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Based on kernel version 4.1. Page generated on 2015-06-28 12:14 EST.

1	The Linux NCR53C8XX/SYM53C8XX drivers README file
2	
3	Written by Gerard Roudier <groudier@free.fr>
4	21 Rue Carnot
5	95170 DEUIL LA BARRE - FRANCE
6	
7	29 May 1999
8	===============================================================================
9	
10	1.  Introduction
11	2.  Supported chips and SCSI features
12	3.  Advantages of the enhanced 896 driver
13	      3.1 Optimized SCSI SCRIPTS
14	      3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
15	4.  Memory mapped I/O versus normal I/O
16	5.  Tagged command queueing
17	6.  Parity checking
18	7.  Profiling information
19	8.  Control commands
20	      8.1  Set minimum synchronous period
21	      8.2  Set wide size
22	      8.3  Set maximum number of concurrent tagged commands
23	      8.4  Set order type for tagged command
24	      8.5  Set debug mode
25	      8.6  Clear profile counters
26	      8.7  Set flag (no_disc)
27	      8.8  Set verbose level
28	      8.9  Reset all logical units of a target
29	      8.10 Abort all tasks of all logical units of a target
30	9.  Configuration parameters
31	10. Boot setup commands
32	      10.1 Syntax
33	      10.2 Available arguments
34	             10.2.1  Master parity checking
35	             10.2.2  Scsi parity checking
36	             10.2.3  Scsi disconnections
37	             10.2.4  Special features
38	             10.2.5  Ultra SCSI support
39	             10.2.6  Default number of tagged commands
40	             10.2.7  Default synchronous period factor
41	             10.2.8  Negotiate synchronous with all devices
42	             10.2.9  Verbosity level
43	             10.2.10 Debug mode
44	             10.2.11 Burst max
45	             10.2.12 LED support
46	             10.2.13 Max wide
47	             10.2.14 Differential mode
48	             10.2.15 IRQ mode
49	             10.2.16 Reverse probe
50	             10.2.17 Fix up PCI configuration space
51	             10.2.18 Serial NVRAM
52	             10.2.19 Check SCSI BUS 
53	             10.2.20 Exclude a host from being attached
54	             10.2.21 Suggest a default SCSI id for hosts
55	             10.2.22 Enable use of IMMEDIATE ARBITRATION
56	      10.3 Advised boot setup commands
57	      10.4 PCI configuration fix-up boot option
58	      10.5 Serial NVRAM support boot option
59	      10.6 SCSI BUS checking boot option
60	      10.7 IMMEDIATE ARBITRATION boot option
61	11. Some constants and flags of the ncr53c8xx.h header file
62	12. Installation
63	13. Architecture dependent features
64	14. Known problems
65	      14.1 Tagged commands with Iomega Jaz device
66	      14.2 Device names change when another controller is added
67	      14.3 Using only 8 bit devices with a WIDE SCSI controller.
68	      14.4 Possible data corruption during a Memory Write and Invalidate
69	      14.5 IRQ sharing problems
70	15. SCSI problem troubleshooting
71	      15.1 Problem tracking
72	      15.2 Understanding hardware error reports
73	16. Synchronous transfer negotiation tables
74	      16.1 Synchronous timings for 53C875 and 53C860 Ultra-SCSI controllers
75	      16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
76	17. Serial NVRAM support (by Richard Waltham)
77	      17.1 Features
78	      17.2 Symbios NVRAM layout
79	      17.3 Tekram  NVRAM layout
80	18. Support for Big Endian
81	      18.1 Big Endian CPU
82	      18.2 NCR chip in Big Endian mode of operations
83	
84	===============================================================================
85	
86	1. Introduction
87	
88	The initial Linux ncr53c8xx driver has been a port of the ncr driver from 
89	FreeBSD that has been achieved in November 1995 by:
90	          Gerard Roudier              <groudier@free.fr>
91	
92	The original driver has been written for 386bsd and FreeBSD by:
93	          Wolfgang Stanglmeier        <wolf@cologne.de>
94	          Stefan Esser                <se@mi.Uni-Koeln.de>
95	
96	It is now available as a bundle of 2 drivers:
97	
98	- ncr53c8xx generic driver that supports all the SYM53C8XX family including 
99	  the earliest 810 rev. 1, the latest 896 (2 channel LVD SCSI controller) and
100	  the new 895A (1 channel LVD SCSI controller).
101	- sym53c8xx enhanced driver (a.k.a. 896 drivers) that drops support of oldest 
102	  chips in order to gain advantage of new features, as LOAD/STORE instructions 
103	  available since the 810A and hardware phase mismatch available with the 
104	  896 and the 895A.
105	
106	You can find technical information about the NCR 8xx family in the
107	PCI-HOWTO written by Michael Will and in the SCSI-HOWTO written by
108	Drew Eckhardt.
109	
110	Information about new chips is available at LSILOGIC web server:
111	
112	          http://www.lsilogic.com/
113	
114	SCSI standard documentations are available at SYMBIOS ftp server:
115	
116	          ftp://ftp.symbios.com/
117	
118	Useful SCSI tools written by Eric Youngdale are available at tsx-11:
119	
120	          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsiinfo-X.Y.tar.gz
121	          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsidev-X.Y.tar.gz
122	
123	These tools are not ALPHA but quite clean and work quite well.
124	It is essential you have the 'scsiinfo' package.
125	
126	This short documentation describes the features of the generic and enhanced
127	drivers, configuration parameters and control commands available through 
128	the proc SCSI file system read / write operations.
129	
130	This driver has been tested OK with linux/i386, Linux/Alpha and Linux/PPC.
131	
132	Latest driver version and patches are available at:
133	
134	          ftp://ftp.tux.org/pub/people/gerard-roudier
135	or
136	          ftp://ftp.symbios.com/mirror/ftp.tux.org/pub/tux/roudier/drivers
137	
138	I am not a native speaker of English and there are probably lots of
139	mistakes in this README file. Any help will be welcome.
140	
141	
142	2. Supported chips and SCSI features
143	
144	The following features are supported for all chips:
145	
146		Synchronous negotiation
147		Disconnection
148		Tagged command queuing
149		SCSI parity checking
150		Master parity checking
151	
152	"Wide negotiation" is supported for chips that allow it.  The
153	following table shows some characteristics of NCR 8xx family chips 
154	and what drivers support them.
155	
156	                                                  Supported by   Supported by
157	       On board                                   the generic    the enhanced 
158	Chip   SDMS BIOS   Wide   SCSI std.   Max. sync   driver         driver
159	----   ---------   ----   ---------   ----------  ------------   -------------
160	810        N         N      FAST10    10 MB/s        Y             N
161	810A       N         N      FAST10    10 MB/s        Y             Y
162	815        Y         N      FAST10    10 MB/s        Y             N
163	825        Y         Y      FAST10    20 MB/s        Y             N
164	825A       Y         Y      FAST10    20 MB/s        Y             Y
165	860        N         N      FAST20    20 MB/s        Y             Y
166	875        Y         Y      FAST20    40 MB/s        Y             Y
167	876        Y         Y      FAST20    40 MB/s        Y             Y
168	895        Y         Y      FAST40    80 MB/s        Y             Y
169	895A       Y         Y      FAST40    80 MB/s        Y             Y
170	896        Y         Y      FAST40    80 MB/s        Y             Y
171	897        Y         Y      FAST40    80 MB/s        Y             Y
172	1510D      Y         Y      FAST40    80 MB/s        Y             Y
173	1010       Y         Y      FAST80   160 MB/s        N             Y
174	1010_66*   Y         Y      FAST80   160 MB/s        N             Y
175	
176	* Chip supports 33MHz and 66MHz PCI buses.
177	
178	
179	Summary of other supported features:
180	
181	Module:                allow to load the driver
182	Memory mapped I/O:     increases performance
183	Profiling information: read operations from the proc SCSI file system
184	Control commands:      write operations to the proc SCSI file system
185	Debugging information: written to syslog (expert only)
186	Scatter / gather
187	Shared interrupt
188	Boot setup commands
189	Serial NVRAM:          Symbios and Tekram formats
190	
191	
192	3. Advantages of the enhanced 896 driver
193	
194	3.1 Optimized SCSI SCRIPTS.
195	
196	The 810A, 825A, 875, 895, 896 and 895A support new SCSI SCRIPTS instructions 
197	named LOAD and STORE that allow to move up to 1 DWORD from/to an IO register 
198	to/from memory much faster that the MOVE MEMORY instruction that is supported 
199	by the 53c7xx and 53c8xx family.
200	The LOAD/STORE instructions support absolute and DSA relative addressing 
201	modes.  The SCSI SCRIPTS had been entirely rewritten using LOAD/STORE instead 
202	of MOVE MEMORY instructions.
203	
204	3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
205	
206	The 896 and the 895A allows handling of the phase mismatch context from 
207	SCRIPTS (avoids the phase mismatch interrupt that stops the SCSI processor 
208	until the C code has saved the context of the transfer).
209	Implementing this without using LOAD/STORE instructions would be painful 
210	and I didn't even want to try it.
211	
212	The 896 chip supports 64 bit PCI transactions and addressing, while the 
213	895A supports 32 bit PCI transactions and 64 bit addressing.
214	The SCRIPTS processor of these chips is not true 64 bit, but uses segment 
215	registers for bit 32-63. Another interesting feature is that LOAD/STORE 
216	instructions that address the on-chip RAM (8k) remain internal to the chip.
217	
218	Due to the use of LOAD/STORE SCRIPTS instructions, this driver does not 
219	support the following chips:
220	- SYM53C810 revision < 0x10 (16)
221	- SYM53C815 all revisions
222	- SYM53C825 revision < 0x10 (16)
223	
224	4. Memory mapped I/O versus normal I/O
225	
226	Memory mapped I/O has less latency than normal I/O.  Since
227	linux-1.3.x, memory mapped I/O is used rather than normal I/O.  Memory
228	mapped I/O seems to work fine on most hardware configurations, but
229	some poorly designed motherboards may break this feature.
