[pups] Major/minor device numbers and device names for MSCP drives?
C. H. Dickman
chd_1 at nktelco.net
Tue Jun 20 07:53:37 AEST 2006
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...
> Bob Armstrong
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