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The Linux NCR53C8XX driver README file

Written by Gerard Roudier 

21 Rue Carnot

95170 DEUIL LA BARRE - FRANCE

13 December 1998

===============================================================================

1.  Introduction

2.  Supported chips and SCSI features

3.  Summary of other supported features

4.  Memory mapped I/O versus normal I/O

5.  Tagged command queueing

6.  Parity checking

7.  Profiling information

8.  Control commands

      8.1  Set minimum synchronous period

      8.2  Set wide size

      8.3  Set maximum number of concurrent tagged commands

      8.4  Set order type for tagged command

      8.5  Set debug mode

      8.6  Clear profile counters

      8.7  Set flag (no_disc)

      8.8  Set verbose level

9.  Configuration parameters

10. Boot setup commands

      10.1 Syntax

      10.2 Available arguments

      10.3 Advised boot setup commands

      10.4 PCI configuration fix-up boot option

      10.5 Serial NVRAM support boot option

      10.6 SCSI BUS checking boot option

11. Some constants and flags of the ncr53c8xx.h header file

12. Installation

13. Architecture dependant features

14. Known problems

      14.1 Tagged commands with Iomega Jaz device

      14.2 Device names change when another controller is added

      14.3 Using only 8 bit devices with a WIDE SCSI controller.

      14.4 Possible data corruption during a Memory Write and Invalidate

15. SCSI problem troubleshooting

16. Synchonous transfer negotiation tables

      16.1 Synchronous timings for 53C875 and 53C860 Ultra-SCSI controllers

      16.2 Synchronous timings for fast SCSI-2 53C8XX controllers

17. Serial NVRAM support (by Richard Waltham)

      17.1 Features

      17.2 Symbios NVRAM layout

      17.3 Tekram  NVRAM layout

18. Support for Big Endian

      18.1 Big Endian CPU

      18.2 NCR chip in Big Endian mode of operations

===============================================================================

1. Introduction

This driver has been ported from FreeBSD to Linux and is currently

maintained by:

          Gerard Roudier              

The original driver has been written for 386bsd and FreeBSD by:

          Wolfgang Stanglmeier        

          Stefan Esser                

You can find technical information about the NCR 8xx family in the

PCI-HOWTO written by Michael Will and in the SCSI-HOWTO written by

Drew Eckhardt.

Information about new chips is available at SYMBIOS web server:

          http://www.symbios.com/

SCSI standard documentations are available at SYMBIOS ftp server:

          ftp://ftp.symbios.com/

Usefull SCSI tools written by Eric Youngdale are available at tsx-11:

          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsiinfo-X.Y.tar.gz

          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsidev-X.Y.tar.gz

These tools are not ALPHA but quite clean and work quite well.

It is essential you have the 'scsiinfo' package.

This short documentation only describes the features of the NCR53C8XX

driver, configuration parameters and control commands available

through the proc SCSI file system read / write operations.

This driver has been tested OK with linux/i386, Linux/Alpha and Linux/PPC.

Latest driver version and patches are available at:

          ftp://ftp.tux.org/pub/people/gerard-roudier

I am not a native speaker of English and there are probably lots of

mistakes in this README file. Any help will be welcome.

2. Supported chips and SCSI features

The following features are supported for all chips:

        Synchronous negotiation

        Disconnection

        Tagged command queuing

        SCSI parity checking

        Master parity checking

"Wide negotiation" is supported for chips that allow it.  The

following table shows some characteristics of NCR 8xx family chips:

       On board                                  Supported by

Chip   SDMS BIOS   Wide   SCSI std.   Max. sync   the driver

----   ---------   ----   ---------   ----------  ------------

810        N         N      FAST10    10 MB/s        Y

810A       N         N      FAST10    10 MB/s        Y(2)

815        Y         N      FAST10    10 MB/s        Y

825        Y         Y      FAST10    20 MB/s        Y

825A       Y         Y      FAST10    20 MB/s        Y(2)

860        N         N      FAST20    20 MB/s        Y(2)

875        Y         Y      FAST20    40 MB/s        Y(2)

876        Y         Y      FAST20    40 MB/s        Y(2)

895        Y         Y      FAST40    80 MB/s        Y(2)

896        Y         Y      FAST40    80 MB/s        Y(1)

(1) The ncr53c8xx driver does not support the following features of

    the 896:

    - Hardware phase mismatch.

    - 8k on-chip RAM.

    If you have a 896 chip, you may want to use the enhanced sym53c8xx

    driver that supports all the features of the 896.

    The sym53c8xx driver is available at the following URL:

             ftp://ftp.tux.org/pub/roudier/896/

(2) Chip also supported by the sym53c8xx enhanced driver.