230	
231	The configuration option CONFIG_SCSI_NCR53C8XX_IOMAPPED forces the
232	driver to use normal I/O in all cases.
233	
234	
235	5. Tagged command queueing
236	
237	Queuing more than 1 command at a time to a device allows it to perform 
238	optimizations based on actual head positions and its mechanical 
239	characteristics. This feature may also reduce average command latency.
240	In order to really gain advantage of this feature, devices must have 
241	a reasonable cache size (No miracle is to be expected for a low-end 
242	hard disk with 128 KB or less).
243	Some known SCSI devices do not properly support tagged command queuing.
244	Generally, firmware revisions that fix this kind of problems are available 
245	at respective vendor web/ftp sites.
246	All I can say is that the hard disks I use on my machines behave well with 
247	this driver with tagged command queuing enabled:
248	
249	- IBM S12 0662
250	- Conner 1080S
251	- Quantum Atlas I
252	- Quantum Atlas II
253	
254	If your controller has NVRAM, you can configure this feature per target 
255	from the user setup tool. The Tekram Setup program allows to tune the 
256	maximum number of queued commands up to 32. The Symbios Setup only allows 
257	to enable or disable this feature.
258	
259	The maximum number of simultaneous tagged commands queued to a device
260	is currently set to 8 by default.  This value is suitable for most SCSI
261	disks.  With large SCSI disks (>= 2GB, cache >= 512KB, average seek time
262	<= 10 ms), using a larger value may give better performances.
263	
264	The sym53c8xx driver supports up to 255 commands per device, and the 
265	generic ncr53c8xx driver supports up to 64, but using more than 32 is 
266	generally not worth-while, unless you are using a very large disk or disk 
267	array. It is noticeable that most of recent hard disks seem not to accept 
268	more than 64 simultaneous commands. So, using more than 64 queued commands 
269	is probably just resource wasting.
270	
271	If your controller does not have NVRAM or if it is managed by the SDMS 
272	BIOS/SETUP, you can configure tagged queueing feature and device queue 
273	depths from the boot command-line. For example:
274	
275	  ncr53c8xx=tags:4/t2t3q15-t4q7/t1u0q32
276	
277	will set tagged commands queue depths as follow:
278	
279	- target 2  all luns  on controller 0 --> 15
280	- target 3  all luns  on controller 0 --> 15
281	- target 4  all luns  on controller 0 -->  7
282	- target 1  lun 0     on controller 1 --> 32
283	- all other target/lun                -->  4
284	
285	In some special conditions, some SCSI disk firmwares may return a
286	QUEUE FULL status for a SCSI command. This behaviour is managed by the
287	driver using the following heuristic:
288	
289	- Each time a QUEUE FULL status is returned, tagged queue depth is reduced 
290	  to the actual number of disconnected commands. 
291	
292	- Every 1000 successfully completed SCSI commands, if allowed by the
293	  current limit, the maximum number of queueable commands is incremented.
294	
295	Since QUEUE FULL status reception and handling is resource wasting, the 
296	driver notifies by default this problem to user by indicating the actual 
297	number of commands used and their status, as well as its decision on the 
298	device queue depth change.
299	The heuristic used by the driver in handling QUEUE FULL ensures that the 
300	impact on performances is not too bad. You can get rid of the messages by 
301	setting verbose level to zero, as follow:
302	
303	1st method: boot your system using 'ncr53c8xx=verb:0' option.
304	2nd method: apply "setverbose 0" control command to the proc fs entry 
305	            corresponding to your controller after boot-up.
306	
307	6. Parity checking
308	
309	The driver supports SCSI parity checking and PCI bus master parity
310	checking.  These features must be enabled in order to ensure safe data
311	transfers.  However, some flawed devices or mother boards will have
312	problems with parity. You can disable either PCI parity or SCSI parity 
313	checking by entering appropriate options from the boot command line.
314	(See 10: Boot setup commands).
315	
316	7. Profiling information
317	
318	Profiling information is available through the proc SCSI file system.
319	Since gathering profiling information may impact performances, this 
320	feature is disabled by default and requires a compilation configuration 
321	option to be set to Y.
322	
323	The device associated with a host has the following pathname:
324	
325	          /proc/scsi/ncr53c8xx/N     (N=0,1,2 ....)
326	
327	Generally, only 1 board is used on hardware configuration, and that device is:
328	          /proc/scsi/ncr53c8xx/0
329	
330	However, if the driver has been made as module, the number of the
331	hosts is incremented each time the driver is loaded.
332	
333	In order to display profiling information, just enter:
334	
335	         cat /proc/scsi/ncr53c8xx/0
336	
337	and you will get something like the following text:
338	
339	-------------------------------------------------------
340	General information:
341	  Chip NCR53C810, device id 0x1, revision id 0x2
342	  IO port address 0x6000, IRQ number 10
343	  Using memory mapped IO at virtual address 0x282c000
344	  Synchronous transfer period 25, max commands per lun 4
345	Profiling information:
346	  num_trans    = 18014
347	  num_kbytes   = 671314
348	  num_disc     = 25763
349	  num_break    = 1673
350	  num_int      = 1685
351	  num_fly      = 18038
352	  ms_setup     = 4940
353	  ms_data      = 369940
354	  ms_disc      = 183090
355	  ms_post      = 1320
356	-------------------------------------------------------
357	
358	General information is easy to understand. The device ID and the
359	revision ID identify the SCSI chip as follows:
360	
361	Chip    Device id     Revision Id
362	----    ---------     -----------
363	810       0x1            <  0x10
364	810A      0x1            >= 0x10
365	815       0x4
366	825       0x3            <  0x10
367	860       0x6
368	825A      0x3            >= 0x10
369	875       0xf
370	895       0xc
371	
372	The profiling information is updated upon completion of SCSI commands.
373	A data structure is allocated and zeroed when the host adapter is
374	attached. So, if the driver is a module, the profile counters are
375	cleared each time the driver is loaded.  The "clearprof" command
376	allows you to clear these counters at any time.
377	
378	The following counters are available:
379	
380	("num" prefix means "number of",
381	"ms" means milli-seconds)
382	
383	num_trans
384		Number of completed commands
385		Example above: 18014 completed commands
386	
387	num_kbytes
388		Number of kbytes transferred
389		Example above: 671 MB transferred
390	
391	num_disc
392		Number of SCSI disconnections
393		Example above: 25763 SCSI disconnections
394	
395	num_break
396		number of script interruptions (phase mismatch)
397		Example above: 1673 script interruptions
398	
399	num_int
400		Number of interrupts other than "on the fly"
401		Example above: 1685 interruptions not "on the fly"
402	
403	num_fly
404		Number of interrupts "on the fly"
405		Example above: 18038 interruptions "on the fly"
406	
407	ms_setup
408		Elapsed time for SCSI commands setups
409		Example above: 4.94 seconds
410	
411	ms_data
412		Elapsed time for data transfers
413		Example above: 369.94 seconds spent for data transfer
414	
415	ms_disc
416		Elapsed time for SCSI disconnections
417		Example above: 183.09 seconds spent disconnected
418	
419	ms_post
420		Elapsed time for command post processing
421		(time from SCSI status get to command completion call)
422		Example above: 1.32 seconds spent for post processing
423	
424	Due to the 1/100 second tick of the system clock, "ms_post" time may
425	be wrong.
426	
427	In the example above, we got 18038 interrupts "on the fly" and only
428	1673 script breaks generally due to disconnections inside a segment 
429	of the scatter list.
430	
431	
432	8. Control commands
433	
434	Control commands can be sent to the driver with write operations to
435	the proc SCSI file system. The generic command syntax is the
436	following:
437	
438	      echo "<verb> <parameters>" >/proc/scsi/ncr53c8xx/0
439	      (assumes controller number is 0)
440	
441	Using "all" for "<target>" parameter with the commands below will
442	apply to all targets of the SCSI chain (except the controller).
443	
444	Available commands:
445	
446	8.1 Set minimum synchronous period factor
447	
448	    setsync <target> <period factor>
449	
450	    target:    target number
451	    period:    minimum synchronous period.
452	               Maximum speed = 1000/(4*period factor) except for special
453	               cases below.
454	
455	    Specify a period of 255, to force asynchronous transfer mode.
456	
457	      10 means 25 nano-seconds synchronous period
458	      11 means 30 nano-seconds synchronous period
459	      12 means 50 nano-seconds synchronous period
460	
461	8.2 Set wide size
462	
463	    setwide <target> <size>
464	
465	    target:    target number
466	    size:      0=8 bits, 1=16bits
467	
468	8.3 Set maximum number of concurrent tagged commands
469	 
470	    settags <target> <tags>
471	
472	    target:    target number
473	    tags:      number of concurrent tagged commands
474	               must not be greater than SCSI_NCR_MAX_TAGS (default: 8)
475	
476	8.4 Set order type for tagged command
477	
478	    setorder <order>
479	
480	    order:     3 possible values:
481	               simple: use SIMPLE TAG for all operations (read and write)
482	               ordered: use ORDERED TAG for all operations
483	               default: use default tag type,
484	                        SIMPLE  TAG for read  operations
485	                        ORDERED TAG for write operations
486	
487	
488	8.5 Set debug mode
489	
490	    setdebug <list of debug flags>
491	
492	    Available debug flags:
493	        alloc:   print info about memory allocations (ccb, lcb)
494	        queue:   print info about insertions into the command start queue
495	        result:  print sense data on CHECK CONDITION status
496	        scatter: print info about the scatter process
497	        scripts: print info about the script binding process
498		tiny:    print minimal debugging information
499		timing:  print timing information of the NCR chip
500		nego:    print information about SCSI negotiations
501		phase:   print information on script interruptions
502	
503	    Use "setdebug" with no argument to reset debug flags.
504	
505	
506	8.6 Clear profile counters
507	
508	    clearprof
509	
510	    The profile counters are automatically cleared when the amount of
511	    data transferred reaches 1000 GB in order to avoid overflow.
