1Magnetic Tape ioctl's are just (again) a compatibility problem with Linux.
2
3
4The /etc/rmt protocol allows to send ioctls to the remote system and relies on
5the fact that  MTIO opcodes 0..7 of all UNIX systems are mapped to the same function.
6Linux unfortunately does not follow these rules.
7
8/*--------------------------------------------------------------------------*/
9All other UNIX
10/*--------------------------------------------------------------------------*/
11/*
12 * values for mt_op
13 */
14#define	MTWEOF		0	/* write an end-of-file record */
15#define	MTFSF		1	/* forward space over file mark */
16#define	MTBSF		2	/* backward space over file mark (1/2" only ) */
17#define	MTFSR		3	/* forward space to inter-record gap */
18#define	MTBSR		4	/* backward space to inter-record gap */
19#define	MTREW		5	/* rewind */
20#define	MTOFFL		6	/* rewind and put the drive offline */
21#define	MTNOP		7	/* no operation, sets status only */
22
23/*--------------------------------------------------------------------------*/
24Linux
25/*--------------------------------------------------------------------------*/
26/* Magnetic Tape operations [Not all operations supported by all drivers]: */
27#define MTRESET	0	/* +reset drive in case of problems */
28#define MTFSF	1	/* forward space over FileMark,
29			 * position at first record of next file
30			 */
31#define MTBSF	2	/* backward space FileMark (position before FM) */
32#define MTFSR	3	/* forward space record */
33#define MTBSR	4	/* backward space record */
34#define MTWEOF	5	/* write an end-of-file record (mark) */
35#define MTREW	6	/* rewind */
36#define MTOFFL	7	/* rewind and put the drive offline (eject?) */
37#define MTNOP	8	/* no op, set status only (read with MTIOCGET) */
38
39Operation	Description			UNIX -> Linux
40====================================================================
410 weof		writes EOF (file mark)		resets drive!!!
421 fsf		forward skip file mark		OK
432 bsf		backwd skip file mark		OK
443 fsr		forward skip record		OK
454 bsr		backwd skip record		OK
465 rew		rewind				writes file mark!!!
476 offl		unload media			partially OK
487 nop		set status in driver		unloads media
498						NOP is mapped to the vendor dependant
50						range. On Sun this is a retension
51						which takes a long time...
52
53
54The rmt server and client code used in the star distribution voids
55these problems with Linux.
56
57