3. Summary of other supported features.

        Module:                allow to load the driver

        Memory mapped I/O:     increases performance

        Profiling information: read operations from the proc SCSI file system

        Control commands:      write operations to the proc SCSI file system

        Debugging information: written to syslog (expert only)

        Scatter / gather

        Shared interrupt

        Boot setup commands

        Serial NVRAM:          Symbios and Tekram formats

4. Memory mapped I/O versus normal I/O

Memory mapped I/O has less latency than normal I/O.  Since

linux-1.3.x, memory mapped I/O is used rather than normal I/O.  Memory

mapped I/O seems to work fine on most hardware configurations, but

some poorly designed motherboards may break this feature.

The configuration option CONFIG_SCSI_NCR53C8XX_IOMAPPED forces the

driver to use normal I/O in all cases.

5. Tagged command queueing

Queuing more than 1 command at a time to a device allows it to perform

optimizations based on actual head positions and its mechanical

characteristics. This feature may also reduce average command latency.

In order to really gain advantage of this feature, devices must have

a reasonnable cache size (No miracle is to be expected for a low-end

hard disk with 128 KB or less).

Some kown SCSI devices do not properly support tagged command queuing.

Generally, firmware revisions that fix this kind of problems are available

at respective vendor web/ftp sites.

All I can say is that the hard disks I use on my machines behave well with

this driver with tagged command queuing enabled:

- IBM S12 0662

- Conner 1080S

- Quantum Atlas I

- Quantum Atlas II

If your controller has NVRAM, you can configure this feature per target

from the user setup tool. The Tekram Setup program allows to tune the

maximum number of queued commands up to 32. The Symbios Setup only allows

to enable or disable this feature.

The maximum number of simultaneous tagged commands queued to a device

is currently set to 8 by default.  This value is suitable for most SCSI

disks.  With large SCSI disks (>= 2GB, cache >= 512KB, average seek time

<= 10 ms), using a larger value may give better performances.

The driver supports up to 64 commands per device, but using more than

32 is generally not worth it, unless you are using a very large disk

or disk array.

If your controller does not have NVRAM or if it is managed by the SDMS

BIOS/SETUP, you can configure tagged queueing feature and device queue

depths from the boot command-line. For example:

  ncr53c8xx=tags:4/t2t3q15-t4q7/t1u0q32

will set tagged commands queue depths as follow:

- target 2  all luns  on controller 0 --> 15

- target 3  all luns  on controller 0 --> 15

- target 4  all luns  on controller 0 -->  7

- target 1  lun 0     on controller 1 --> 32

- all other target/lun                -->  4

In some special conditions, some SCSI disk firmwares may return a

QUEUE FULL status for a SCSI command. This behaviour is managed by the

driver using the following heuristic:

- Each time a QUEUE FULL status is returned, tagged queue depth is reduced

  to the actual number of disconnected commands.

- Every 1000 successfully completed SCSI commands, if allowed by the

  current limit, the maximum number of queueable commands is incremented.

Since QUEUE FULL status reception and handling is resource wasting, the

driver notifies by default this problem to user by indicating the actual

number of commands used and their status, as well as its decision on the

device queue depth change.

The heuristic used by the driver in handling QUEUE FULL ensures that the

impact on performances is not too bad. You can get rid of the messages by

setting verbose level to zero, as follow:

1st method: boot your system using 'ncr53c8xx=verb:0' option.

2nd method: apply "setverbose 0" control command to the proc fs entry

            corresponding to your controller after boot-up.

6. Parity checking

The driver supports SCSI parity checking and PCI bus master parity

checking.  These features must be enabled in order to ensure safe data

transfers.  However, some flawed devices or mother boards will have

problems with parity. You can disable either PCI parity or SCSI parity

checking by entering appropriate options from the boot command line.

(See 10: Boot setup commands).

7. Profiling information

Profiling information is available through the proc SCSI file system.

Since gathering profiling information may impact performances, this

feature is disabled by default and requires a compilation configuration

option to be set to Y.

The device associated with a host has the following pathname:

          /proc/scsi/ncr53c8xx/N     (N=0,1,2 ....)

Generally, only 1 board is used on hardware configuration, and that device is:

          /proc/scsi/ncr53c8xx/0

However, if the driver has been made as module, the number of the

hosts is incremented each time the driver is loaded.

In order to display profiling information, just enter:

         cat /proc/scsi/ncr53c8xx/0

and you will get something like the following text:

-------------------------------------------------------

General information:

  Chip NCR53C810, device id 0x1, revision id 0x2

  IO port address 0x6000, IRQ number 10

  Using memory mapped IO at virtual address 0x282c000

  Synchronous transfer period 25, max commands per lun 4

Profiling information:

  num_trans    = 18014

  num_kbytes   = 671314

  num_disc     = 25763

  num_break    = 1673

  num_int      = 1685

  num_fly      = 18038

  ms_setup     = 4940

  ms_data      = 369940

  ms_disc      = 183090

  ms_post      = 1320

-------------------------------------------------------

General information is easy to understand. The device ID and the

revision ID identify the SCSI chip as follows:

Chip    Device id     Revision Id

----    ---------     -----------

810       0x1            <  0x10

810A      0x1            >= 0x10

815       0x4

825       0x3            <  0x10

860       0x6

825A      0x3            >= 0x10

875       0xf

895       0xc

The profiling information is updated upon completion of SCSI commands.