512	    The "clearprof" command allows you to clear these counters at any time.
513	
514	
515	8.7 Set flag (no_disc)
516	 
517	    setflag <target> <flag>
518	
519	    target:    target number
520	
521	    For the moment, only one flag is available:
522	
523	        no_disc:   not allow target to disconnect.
524	
525	    Do not specify any flag in order to reset the flag. For example:
526	    - setflag 4
527	      will reset no_disc flag for target 4, so will allow it disconnections.
528	    - setflag all
529	      will allow disconnection for all devices on the SCSI bus.
530	
531	
532	8.8 Set verbose level
533	
534	    setverbose #level
535	
536	    The driver default verbose level is 1. This command allows to change 
537	    th driver verbose level after boot-up.
538	
539	8.9 Reset all logical units of a target
540	
541	    resetdev <target>
542	
543	    target:    target number
544	    The driver will try to send a BUS DEVICE RESET message to the target.
545	    (Only supported by the SYM53C8XX driver and provided for test purpose)
546	
547	8.10 Abort all tasks of all logical units of a target
548	
549	    cleardev <target>
550	
551	    target:    target number
552	    The driver will try to send a ABORT message to all the logical units 
553	    of the target.
554	    (Only supported by the SYM53C8XX driver and provided for test purpose)
555	
556	
557	9. Configuration parameters
558	
559	If the firmware of all your devices is perfect enough, all the
560	features supported by the driver can be enabled at start-up.  However,
561	if only one has a flaw for some SCSI feature, you can disable the
562	support by the driver of this feature at linux start-up and enable
563	this feature after boot-up only for devices that support it safely.
564	
565	CONFIG_SCSI_NCR53C8XX_IOMAPPED       (default answer: n)
566	    Answer "y" if you suspect your mother board to not allow memory mapped I/O.
567	    May slow down performance a little.  This option is required by
568	    Linux/PPC and is used no matter what you select here.  Linux/PPC
569	    suffers no performance loss with this option since all IO is memory
570	    mapped anyway.
571	
572	CONFIG_SCSI_NCR53C8XX_DEFAULT_TAGS    (default answer: 8)
573	    Default tagged command queue depth.
574	
575	CONFIG_SCSI_NCR53C8XX_MAX_TAGS         (default answer: 8)
576	    This option allows you to specify the maximum number of tagged commands 
577	    that can be queued to a device. The maximum supported value is 32.
578	
579	CONFIG_SCSI_NCR53C8XX_SYNC            (default answer: 5)
580	    This option allows you to specify the frequency in MHz the driver 
581	    will use at boot time for synchronous data transfer negotiations.
582	    This frequency can be changed later with the "setsync" control command.
583	    0 means "asynchronous data transfers".
584	
585	CONFIG_SCSI_NCR53C8XX_FORCE_SYNC_NEGO (default answer: n)
586	    Force synchronous negotiation for all SCSI-2 devices.
587	    Some SCSI-2 devices do not report this feature in byte 7 of inquiry 
588	    response but do support it properly (TAMARACK scanners for example).
589	
590	CONFIG_SCSI_NCR53C8XX_NO_DISCONNECT   (default and only reasonable answer: n)
591	    If you suspect a device of yours does not properly support disconnections,
592	    you can answer "y". Then, all SCSI devices will never disconnect the bus 
593	    even while performing long SCSI operations.
594	
595	CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT
596	    Genuine SYMBIOS boards use GPIO0 in output for controller LED and GPIO3 
597	    bit as a flag indicating singled-ended/differential interface.
598	    If all the boards of your system are genuine SYMBIOS boards or use
599	    BIOS and drivers from SYMBIOS, you would want to enable this option.
600	    This option must NOT be enabled if your system has at least one 53C8XX 
601	    based scsi board with a vendor-specific BIOS.
602	    For example, Tekram DC-390/U, DC-390/W and DC-390/F scsi controllers 
603	    use a vendor-specific BIOS and are known to not use SYMBIOS compatible 
604	    GPIO wiring. So, this option must not be enabled if your system has 
605	    such a board installed.
606	
607	CONFIG_SCSI_NCR53C8XX_NVRAM_DETECT
608	    Enable support for reading the serial NVRAM data on Symbios and
609	    some Symbios compatible cards, and Tekram DC390W/U/F cards. Useful for
610	    systems with more than one Symbios compatible controller where at least
611	    one has a serial NVRAM, or for a system with a mixture of Symbios and
612	    Tekram cards. Enables setting the boot order of host adaptors
613	    to something other than the default order or "reverse probe" order. 
614	    Also enables Symbios and Tekram cards to be distinguished so
615	    CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT may be set in a system with a
616	    mixture of Symbios and Tekram cards so the Symbios cards can make use of
617	    the full range of Symbios features, differential, led pin, without
618	    causing problems for the Tekram card(s).
619	
620	10. Boot setup commands
621	
622	10.1 Syntax
623	
624	Setup commands can be passed to the driver either at boot time or as a 
625	string variable using 'insmod'.
626	
627	A boot setup command for the ncr53c8xx (sym53c8xx) driver begins with the 
628	driver name "ncr53c8xx="(sym53c8xx). The kernel syntax parser then expects 
629	an optional list of integers separated with comma followed by an optional 
630	list of comma-separated strings. Example of boot setup command under lilo 
631	prompt:
632	
633	lilo: linux root=/dev/hda2 ncr53c8xx=tags:4,sync:10,debug:0x200
634	
635	- enable tagged commands, up to 4 tagged commands queued.
636	- set synchronous negotiation speed to 10 Mega-transfers / second.
637	- set DEBUG_NEGO flag.
638	
639	Since comma seems not to be allowed when defining a string variable using  
640	'insmod', the driver also accepts <space> as option separator. 
641	The following command will install driver module with the same options as 
642	above.
643	
644	    insmod ncr53c8xx.o ncr53c8xx="tags:4 sync:10 debug:0x200"
645	
646	For the moment, the integer list of arguments is discarded by the driver. 
647	It will be used in the future in order to allow a per controller setup.
648	
649	Each string argument must be specified as "keyword:value". Only lower-case 
650	characters and digits are allowed.
651	
652	In a system that contains multiple 53C8xx adapters insmod will install the 
653	specified driver on each adapter. To exclude a chip use the 'excl' keyword.
654	
655	The sequence of commands, 
656	
657	    insmod sym53c8xx sym53c8xx=excl:0x1400
658	    insmod ncr53c8xx
659	
660	installs the sym53c8xx driver on all adapters except the one at IO port 
661	address 0x1400 and then installs the ncr53c8xx driver to the adapter at IO 
662	port address 0x1400.
663	
664	
665	10.2 Available arguments
666	
667	10.2.1  Master parity checking
668	        mpar:y     enabled
669	        mpar:n     disabled
670	
671	10.2.2  Scsi parity checking
672	        spar:y     enabled
673	        spar:n     disabled
674	
675	10.2.3  Scsi disconnections
676	        disc:y     enabled
677	        disc:n     disabled
678	 
679	10.2.4  Special features
680	   Only apply to 810A, 825A, 860, 875 and 895 controllers.
681	   Have no effect with other ones.
682	        specf:y    (or 1) enabled
683	        specf:n    (or 0) disabled
684	        specf:3           enabled except Memory Write And Invalidate
685	   The default driver setup is 'specf:3'. As a consequence, option 'specf:y' 
686	   must be specified in the boot setup command to enable Memory Write And 
687	   Invalidate.
688	
689	10.2.5  Ultra SCSI support
690	   Only apply to 860, 875, 895, 895a, 896, 1010 and 1010_66 controllers.
691	   Have no effect with other ones.
692	        ultra:n    All ultra speeds enabled
693	        ultra:2    Ultra2 enabled
694	        ultra:1    Ultra enabled
695	        ultra:0    Ultra speeds disabled
696	
697	10.2.6  Default number of tagged commands
698	        tags:0     (or tags:1 ) tagged command queuing disabled
699	        tags:#tags (#tags  > 1) tagged command queuing enabled
700	  #tags will be truncated to the max queued commands configuration parameter.
701	  This option also allows to specify a command queue depth for each device 
702	  that support tagged command queueing.
703	  Example:
704	      ncr53c8xx=tags:10/t2t3q16-t5q24/t1u2q32
705	               will set devices queue depth as follow:
706	      - controller #0 target #2 and target #3                  -> 16 commands,
707	      - controller #0 target #5                                -> 24 commands,
708	      - controller #1 target #1 logical unit #2                -> 32 commands,
709	      - all other logical units (all targets, all controllers) -> 10 commands.
710	
711	10.2.7  Default synchronous period factor
712	        sync:255     disabled (asynchronous transfer mode)
713	        sync:#factor
714	  #factor = 10     Ultra-2 SCSI 40 Mega-transfers / second
715	  #factor = 11     Ultra-2 SCSI 33 Mega-transfers / second
716	  #factor < 25     Ultra   SCSI 20 Mega-transfers / second
717	  #factor < 50     Fast    SCSI-2
718	
719	  In all cases, the driver will use the minimum transfer period supported by 
720	  controllers according to NCR53C8XX chip type.
