Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!hp-pcd!hpfcso!chance
From: chance@hpfcso.FC.HP.COM (Chance Brohm)
Newsgroups: comp.sys.hp
Subject: Re: Using the DDS drive
Message-ID: <7370326@hpfcso.FC.HP.COM>
Date: 1 Mar 91 03:00:55 GMT
References: <1991Feb14.233141.10571@objy.com>
Organization: Hewlett-Packard, Fort Collins, CO, USA
Lines: 48

/ cochran@hpcupt1.cup.hp.com (Bob Cochran) /
> This may or may not be your problem but it is a common mistake to attempt
> to use the mt(1) utility (whose man page specifies that the device file
> must be Berkeley-style) with the /dev/rmt/* device files which are shipped
> (with AT&T-style specified).  If the minor number associated with
> the device file has been ORed with 0x100000, then Berkeley-style is specified

Note that this (specific minor-bit) is architecture-dependent. On PA-RISC
(9000/[68]xx) systems with HP-UX 7.0, this information is correct. A safer
approach on these systems for making device files is the mksf(1m) command
(/etc/mksf).  Using mksf (instead of mknod), you can specify "-d tape1 -u"
on the commandline to make a Berkeley-style tape device special-file. Read
the manpage (especially the TAPE1 section) for the whole truth. See also the
lssf(1m) manpage for the (useful!) ability to decipher the minor-bits of
existing device special-files.

On 300s, the situation is both easier and harder. The easier part is that
300s don't really have the concept of "LUN"s (Logical Unit Number) per se;
instead the minor bits of the device special-file indicate the select code
and bus address directly - you choose (without having to reconfigure/reboot)
how/if to assign LUNs. The harder part is that the mksf command does not
exist for MC68K (9000/[34]xx) systems (reason: no kernel-wired LUNs => no
/etc/devices file => no mksf); you need to obtain (& read) the HP-UX System
Admin Manual (for S300/400) to decipher the driver-specific minor bits.
My (sorry, ancient! but still valid) copy of the HP-UX SA manual (HP Part #
98597-90059 10/87) has this information on pages 178-181 (9-track magtape).
In case you don't have the manual handy (bad! bad! ;-), here's (some of)
the bits for the 9000/[34]xx HP-UX 7.x tape drivers (character-major 5 and 9):

 Minor number mask    SET (=1)  RESET (=0)
   0x000001           NoRewind  RewindOnClose
   0x000002           Berkeley  AT&T
   0x00FF00           Put the bus address here (MinorNum |= HPIBaddr << 8)
   0xFF0000           Put the select code here (MinorNum |= SelectCode << 16)

So for example, if you had an HPIB DDS drive set to 7978-compatibility mode
at HPIB address 0 and connected to the internal 300 HPIB (select code 7),
you could use the following commands to create Berkeley-style rewind and
no-rewind device special-files respectively:

/etc/mknod /dev/dds0  c 9 0x070002  # make a BSD rewind-on-close special-file
/etc/mknod /dev/dds0n c 9 0x070003  # make a BSD no-rewind special-file

Enjoy! -Chance

This message must not be considered to be an official statement of any kind;
the information is presented as-is with no warranty of correctness or fitness
for any purpose.