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BSD 2.11 - man page for hp (bsd section 4)

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XP(4)											    XP(4)

       xp - generic SMD moving-head disk

	    NXPC    xp_controllers # Number of controllers
	    NXPD    xp_drives	   # RM02/03/05, RP04/05/06,
				   # CDC 9766, Fuji 160, etc.
	    BADSECT NO		   # Bad sector handling (see BUGS)

	    #Name Unit# Addr   Vector Br Handler(s)	 # Comments
	    xp	  ?	176700 254    5  xpintr 	 # xp driver

       major device number(s):
	    raw: 19
	    block: 10
       minor device encoding:
	    bits 0007 specify partition of XP drive
	    bits 0370 specify XP drive

       The  xp driver is a generic SMD storage module disk driver.  It can be adapted to most SMD
       controllers although bootstrapping will not necessarily be directly possible.  The  drives
       are  numbered from 0 to n on controller 0, from n+1 to m on controller 1, etc.  The drives
       may have different geometries.

       The xp driver is unique amoungst 2BSD drivers in its numbering of drives.   Other  drivers
       (ra  for example) number drives 0 thru 7 on controller 1, 8 thru 15 on controller 2 and so
       on.  xp on the other hand can have drives 0 and 1 on controller 1, drives 2, 3, 4 and 5 on
       controller 2 and drives 6, 7 and 8 on controller 3.  This is different from boot's view of
       the world, so if you are booting from other than unit 0 you may have to experiment a bit.

       Files with minor device numbers 0 through 7 refer to various portions of  drive	0;  minor
       devices	8  through 15 refer to drive 1, etc.  The standard device names begin with ``xp''
       followed by the drive number and then a letter a-h for partitions 0-7  respectively.   The
       character ? stands here for a drive number in the range 0-7.

       The  block  files  access  the disk via the system's normal buffering mechanism and may be
       read and written without regard to physical disk records.  There is also a `raw' interface
       which  provides for direct transmission between the disk and the user's read or write buf-
       fer.  A single read or write call results in exactly one I/O operation and  therefore  raw
       I/O  is considerably more efficient when many words are transmitted.  The names of the raw
       files conventionally begin with an extra `r.'

       In raw I/O the buffer must begin on a word (even) boundary, and counts should be a  multi-
       ple  of	512 bytes (a disk sector).  Likewise lseek calls should specify a multiple of 512

       Disks must be labeled using either the standalone disklabel program on the  boot  tape  or
       with  the disklabel(8) program.	The kernel no longer attempts to determine the drive type
       and geometry, instead reading this information from the disklabel.  There are no partition
       tables coded into the xp driver, these must be placed on the drive with disklabel.

       Special	files  should  only  be created for the partitions that are actually used, as the
       overlap in these addresses could lead to confusion otherwise.  Traditionally the xp?a par-
       tition  is  normally used for the root file system, the xp?b partition as a swap area, and
       the xp?c partition for pack-pack copying (it maps the entire disk).

       /dev/xp[0-7][a-h]   block files
       /dev/rxp[0-7][a-h]  raw files
       /dev/MAKEDEV	   script to create special files
       /dev/MAKEDEV.local  script to localize special files

       hk(4), ra(4), ram(4), rk(4), rl(4), rp(4), rx(4), si(4), dtab(5), autoconfig(8), newfs(8)

       xp%d%c: hard error sn%d cs2=%b er1=%b.  An unrecoverable error occurred during transfer of
       the  specified sector of the specified disk partition.  The contents of the two error reg-
       isters are also printed in octal and symbolically with bits decoded.  The error was either
       unrecoverable, or a large number of retry attempts (including offset positioning and drive
       recalibration) could not recover the error.

       xp%d: write locked.  The write protect switch was set  on  the  drive  when  a  write  was
       attempted.  The write operation is not recoverable.

       xp%d%c:	soft  ecc  sn%d.  A recoverable ECC error occurred on the specified sector of the
       specified disk partition.  This happens normally a few times a week.  If it  happens  more
       frequently  than  this the sectors where the errors are occurring should be checked to see
       if certain cylinders on the pack, spots on the carriage of the drive or	heads  are  indi-

       xp%d:  unknown  device type 0%o.  The number in the drive's drive type register is unknown
       to the xp driver.

       In raw I/O read and write(2) truncate file offsets to 512-byte block boundaries, and write
       scribbles  on  the tail of incomplete blocks.  Thus, in programs that are likely to access
       raw devices, read, write and lseek(2) should always deal in 512-byte multiples.

       DEC-standard error logging should be supported.

       The kernel uses partition 'h' to access the badblock information.  This should  have  been
       'c' except that almost all of the /etc/disktab entries (and thus existing systems) use 'h'
       for this purpose.  Unless you are very careful with disklabel|(8) (to make certain that no
       data  partition overlaps the badblock area) you should probably leave BADSECT undefined in
       the kernel config file.

3rd Berkeley Distribution		 August 14, 1995				    XP(4)
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