721	
722	10.2.8  Negotiate synchronous with all devices
723	        (force sync nego)
724	        fsn:y      enabled
725	        fsn:n      disabled
726	
727	10.2.9  Verbosity level
728	        verb:0     minimal
729	        verb:1     normal
730	        verb:2     too much
731	
732	10.2.10 Debug mode
733	        debug:0	 clear debug flags
734	        debug:#x   set debug flags
735	  #x is an integer value combining the following power-of-2 values:
736	  DEBUG_ALLOC       0x1
737	  DEBUG_PHASE       0x2
738	  DEBUG_POLL        0x4
739	  DEBUG_QUEUE       0x8
740	  DEBUG_RESULT     0x10
741	  DEBUG_SCATTER    0x20
742	  DEBUG_SCRIPT     0x40
743	  DEBUG_TINY       0x80
744	  DEBUG_TIMING    0x100
745	  DEBUG_NEGO      0x200
746	  DEBUG_TAGS      0x400
747	  DEBUG_FREEZE    0x800
748	  DEBUG_RESTART  0x1000
749	
750	  You can play safely with DEBUG_NEGO. However, some of these flags may 
751	  generate bunches of syslog messages. 
752	
753	10.2.11 Burst max
754	        burst:0    burst disabled
755	        burst:255  get burst length from initial IO register settings.
756	        burst:#x   burst enabled (1<<#x burst transfers max)
757	  #x is an integer value which is log base 2 of the burst transfers max.
758	  The NCR53C875 and NCR53C825A support up to 128 burst transfers (#x = 7).
759	  Other chips only support up to 16 (#x = 4).
760	  This is a maximum value. The driver set the burst length according to chip 
761	  and revision ids. By default the driver uses the maximum value supported 
762	  by the chip.
763	
764	10.2.12 LED support
765	        led:1      enable  LED support
766	        led:0      disable LED support
767	  Donnot enable LED support if your scsi board does not use SDMS BIOS.
768	  (See 'Configuration parameters')
769	
770	10.2.13 Max wide
771	        wide:1      wide scsi enabled
772	        wide:0      wide scsi disabled
773	  Some scsi boards use a 875 (ultra wide) and only supply narrow connectors.
774	  If you have connected a wide device with a 50 pins to 68 pins cable 
775	  converter, any accepted wide negotiation will break further data transfers.
776	  In such a case, using "wide:0" in the bootup command will be helpful. 
777	
778	10.2.14 Differential mode
779	        diff:0	never set up diff mode
780	        diff:1	set up diff mode if BIOS set it
781	        diff:2	always set up diff mode
782	        diff:3	set diff mode if GPIO3 is not set
783	
784	10.2.15 IRQ mode
785	        irqm:0     always open drain
786	        irqm:1     same as initial settings (assumed BIOS settings)
787	        irqm:2     always totem pole
788	        irqm:0x10  driver will not use IRQF_SHARED flag when requesting irq
789	
790	    (Bits 0x10 and 0x20 can be combined with hardware irq mode option)
791	
792	10.2.16 Reverse probe
793	        revprob:n   probe chip ids from the PCI configuration in this order:
794	                    810, 815, 820, 860, 875, 885, 895, 896
795	        revprob:y   probe chip ids in the reverse order.
796	
797	10.2.17 Fix up PCI configuration space
798	        pcifix:<option bits>
799	
800	    Available option bits:
801	        0x0:   No attempt to fix PCI configuration space registers values.
802	        0x1:   Set PCI cache-line size register if not set.
803	        0x2:   Set write and invalidate bit in PCI command register.
804	        0x4:   Increase if necessary PCI latency timer according to burst max.
805	
806	    Use 'pcifix:7' in order to allow the driver to fix up all PCI features.
807	
808	10.2.18 Serial NVRAM
809	        nvram:n     do not look for serial NVRAM
810	        nvram:y     test controllers for onboard serial NVRAM
811	        (alternate binary form)
812	        mvram=<bits options>
813	        0x01   look for NVRAM  (equivalent to nvram=y)
814	        0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
815	        0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
816	        0x08   ignore NVRAM "Scan at boot time" parameter for all devices
817	        0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
818	
819	10.2.19 Check SCSI BUS 
820	        buschk:<option bits>
821	
822	    Available option bits:
823	        0x0:   No check.
824	        0x1:   Check and do not attach the controller on error.  
825	        0x2:   Check and just warn on error.
826	        0x4:   Disable SCSI bus integrity checking.
827	
828	10.2.20 Exclude a host from being attached
829	        excl=<io_address>
830	
831	    Prevent host at a given io address from being attached.
832	    For example 'ncr53c8xx=excl:0xb400,excl:0xc000' indicate to the 
833	    ncr53c8xx driver not to attach hosts at address 0xb400 and 0xc000.
834	
835	10.2.21 Suggest a default SCSI id for hosts
836	        hostid:255	no id suggested.
837	        hostid:#x   (0 < x < 7) x suggested for hosts SCSI id.
838	
839	    If a host SCSI id is available from the NVRAM, the driver will ignore 
840	    any value suggested as boot option. Otherwise, if a suggested value 
841	    different from 255 has been supplied, it will use it. Otherwise, it will 
842	    try to deduce the value previously set in the hardware and use value 
843	    7 if the hardware value is zero.
844	
845	10.2.22 Enable use of IMMEDIATE ARBITRATION
846	        (only supported by the sym53c8xx driver. See 10.7 for more details)
847	        iarb:0    do not use this feature.
848	        iarb:#x   use this feature according to bit fields as follow:
849	
850	    bit 0 (1) : enable IARB each time the initiator has been reselected 
851	                when it arbitrated for the SCSI BUS.
852	    (#x >> 4) : maximum number of successive settings of IARB if the initiator 
853	                win arbitration and it has other commands to send to a device.
854	
855	Boot fail safe
856	    safe:y	load the following assumed fail safe initial setup
857	
858	  master parity			disabled		mpar:n
859	  scsi parity			enabled			spar:y
860	  disconnections		not allowed		disc:n
861	  special features		disabled		specf:n
862	  ultra scsi			disabled		ultra:n
863	  force sync negotiation	disabled		fsn:n
864	  reverse probe			disabled		revprob:n
865	  PCI fix up                    disabled                pcifix:0
866	  serial NVRAM                  enabled                 nvram:y
867	  verbosity level		2			verb:2
868	  tagged command queuing	disabled		tags:0
869	  synchronous negotiation	disabled		sync:255
870	  debug flags			none			debug:0
871	  burst length			from BIOS settings	burst:255
872	  LED support			disabled		led:0
873	  wide support			disabled		wide:0
874	  settle time			10 seconds		settle:10
875	  differential support		from BIOS settings	diff:1
876	  irq mode			from BIOS settings	irqm:1
877	  SCSI BUS check		do not attach on error	buschk:1
878	  immediate arbitration		disabled		iarb:0
879	
880	10.3 Advised boot setup commands
881	
882	If the driver has been configured with default options, the equivalent 
883	boot setup is:
884	
885	   ncr53c8xx=mpar:y,spar:y,disc:y,specf:3,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
886	             tags:0,sync:50,debug:0,burst:7,led:0,wide:1,settle:2,diff:0,irqm:0
887	
888	For an installation diskette or a safe but not fast system,
889	boot setup can be:
890	
891	    ncr53c8xx=safe:y,mpar:y,disc:y
892	    ncr53c8xx=safe:y,disc:y
893	    ncr53c8xx=safe:y,mpar:y
894	    ncr53c8xx=safe:y
895	
896	My personal system works flawlessly with the following equivalent setup:
897	
898	   ncr53c8xx=mpar:y,spar:y,disc:y,specf:1,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
899	             tags:32,sync:12,debug:0,burst:7,led:1,wide:1,settle:2,diff:0,irqm:0
900	
901	The driver prints its actual setup when verbosity level is 2. You can try 
902	"ncr53c8xx=verb:2" to get the "static" setup of the driver, or add "verb:2" 
903	to your boot setup command in order to check the actual setup the driver is 
904	using.
905	
906	10.4 PCI configuration fix-up boot option
907	
908	pcifix:<option bits>
909	
910	Available option bits:
911	    0x1:     Set PCI cache-line size register if not set.
912	    0x2:     Set write and invalidate bit in PCI command register.
913	
914	Use 'pcifix:3' in order to allow the driver to fix both PCI features.
915	
916	These options only apply to new SYMBIOS chips 810A, 825A, 860, 875 
917	and 895 and are only supported for Pentium and 486 class processors.
918	Recent SYMBIOS 53C8XX scsi processors are able to use PCI read multiple 
919	and PCI write and invalidate commands. These features require the 
920	cache line size register to be properly set in the PCI configuration 
921	space of the chips. On the other hand, chips will use PCI write and 
922	invalidate commands only if the corresponding bit is set to 1 in the 
923	PCI command register.
924	
925	Not all PCI bioses set the PCI cache line register and the PCI write and 
926	invalidate bit in the PCI configuration space of 53C8XX chips.
927	Optimized PCI accesses may be broken for some PCI/memory controllers or 
928	make problems with some PCI boards.
929	
930	This fix-up worked flawlessly on my previous system.
931	(MB Triton HX / 53C875 / 53C810A)
932	I use these options at my own risks as you will do if you decide to 
933	use them too.
934	
935	
936	10.5 Serial NVRAM support boot option
937	
938	nvram:n     do not look for serial NVRAM
939	nvram:y     test controllers for onboard serial NVRAM
940	
941	This option can also been entered as an hexadecimal value that allows 
942	to control what information the driver will get from the NVRAM and what 
943	information it will ignore.
944	For details see '17. Serial NVRAM support'.
945	
946	When this option is enabled, the driver tries to detect all boards using 
947	a Serial NVRAM. This memory is used to hold user set up parameters.
