>         vary).  The table in FreeBSD's fd.c is likely to be slightly
>         different.
> 
>         The order of the entries defines the order of the minor
>         numbers, so the table below has the following
>         characteristics:
> 
>             /dev/fd0a   1       /* 1.44MB diskette */ 
>             /dev/fd0b   2       /* 1.2 MB AT-diskettes */ 
>             /dev/fd0c   3       /* 360kB in 1.2MB drive */ 
>             /dev/fd0d   4       /* 360kB PC diskettes */ 
>             /dev/fd0e   5       /* 3.5" 720kB diskette */ 
>             /dev/fd0f   6       /* 720kB in 1.2MB drive */ 
>             /dev/fd0g   7       /* 360kB in 720kB drive */

This looks odd.  The second column certainly is not indices into the
table; the numbers are one too high for that.  They are quite likely
minor device numbers (they're the correct values), but then the
partition letters are off-by-one, assuming the usual mapping.  Perhaps
FreeBSD uses fd0h for the boot-time default, with a-g for specific
densities, versus NetBSD using fd0a for the default with b-h for
specific densities?

					der Mouse

			    mouse@collatz.mcrcim.mcgill.edu