19 Jun
2006
19 Jun
'06
11:53 p.m.
Robert Armstrong wrote:
Probably this is documented somewhere, but I really
need a pointer
or a brief tutorial on the major/minor device numbers for mknod() and
the device names for MSCP drives in 2.11bsd.
If I have a really simple PDP with an RQDXn and one RDxx disk, then
the device name is conventionally /dev/ra0x and the first partition,
ra0a is (5,0), the second, ra0b, is (5,1), etc. Pretty easy.
If I have two drives on my single RQDXn, then the second hard disk
is /dev/ra1 and ra1a is (5,8), ra1b is (5,9), etc. I guess the offset
of 8 must be the maximum number of partitions on a drive - OK, I'm
still with you.
But what if I have a second MSCP controller? Assuming that I've
built the kernel to handle it and modified dtab to autoconfigure it,
that is. What are the usual names and mknod() numbers for the drives
on the second controller?
The second controller starts at ra8a (5, 8), and ra8a
must be MSCP unit 0.
Worse, what if the MSCP controller isn't a RQDX
but is a real
UDA/QDA ? Now the drives have their own MSCP unit numbers that can be
anything from 0 to 250 - where does this figure in?
An MSCP unit number greater
than 8 cannot be accessed from 2.11BSD.
Same question for TMSCP - what if I have more than
one tape
controller? This case is easier, though, since TMSCP controllers
normally have only one drive associated with them.
Don't know a think about
it...
Thanks,
Bob Armstrong
-chuck