948	
949	The parameters the driver is able to get from the NVRAM depend on the 
950	data format used, as follow:
951	
952	                                 Tekram format      Symbios format
953	General and host parameters
954	    Boot order                         N                   Y
955	    Host SCSI ID                       Y                   Y
956	    SCSI parity checking               Y                   Y
957	    Verbose boot messages              N                   Y
958	SCSI devices parameters
959	    Synchronous transfer speed         Y                   Y
960	    Wide 16 / Narrow                   Y                   Y
961	    Tagged Command Queuing enabled     Y                   Y
962	    Disconnections enabled             Y                   Y
963	    Scan at boot time                  N                   Y
964	
965	In order to speed up the system boot, for each device configured without 
966	the "scan at boot time" option, the driver forces an error on the 
967	first TEST UNIT READY command received for this device.
968	
969	Some SDMS BIOS revisions seem to be unable to boot cleanly with very fast 
970	hard disks. In such a situation you cannot configure the NVRAM with 
971	optimized parameters value.
972	
973	The 'nvram' boot option can be entered in hexadecimal form in order 
974	to ignore some options configured in the NVRAM, as follow:
975	
976	mvram=<bits options>
977	      0x01   look for NVRAM  (equivalent to nvram=y)
978	      0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
979	      0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
980	      0x08   ignore NVRAM "Scan at boot time" parameter for all devices
981	      0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
982	
983	Option 0x80 is only supported by the sym53c8xx driver and is disabled by 
984	default. Result is that, by default (option not set), the sym53c8xx driver 
985	will not attach controllers set to OFF in the NVRAM.
986	
987	The ncr53c8xx always tries to attach all the controllers. Option 0x80 has 
988	not been added to the ncr53c8xx driver, since it has been reported to 
989	confuse users who use this driver since a long time. If you desire a 
990	controller not to be attached by the ncr53c8xx driver at Linux boot, you 
991	must use the 'excl' driver boot option.
992	
993	10.6 SCSI BUS checking boot option.
994	
995	When this option is set to a non-zero value, the driver checks SCSI lines 
996	logic state, 100 micro-seconds after having asserted the SCSI RESET line.
997	The driver just reads SCSI lines and checks all lines read FALSE except RESET.
998	Since SCSI devices shall release the BUS at most 800 nano-seconds after SCSI 
999	RESET has been asserted, any signal to TRUE may indicate a SCSI BUS problem.
1000	Unfortunately, the following common SCSI BUS problems are not detected:
1001	- Only 1 terminator installed.
1002	- Misplaced terminators.
1003	- Bad quality terminators.
1004	On the other hand, either bad cabling, broken devices, not conformant 
1005	devices, ... may cause a SCSI signal to be wrong when te driver reads it.
1006	
1007	10.7 IMMEDIATE ARBITRATION boot option
1008	
1009	This option is only supported by the SYM53C8XX driver (not by the NCR53C8XX).
1010	
1011	SYMBIOS 53C8XX chips are able to arbitrate for the SCSI BUS as soon as they 
1012	have detected an expected disconnection (BUS FREE PHASE). For this process 
1013	to be started, bit 1 of SCNTL1 IO register must be set when the chip is 
1014	connected to the SCSI BUS.
1015	
1016	When this feature has been enabled for the current connection, the chip has 
1017	every chance to win arbitration if only devices with lower priority are 
1018	competing for the SCSI BUS. By the way, when the chip is using SCSI id 7, 
1019	then it will for sure win the next SCSI BUS arbitration.
1020	
1021	Since, there is no way to know what devices are trying to arbitrate for the 
1022	BUS, using this feature can be extremely unfair. So, you are not advised
1023	to enable it, or at most enable this feature for the case the chip lost 
1024	the previous arbitration (boot option 'iarb:1').
1025	
1026	This feature has the following advantages:
1027	
1028	a) Allow the initiator with ID 7 to win arbitration when it wants so.
1029	b) Overlap at least 4 micro-seconds of arbitration time with the execution 
1030	   of SCRIPTS that deal with the end of the current connection and that 
1031	   starts the next job.
1032	
1033	Hmmm... But (a) may just prevent other devices from reselecting the initiator, 
1034	and delay data transfers or status/completions, and (b) may just waste 
1035	SCSI BUS bandwidth if the SCRIPTS execution lasts more than 4 micro-seconds.
1036	
1037	The use of IARB needs the SCSI_NCR_IARB_SUPPORT option to have been defined 
1038	at compile time and the 'iarb' boot option to have been set to a non zero 
1039	value at boot time. It is not that useful for real work, but can be used 
1040	to stress SCSI devices or for some applications that can gain advantage of 
1041	it. By the way, if you experience badnesses like 'unexpected disconnections', 
1042	'bad reselections', etc... when using IARB on heavy IO load, you should not 
1043	be surprised, because force-feeding anything and blocking its arse at the 
1044	same time cannot work for a long time. :-))
1045	
1046	
1047	11. Some constants and flags of the ncr53c8xx.h header file
1048	
1049	Some of these are defined from the configuration parameters.  To
1050	change other "defines", you must edit the header file.  Do that only
1051	if you know what you are doing.
1052	
1053	SCSI_NCR_SETUP_SPECIAL_FEATURES	(default: defined)
1054		If defined, the driver will enable some special features according  
1055		to chip and revision id.
1056	        For 810A, 860, 825A, 875 and 895 scsi chips, this option enables 
1057		support of features that reduce load of PCI bus and memory accesses 
1058		during  scsi transfer processing: burst op-code fetch, read multiple, 
1059	        read line, prefetch, cache line, write and invalidate, 
1060	        burst 128 (875 only), large dma fifo (875 only), offset 16 (875 only).
1061		Can be changed by the following boot setup command:
1062			ncr53c8xx=specf:n
1063	
1064	SCSI_NCR_IOMAPPED		(default: not defined)
1065		If defined, normal I/O is forced.
1066	
1067	SCSI_NCR_SHARE_IRQ		(default: defined)
1068		If defined, request shared IRQ.
1069		
1070	SCSI_NCR_MAX_TAGS		(default: 8)
1071		Maximum number of simultaneous tagged commands to a device.
1072		Can be changed by "settags <target> <maxtags>"
1073	
1074	SCSI_NCR_SETUP_DEFAULT_SYNC     (default: 50)
1075		Transfer period factor the driver will use at boot time for synchronous 
1076		negotiation. 0 means asynchronous.
1077		Can be changed by "setsync <target> <period factor>"
1078	
1079	SCSI_NCR_SETUP_DEFAULT_TAGS     (default: 8)
1080		Default number of simultaneous tagged commands to a device.
1081		< 1 means tagged command queuing disabled at start-up.
1082	
1083	SCSI_NCR_ALWAYS_SIMPLE_TAG	(default: defined)
1084		Use SIMPLE TAG for read and write commands.
1085		Can be changed by "setorder <ordered|simple|default>"
1086	
1087	SCSI_NCR_SETUP_DISCONNECTION	(default: defined)
1088		If defined, targets are allowed to disconnect.
1089	
1090	SCSI_NCR_SETUP_FORCE_SYNC_NEGO	(default: not defined)
1091		If defined, synchronous negotiation is tried for all SCSI-2 devices.
1092		Can be changed by "setsync <target> <period>"
1093	
1094	SCSI_NCR_SETUP_MASTER_PARITY	(default: defined)
1095		If defined, master parity checking is enabled.
1096	
1097	SCSI_NCR_SETUP_SCSI_PARITY	(default: defined)
1098		If defined, SCSI parity checking is enabled.
1099	
1100	SCSI_NCR_PROFILE_SUPPORT	(default: not defined)
1101		If defined, profiling information is gathered.
1102	
1103	SCSI_NCR_MAX_SCATTER		(default: 128)
1104		Scatter list size of the driver ccb.
1105	
1106	SCSI_NCR_MAX_TARGET		(default: 16)
1107		Max number of targets per host.
1108	
1109	SCSI_NCR_MAX_HOST		(default: 2)
1110		Max number of host controllers.
1111	
1112	SCSI_NCR_SETTLE_TIME		(default: 2)
1113		Number of seconds the driver will wait after reset.
1114	
1115	SCSI_NCR_TIMEOUT_ALERT		(default: 3)
1116		If a pending command will time out after this amount of seconds,
1117		an ordered tag is used for the next command.
1118		Avoids timeouts for unordered tagged commands.
1119	
1120	SCSI_NCR_CAN_QUEUE		(default: 7*SCSI_NCR_MAX_TAGS)
1121		Max number of commands that can be queued to a host.
1122	
1123	SCSI_NCR_CMD_PER_LUN		(default: SCSI_NCR_MAX_TAGS)
1124		Max number of commands queued to a host for a device.
1125	
1126	SCSI_NCR_SG_TABLESIZE		(default: SCSI_NCR_MAX_SCATTER-1)
1127		Max size of the Linux scatter/gather list.
1128	
1129	SCSI_NCR_MAX_LUN	(default: 8)
1130		Max number of LUNs per target.
1131	
1132	
1133	12. Installation
1134	
1135	This driver is part of the linux kernel distribution.
1136	Driver files are located in the sub-directory "drivers/scsi" of the 
1137	kernel source tree.
1138	
1139	Driver files:
1140	
1141		README.ncr53c8xx	: this file
1142		ChangeLog.ncr53c8xx	: change log
1143		ncr53c8xx.h		: definitions
1144		ncr53c8xx.c		: the driver code
1145	
1146	New driver versions are made available separately in order to allow testing 
1147	changes and new features prior to including them into the linux kernel 
1148	distribution. The following URL provides information on latest available 
1149	patches: 
1150	
1151	      ftp://ftp.tux.org/pub/people/gerard-roudier/README
1152	
1153	
1154	13. Architecture dependent features.
1155	
1156	<Not yet written>
1157	
1158	
1159	14. Known problems
1160	
1161	14.1 Tagged commands with Iomega Jaz device
1162	
1163	I have not tried this device, however it has been reported to me the
1164	following: This device is capable of Tagged command queuing. However
1165	while spinning up, it rejects Tagged commands. This behaviour is
1166	conforms to 6.8.2 of SCSI-2 specifications. The current behaviour of
1167	the driver in that situation is not satisfying. So do not enable
1168	Tagged command queuing for devices that are able to spin down.  The
1169	other problem that may appear is timeouts. The only way to avoid
1170	timeouts seems to edit linux/drivers/scsi/sd.c and to increase the
1171	current timeout values.
1172	
1173	14.2 Device names change when another controller is added.
1174	
1175	When you add a new NCR53C8XX chip based controller to a system that already 
1176	has one or more controllers of this family, it may happen that the order 
1177	the driver registers them to the kernel causes problems due to device 
1178	name changes.
1179	When at least one controller uses NvRAM, SDMS BIOS version 4 allows you to 
1180	define the order the BIOS will scan the scsi boards. The driver attaches 
1181	controllers according to BIOS information if NvRAM detect option is set.
1182	
1183	If your controllers do not have NvRAM, you can:
1184	
1185	- Ask the driver to probe chip ids in reverse order from the boot command
1186	  line: ncr53c8xx=revprob:y
1187	- Make appropriate changes in the fstab.
1188	- Use the 'scsidev' tool from Eric Youngdale.
1189	
1190	14.3 Using only 8 bit devices with a WIDE SCSI controller.
1191	
1192	When only 8 bit NARROW devices are connected to a 16 bit WIDE SCSI controller, 
1193	you must ensure that lines of the wide part of the SCSI BUS are pulled-up.
1194	This can be achieved by ENABLING the WIDE TERMINATOR portion of the SCSI 
1195	controller card.
1196	The TYAN 1365 documentation revision 1.2 is not correct about such settings.
1197	(page 10, figure 3.3).
1198	
1199	14.4 Possible data corruption during a Memory Write and Invalidate
1200	
1201	This problem is described in SYMBIOS DEL 397, Part Number 69-039241, ITEM 4.
1202	
1203	In some complex situations, 53C875 chips revision <= 3 may start a PCI 
1204	Write and Invalidate Command at a not cache-line-aligned 4 DWORDS boundary.
1205	This is only possible when Cache Line Size is 8 DWORDS or greater.
1206	Pentium systems use a 8 DWORDS cache line size and so are concerned by 
1207	this chip bug, unlike i486 systems that use a 4 DWORDS cache line size.
1208	
1209	When this situation occurs, the chip may complete the Write and Invalidate 
1210	command after having only filled part of the last cache line involved in 
1211	the transfer, leaving to data corruption the remainder of this cache line.
1212	
1213	Not using Write And Invalidate obviously gets rid of this chip bug, and so 
1214	it is now the default setting of the driver.
1215	However, for people like me who want to enable this feature, I have added 
1216	part of a work-around suggested by SYMBIOS. This work-around resets the 
1217	addressing logic when the DATA IN phase is entered and so prevents the bug 
1218	from being triggered for the first SCSI MOVE of the phase. This work-around 
1219	should be enough according to the following:
1220	
1221	The only driver internal data structure that is greater than 8 DWORDS  and 
1222	that is moved by the SCRIPTS processor is the 'CCB header' that contains 
1223	the context of the SCSI transfer. This data structure is aligned on 8 DWORDS 
1224	boundary (Pentium Cache Line Size), and so is immune to this chip bug, at 
1225	least on Pentium systems.
1226	But the conditions of this bug can be met when a SCSI read command is 
1227	performed using a buffer that is 4 DWORDS but not cache-line aligned.
1228	This cannot happen under Linux when scatter/gather lists are used since 
1229	they only refer to system buffers that are well aligned. So, a work around 
1230	may only be needed under Linux when a scatter/gather list is not used and 
1231	when the SCSI DATA IN phase is reentered after a phase mismatch.
1232	
1233	15. SCSI problem troubleshooting
1234	
1235	15.1 Problem tracking
1236	
1237	Most SCSI problems are due to a non conformant SCSI bus or to buggy
1238	devices.  If unfortunately you have SCSI problems, you can check the
1239	following things:
1240	
1241	- SCSI bus cables
1242	- terminations at both end of the SCSI chain
1243	- linux syslog messages (some of them may help you)
1244	
1245	If you do not find the source of problems, you can configure the
1246	driver with no features enabled.
1247	
1248	- only asynchronous data transfers
1249	- tagged commands disabled
1250	- disconnections not allowed
1251	
1252	Now, if your SCSI bus is ok, your system have every chance to work
1253	with this safe configuration but performances will not be optimal.
1254	
1255	If it still fails, then you can send your problem description to
1256	appropriate mailing lists or news-groups.  Send me a copy in order to
1257	be sure I will receive it.  Obviously, a bug in the driver code is
1258	possible.
1259	
1260	     My email address: Gerard Roudier <groudier@free.fr>
1261	
1262	Allowing disconnections is important if you use several devices on
1263	your SCSI bus but often causes problems with buggy devices.
1264	Synchronous data transfers increases throughput of fast devices like
1265	hard disks.  Good SCSI hard disks with a large cache gain advantage of
1266	tagged commands queuing.
1267	
1268	Try to enable one feature at a time with control commands.  For example:
1269	
1270	- echo "setsync all 25" >/proc/scsi/ncr53c8xx/0
1271	  Will enable fast synchronous data transfer negotiation for all targets.
1272	
1273	- echo "setflag 3" >/proc/scsi/ncr53c8xx/0
1274	  Will reset flags (no_disc) for target 3, and so will allow it to disconnect 
1275	  the SCSI Bus.
1276	
1277	- echo "settags 3 8" >/proc/scsi/ncr53c8xx/0
1278	  Will enable tagged command queuing for target 3 if that device supports it.
1279	
1280	Once you have found the device and the feature that cause problems, just 
1281	disable that feature for that device.
1282	
1283	15.2 Understanding hardware error reports
1284	
1285	When the driver detects an unexpected error condition, it may display a 
1286	message of the following pattern.
1287	
1288	sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
1289	sym53c876-0: script cmd = 19000000
1290	sym53c876-0: regdump: da 10 80 95 47 0f 01 07 75 01 81 21 80 01 09 00.
1291	
1292	Some fields in such a message may help you understand the cause of the 
1293	problem, as follows:
1294	
1295	sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
1296	............A.........B.C....D.E..F....G.H.......I.....J...K.......
1297	
1298	Field A : target number.
1299	  SCSI ID of the device the controller was talking with at the moment the 
1300	  error occurs.
1301	
1302	Field B : DSTAT io register (DMA STATUS)
1303	  Bit 0x40 : MDPE Master Data Parity Error
1304	             Data parity error detected on the PCI BUS.
1305	  Bit 0x20 : BF   Bus Fault
1306	             PCI bus fault condition detected
1307	  Bit 0x01 : IID  Illegal Instruction Detected
1308	             Set by the chip when it detects an Illegal Instruction format 
1309	             on some condition that makes an instruction illegal.
1310	  Bit 0x80 : DFE Dma Fifo Empty
1311	             Pure status bit that does not indicate an error.
1312	  If the reported DSTAT value contains a combination of MDPE (0x40), 
1313	  BF (0x20), then the cause may be likely due to a PCI BUS problem.
1314	
1315	Field C : SIST io register (SCSI Interrupt Status)
1316	  Bit 0x08 : SGE  SCSI GROSS ERROR
1317	             Indicates that the chip detected a severe error condition 
1318	             on the SCSI BUS that prevents the SCSI protocol from functioning
1319	             properly.
1320	  Bit 0x04 : UDC  Unexpected Disconnection
1321	             Indicates that the device released the SCSI BUS when the chip 
1322	             was not expecting this to happen. A device may behave so to 
1323	             indicate the SCSI initiator that an error condition not reportable              using the SCSI protocol has occurred.
1324	  Bit 0x02 : RST  SCSI BUS Reset
1325	             Generally SCSI targets do not reset the SCSI BUS, although any 
1326	             device on the BUS can reset it at any time.
1327	  Bit 0x01 : PAR  Parity
1328	             SCSI parity error detected.
1329	  On a faulty SCSI BUS, any error condition among SGE (0x08), UDC (0x04) and 
1330	  PAR (0x01) may be detected by the chip. If your SCSI system sometimes 
1331	  encounters such error conditions, especially SCSI GROSS ERROR, then a SCSI 
1332	  BUS problem is likely the cause of these errors.
1333	
1334	For fields D,E,F,G and H, you may look into the sym53c8xx_defs.h file 
1335	that contains some minimal comments on IO register bits.
1336	Field D : SOCL  Scsi Output Control Latch
1337	          This register reflects the state of the SCSI control lines the 
1338	          chip want to drive or compare against.
1339	Field E : SBCL  Scsi Bus Control Lines
1340	          Actual value of control lines on the SCSI BUS.
1341	Field F : SBDL  Scsi Bus Data Lines
1342	          Actual value of data lines on the SCSI BUS.
1343	Field G : SXFER  SCSI Transfer
1344	          Contains the setting of the Synchronous Period for output and 
1345	          the current Synchronous offset (offset 0 means asynchronous).
1346	Field H : SCNTL3 Scsi Control Register 3
1347	          Contains the setting of timing values for both asynchronous and 
1348	          synchronous data transfers. 
1349	
1350	Understanding Fields I, J, K and dumps requires to have good knowledge of 
1351	SCSI standards, chip cores functionnals and internal driver data structures.
1352	You are not required to decode and understand them, unless you want to help 
1353	maintain the driver code.
1354	
1355	16. Synchronous transfer negotiation tables
1356	
1357	Tables below have been created by calling the routine the driver uses
1358	for synchronisation negotiation timing calculation and chip setting.
1359	The first table corresponds to Ultra chips 53875 and 53C860 with 80 MHz 
1360	clock and 5 clock divisors.
1361	The second one has been calculated by setting the scsi clock to 40 Mhz 
1362	and using 4 clock divisors and so applies to all NCR53C8XX chips in fast 
1363	SCSI-2 mode.
1364	
1365	Periods are in nano-seconds and speeds are in Mega-transfers per second.
1366	1 Mega-transfers/second means 1 MB/s with 8 bits SCSI and 2 MB/s with 
1367	Wide16 SCSI.
1368	
1369	16.1 Synchronous timings for 53C895, 53C875 and 53C860 SCSI controllers
1370	
1371	 ----------------------------------------------
1372	 Negotiated                     NCR settings
1373	 Factor   Period   Speed        Period   Speed
1374	 ------   ------   ------       ------   ------
1375	 10       25       40.000       25       40.000   (53C895 only)
1376	 11       30.2     33.112       31.25    32.000   (53C895 only)
1377	 12       50       20.000       50       20.000
1378	 13       52       19.230       62       16.000
1379	 14       56       17.857       62       16.000
1380	 15       60       16.666       62       16.000
1381	 16       64       15.625       75       13.333
1382	 17       68       14.705       75       13.333
1383	 18       72       13.888       75       13.333
1384	 19       76       13.157       87       11.428
1385	 20       80       12.500       87       11.428
1386	 21       84       11.904       87       11.428
1387	 22       88       11.363       93       10.666
1388	 23       92       10.869       93       10.666
1389	 24       96       10.416      100       10.000
1390	 25      100       10.000      100       10.000
1391	 26      104        9.615      112        8.888
1392	 27      108        9.259      112        8.888
1393	 28      112        8.928      112        8.888
1394	 29      116        8.620      125        8.000
1395	 30      120        8.333      125        8.000
1396	 31      124        8.064      125        8.000
1397	 32      128        7.812      131        7.619
1398	 33      132        7.575      150        6.666
1399	 34      136        7.352      150        6.666
1400	 35      140        7.142      150        6.666
1401	 36      144        6.944      150        6.666
1402	 37      148        6.756      150        6.666
1403	 38      152        6.578      175        5.714
1404	 39      156        6.410      175        5.714
1405	 40      160        6.250      175        5.714
1406	 41      164        6.097      175        5.714
1407	 42      168        5.952      175        5.714
1408	 43      172        5.813      175        5.714
1409	 44      176        5.681      187        5.333
1410	 45      180        5.555      187        5.333
1411	 46      184        5.434      187        5.333
1412	 47      188        5.319      200        5.000
1413	 48      192        5.208      200        5.000
1414	 49      196        5.102      200        5.000
1415	
1416	
1417	16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
1418	
1419	 ----------------------------------------------
1420	 Negotiated                     NCR settings
1421	 Factor   Period   Speed        Period   Speed
1422	 ------   ------   ------       ------   ------
1423	 25      100       10.000      100       10.000
1424	 26      104        9.615      125        8.000
1425	 27      108        9.259      125        8.000
1426	 28      112        8.928      125        8.000
1427	 29      116        8.620      125        8.000
1428	 30      120        8.333      125        8.000
1429	 31      124        8.064      125        8.000
1430	 32      128        7.812      131        7.619
1431	 33      132        7.575      150        6.666
1432	 34      136        7.352      150        6.666
1433	 35      140        7.142      150        6.666
1434	 36      144        6.944      150        6.666
1435	 37      148        6.756      150        6.666
1436	 38      152        6.578      175        5.714
1437	 39      156        6.410      175        5.714
1438	 40      160        6.250      175        5.714
1439	 41      164        6.097      175        5.714
1440	 42      168        5.952      175        5.714
1441	 43      172        5.813      175        5.714
1442	 44      176        5.681      187        5.333
1443	 45      180        5.555      187        5.333
1444	 46      184        5.434      187        5.333
1445	 47      188        5.319      200        5.000
1446	 48      192        5.208      200        5.000
1447	 49      196        5.102      200        5.000
1448	
1449	
1450	17. Serial NVRAM (added by Richard Waltham: dormouse@farsrobt.demon.co.uk)
1451	
1452	17.1 Features
1453	
1454	Enabling serial NVRAM support enables detection of the serial NVRAM included
1455	on Symbios and some Symbios compatible host adaptors, and Tekram boards. The 
1456	serial NVRAM is used by Symbios and Tekram to hold set up parameters for the 
1457	host adaptor and its attached drives.
1458	
1459	The Symbios NVRAM also holds data on the boot order of host adaptors in a
1460	system with more than one host adaptor. This enables the order of scanning
1461	the cards for drives to be changed from the default used during host adaptor
1462	detection.
1463	
1464	This can be done to a limited extent at the moment using "reverse probe" but
1465	this only changes the order of detection of different types of cards. The
1466	NVRAM boot order settings can do this as well as change the order the same
1467	types of cards are scanned in, something "reverse probe" cannot do.
1468	
1469	Tekram boards using Symbios chips, DC390W/F/U, which have NVRAM are detected
1470	and this is used to distinguish between Symbios compatible and Tekram host 
1471	adaptors. This is used to disable the Symbios compatible "diff" setting
1472	incorrectly set on Tekram boards if the CONFIG_SCSI_53C8XX_SYMBIOS_COMPAT 
1473	configuration parameter is set enabling both Symbios and Tekram boards to be 
1474	used together with the Symbios cards using all their features, including
1475	"diff" support. ("led pin" support for Symbios compatible cards can remain
1476	enabled when using Tekram cards. It does nothing useful for Tekram host
1477	adaptors but does not cause problems either.)
1478	
1479	
1480	17.2 Symbios NVRAM layout
1481	
1482	typical data at NVRAM address 0x100 (53c810a NVRAM)
1483	-----------------------------------------------------------
1484	00 00
1485	64 01
1486	8e 0b
1487	
1488	00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00 
1489	
1490	04 00 0f 00 00 10 00 50 00 00 01 00 00 62 
1491	04 00 03 00 00 10 00 58 00 00 01 00 00 63 
1492	04 00 01 00 00 10 00 48 00 00 01 00 00 61 
1493	00 00 00 00 00 00 00 00 00 00 00 00 00 00 
1494	
1495	0f 00 08 08 64 00 0a 00
1496	0f 00 08 08 64 00 0a 00 
1497	0f 00 08 08 64 00 0a 00 
1498	0f 00 08 08 64 00 0a 00 
1499	0f 00 08 08 64 00 0a 00 
1500	0f 00 08 08 64 00 0a 00 
1501	0f 00 08 08 64 00 0a 00 
1502	0f 00 08 08 64 00 0a 00 
1503	
1504	0f 00 08 08 64 00 0a 00 
1505	0f 00 08 08 64 00 0a 00 
1506	0f 00 08 08 64 00 0a 00 
1507	0f 00 08 08 64 00 0a 00 
1508	0f 00 08 08 64 00 0a 00 
1509	0f 00 08 08 64 00 0a 00 
1510	0f 00 08 08 64 00 0a 00 
1511	0f 00 08 08 64 00 0a 00 
1512	
1513	00 00 00 00 00 00 00 00 
1514	00 00 00 00 00 00 00 00 
1515	00 00 00 00 00 00 00 00 
1516	00 00 00 00 00 00 00 00 
1517	00 00 00 00 00 00 00 00 
1518	00 00 00 00 00 00 00 00 
1519	00 00 00 00 00 00 00 00 
1520	00 00 00 00 00 00 00 00 
1521	
1522	00 00 00 00 00 00 00 00 
1523	00 00 00 00 00 00 00 00 
1524	00 00 00 00 00 00 00 00 
1525	00 00 00 00 00 00 00 00 
1526	00 00 00 00 00 00 00 00 
1527	00 00 00 00 00 00 00 00 
1528	00 00 00 00 00 00 00 00 
1529	00 00 00 00 00 00 00 00 
1530	
1531	00 00 00 00 00 00 00 00 
1532	00 00 00 00 00 00 00 00 
1533	00 00 00 00 00 00 00 00 
1534	
1535	fe fe
1536	00 00
1537	00 00
1538	-----------------------------------------------------------
1539	NVRAM layout details
1540	
1541	NVRAM Address 0x000-0x0ff not used
1542	              0x100-0x26f initialised data
1543	              0x270-0x7ff not used
1544	
1545	general layout
1546	
1547	        header  -   6 bytes,
1548	        data    - 356 bytes (checksum is byte sum of this data)
1549	        trailer -   6 bytes
1550	                  ---
1551	        total     368 bytes
1552	
1553	data area layout
1554	
1555	        controller set up  -  20 bytes
1556	        boot configuration -  56 bytes (4x14 bytes)
1557	        device set up      - 128 bytes (16x8 bytes)
1558	        unused (spare?)    - 152 bytes (19x8 bytes)
1559	                             ---
1560	        total                356 bytes
1561	
1562	-----------------------------------------------------------
1563	header
1564	
1565	00 00   - ?? start marker
1566	64 01   - byte count (lsb/msb excludes header/trailer)
1567	8e 0b   - checksum (lsb/msb excludes header/trailer)
1568	-----------------------------------------------------------
1569	controller set up
1570	
1571	00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00
1572	                   |     |           |     |
1573	                   |     |           |      -- host ID
1574	                   |     |           |
1575	                   |     |            --Removable Media Support
1576	                   |     |               0x00 = none
1577	                   |     |               0x01 = Bootable Device
1578	                   |     |               0x02 = All with Media
1579	                   |     |
1580	                   |      --flag bits 2
1581	                   |        0x00000001= scan order hi->low
1582	                   |            (default 0x00 - scan low->hi)
1583	                    --flag bits 1
1584	                       0x00000001 scam enable
1585	                       0x00000010 parity enable
1586	                       0x00000100 verbose boot msgs
1587	
1588	remaining bytes unknown - they do not appear to change in my
1589	current set up for any of the controllers.
1590	
1591	default set up is identical for 53c810a and 53c875 NVRAM
1592	(Removable Media added Symbios BIOS version 4.09)
1593	-----------------------------------------------------------
1594	boot configuration
1595	
1596	boot order set by order of the devices in this table
1597	
1598	04 00 0f 00 00 10 00 50 00 00 01 00 00 62 -- 1st controller
1599	04 00 03 00 00 10 00 58 00 00 01 00 00 63    2nd controller
1600	04 00 01 00 00 10 00 48 00 00 01 00 00 61    3rd controller
1601	00 00 00 00 00 00 00 00 00 00 00 00 00 00    4th controller
1602	       |  |  |  |     |        |     |  |
1603	       |  |  |  |     |        |      ---- PCI io port adr
1604	       |  |  |  |     |         --0x01 init/scan at boot time
1605	       |  |  |  |      --PCI device/function number (0xdddddfff)
1606	       |  |   ----- ?? PCI vendor ID (lsb/msb)
1607	        ----PCI device ID (lsb/msb)
1608	
1609	?? use of this data is a guess but seems reasonable
1610	
1611	remaining bytes unknown - they do not appear to change in my
1612	current set up
1613	
1614	default set up is identical for 53c810a and 53c875 NVRAM
1615	-----------------------------------------------------------
1616	device set up (up to 16 devices - includes controller)
1617	
1618	0f 00 08 08 64 00 0a 00 - id 0
1619	0f 00 08 08 64 00 0a 00 
1620	0f 00 08 08 64 00 0a 00 
1621	0f 00 08 08 64 00 0a 00 
1622	0f 00 08 08 64 00 0a 00 
1623	0f 00 08 08 64 00 0a 00 
1624	0f 00 08 08 64 00 0a 00 
1625	0f 00 08 08 64 00 0a 00 
1626	
1627	0f 00 08 08 64 00 0a 00 
1628	0f 00 08 08 64 00 0a 00 
1629	0f 00 08 08 64 00 0a 00 
1630	0f 00 08 08 64 00 0a 00 
1631	0f 00 08 08 64 00 0a 00 
1632	0f 00 08 08 64 00 0a 00 
1633	0f 00 08 08 64 00 0a 00 
1634	0f 00 08 08 64 00 0a 00 - id 15
1635	 |     |  |  |     |  |
1636	 |     |  |  |      ----timeout (lsb/msb)
1637	 |     |  |   --synch period (0x?? 40 Mtrans/sec- fast 40) (probably 0x28)
1638	 |     |  |                  (0x30 20 Mtrans/sec- fast 20)
1639	 |     |  |                  (0x64 10 Mtrans/sec- fast )
1640	 |     |  |                  (0xc8  5 Mtrans/sec)
1641	 |     |  |                  (0x00  asynchronous)
1642	 |     |   -- ?? max sync offset (0x08 in NVRAM on 53c810a) 
1643	 |     |                         (0x10 in NVRAM on 53c875)
1644	 |      --device bus width (0x08 narrow)
1645	 |                         (0x10 16 bit wide)
1646	  --flag bits
1647	    0x00000001 - disconnect enabled
1648	    0x00000010 - scan at boot time
1649	    0x00000100 - scan luns
1650	    0x00001000 - queue tags enabled
1651	
1652	remaining bytes unknown - they do not appear to change in my
1653	current set up
1654	
1655	?? use of this data is a guess but seems reasonable 
1656	(but it could be max bus width)
1657	
1658	default set up for 53c810a NVRAM
1659	default set up for 53c875 NVRAM - bus width     - 0x10
1660	                                - sync offset ? - 0x10
1661	                                - sync period   - 0x30
1662	-----------------------------------------------------------
1663	?? spare device space (32 bit bus ??)
1664	
1665	00 00 00 00 00 00 00 00  (19x8bytes)
1666	.
1667	.
1668	00 00 00 00 00 00 00 00
1669	
1670	default set up is identical for 53c810a and 53c875 NVRAM
1671	-----------------------------------------------------------
1672	trailer
1673	
1674	fe fe   - ? end marker ?
1675	00 00
1676	00 00
1677	
1678	default set up is identical for 53c810a and 53c875 NVRAM
1679	-----------------------------------------------------------
1680	
1681	
1682	
1683	17.3 Tekram NVRAM layout
1684	
1685	nvram 64x16 (1024 bit)
1686	
1687	Drive settings
1688	
1689	Drive ID 0-15 (addr 0x0yyyy0 = device setup, yyyy = ID)
1690	              (addr 0x0yyyy1 = 0x0000)
1691	
1692	    x x x x  x x x x  x x x x  x x x x
1693	               | | |      | |  | | | |
1694	               | | |      | |  | | |  ----- parity check   0 - off
1695	               | | |      | |  | | |                       1 - on
1696	               | | |      | |  | | |
1697	               | | |      | |  | |  ------- sync neg       0 - off
1698	               | | |      | |  | |                         1 - on
1699	               | | |      | |  | |
1700	               | | |      | |  |  --------- disconnect     0 - off
1701	               | | |      | |  |                           1 - on
1702	               | | |      | |  |
1703	               | | |      | |   ----------- start cmd      0 - off
1704	               | | |      | |                              1 - on
1705	               | | |      | |
1706	               | | |      |  -------------- tagged cmds    0 - off
1707	               | | |      |                                1 - on
1708	               | | |      | 
1709	               | | |       ---------------- wide neg       0 - off
1710	               | | |                                       1 - on
1711	               | | |
1712	                --------------------------- sync rate      0 - 10.0 Mtrans/sec
1713	                                                           1 -  8.0
1714	                                                           2 -  6.6
1715	                                                           3 -  5.7
1716	                                                           4 -  5.0
1717	                                                           5 -  4.0
1718	                                                           6 -  3.0
1719	                                                           7 -  2.0
1720	                                                           7 -  2.0
1721	                                                           8 - 20.0
1722	                                                           9 - 16.7
1723	                                                           a - 13.9
1724	                                                           b - 11.9
1725	
1726	Global settings
1727	
1728	Host flags 0 (addr 0x100000, 32) 
1729	
1730	    x x x x  x x x x  x x x x  x x x x
1731	    | | | |  | | | |           | | | |
1732	    | | | |  | | | |            ----------- host ID    0x00 - 0x0f
1733	    | | | |  | | | |
1734	    | | | |  | | |  ----------------------- support for    0 - off
1735	    | | | |  | | |                          > 2 drives     1 - on
1736	    | | | |  | | | 
1737	    | | | |  | |  ------------------------- support drives 0 - off
1738	    | | | |  | |                            > 1Gbytes      1 - on
1739	    | | | |  | |
1740	    | | | |  |  --------------------------- bus reset on   0 - off
1741	    | | | |  |                                power on     1 - on
1742	    | | | |  |
1743	    | | | |   ----------------------------- active neg     0 - off
1744	    | | | |                                                1 - on
1745	    | | | |
1746	    | | |  -------------------------------- imm seek       0 - off
1747	    | | |                                                  1 - on
1748	    | | |
1749	    | |  ---------------------------------- scan luns      0 - off
1750	    | |                                                    1 - on
1751	    | |
1752	     -------------------------------------- removable      0 - disable
1753	                                            as BIOS dev    1 - boot device
1754	                                                           2 - all
1755	
1756	Host flags 1 (addr 0x100001, 33)
1757	
1758	    x x x x  x x x x  x x x x  x x x x
1759	               | | |             | | | 
1760	               | | |              --------- boot delay     0 -   3 sec
1761	               | | |                                       1 -   5
1762	               | | |                                       2 -  10
1763	               | | |                                       3 -  20
1764	               | | |                                       4 -  30
1765	               | | |                                       5 -  60
1766	               | | |                                       6 - 120
1767	               | | |
1768	                --------------------------- max tag cmds   0 -  2
1769	                                                           1 -  4
1770	                                                           2 -  8
1771	                                                           3 - 16
1772	                                                           4 - 32
1773	
1774	Host flags 2 (addr 0x100010, 34)
1775	
1776	    x x x x  x x x x  x x x x  x x x x
1777	                                     |
1778	                                      ----- F2/F6 enable   0 - off ???
1779	                                                           1 - on  ???
1780	
1781	checksum (addr 0x111111)
1782	
1783	checksum = 0x1234 - (sum addr 0-63)
1784	
1785	----------------------------------------------------------------------------
1786	
1787	default nvram data:
1788	
1789	0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
1790	0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
1791	0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
1792	0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 
1793	
1794	0x0f07 0x0400 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000
1795	0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
1796	0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
1797	0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0xfbbc
1798	
1799	
1800	18. Support for Big Endian
1801	
1802	The PCI local bus has been primarily designed for x86 architecture.
1803	As a consequence, PCI devices generally expect DWORDS using little endian 
1804	byte ordering.
1805	
1806	18.1 Big Endian CPU
1807	
1808	In order to support NCR chips on a Big Endian architecture the driver has to 
1809	perform byte reordering each time it is needed. This feature has been 
1810	added to the driver by Cort <cort@cs.nmt.edu> and is available in driver 
1811	version 2.5 and later ones. For the moment Big Endian support has only 
1812	been tested on Linux/PPC (PowerPC).
1813	
1814	18.2 NCR chip in Big Endian mode of operations
1815	
1816	It can be read in SYMBIOS documentation that some chips support a special 
1817	Big Endian mode, on paper: 53C815, 53C825A, 53C875, 53C875N, 53C895.
1818	This mode of operations is not software-selectable, but needs pin named 
1819	BigLit to be pulled-up. Using this mode, most of byte reorderings should 
1820	be avoided when the driver is running on a Big Endian CPU.
1821	Driver version 2.5 is also, in theory, ready for this feature.
1822	
1823	===============================================================================
1824	End of NCR53C8XX driver README file
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