A data structure is allocated and zeroed when the host adapter is

attached. So, if the driver is a module, the profile counters are

cleared each time the driver is loaded.  The "clearprof" command

allows you to clear these counters at any time.

The following counters are available:

("num" prefix means "number of",

"ms" means milli-seconds)

num_trans

        Number of completed commands

        Example above: 18014 completed commands

num_kbytes

        Number of kbytes transferred

        Example above: 671 MB transferred

num_disc

        Number of SCSI disconnections

        Example above: 25763 SCSI disconnections

num_break

        number of script interruptions (phase mismatch)

        Example above: 1673 script interruptions

num_int

        Number of interrupts other than "on the fly"

        Example above: 1685 interruptions not "on the fly"

num_fly

        Number of interrupts "on the fly"

        Example above: 18038 interruptions "on the fly"

ms_setup

        Elapsed time for SCSI commands setups

        Example above: 4.94 seconds

ms_data

        Elapsed time for data transfers

        Example above: 369.94 seconds spent for data transfer

ms_disc

        Elapsed time for SCSI disconnections

        Example above: 183.09 seconds spent disconnected

ms_post

        Elapsed time for command post processing

        (time from SCSI status get to command completion call)

        Example above: 1.32 seconds spent for post processing

Due to the 1/100 second tick of the system clock, "ms_post" time may

be wrong.

In the example above, we got 18038 interrupts "on the fly" and only

1673 script breaks generally due to disconnections inside a segment

of the scatter list.

8. Control commands

Control commands can be sent to the driver with write operations to

the proc SCSI file system. The generic command syntax is the

following:

      echo " " >/proc/scsi/ncr53c8xx/0

      (assumes controller number is 0)

Using "all" for "" parameter with the commands below will

apply to all targets of the SCSI chain (except the controller).

Available commands:

8.1 Set minimum synchronous period factor

    setsync  

    target:    target number

    period:    minimum synchronous period.

               Maximum speed = 1000/(4*period factor) except for special

               cases below.

    Specify a period of 255, to force asynchronous transfer mode.

      10 means 25 nano-seconds synchronous period

      11 means 30 nano-seconds synchronous period

      12 means 50 nano-seconds synchronous period

8.2 Set wide size

    setwide  

    target:    target number

    size:      0=8 bits, 1=16bits

8.3 Set maximum number of concurrent tagged commands

    settags  

    target:    target number

    tags:      number of concurrent tagged commands

               must not be greater than SCSI_NCR_MAX_TAGS (default: 8)

8.4 Set order type for tagged command

    setorder 

    order:     3 possible values:

               simple: use SIMPLE TAG for all operations (read and write)

               ordered: use ORDERED TAG for all operations

               default: use default tag type,

                        SIMPLE  TAG for read  operations

                        ORDERED TAG for write operations

8.5 Set debug mode

    setdebug 

    Available debug flags:

        alloc:   print info about memory allocations (ccb, lcb)

        queue:   print info about insertions into the command start queue

        result:  print sense data on CHECK CONDITION status

        scatter: print info about the scatter process

        scripts: print info about the script binding process

        tiny:    print minimal debugging information

        timing:  print timing information of the NCR chip

        nego:    print information about SCSI negotiations

        phase:   print information on script interruptions

    Use "setdebug" with no argument to reset debug flags.

8.6 Clear profile counters

    clearprof

    The profile counters are automatically cleared when the amount of

    data transfered reaches 1000 GB in order to avoid overflow.

    The "clearprof" command allows you to clear these counters at any time.

8.7 Set flag (no_disc)

    setflag  

    target:    target number

    For the moment, only one flag is available:

        no_disc:   not allow target to disconnect.

    Do not specify any flag in order to reset the flag. For example:

    - setflag 4

      will reset no_disc flag for target 4, so will allow it disconnections.

    - setflag all

      will allow disconnection for all devices on the SCSI bus.

8.8 Set verbose level

    setverbose #level

    The driver default verbose level is 1. This command allows to change

    th driver verbose level after boot-up.

9. Configuration parameters

If the firmware of all your devices is perfect enough, all the

features supported by the driver can be enabled at start-up.  However,

if only one has a flaw for some SCSI feature, you can disable the

support by the driver of this feature at linux start-up and enable

this feature after boot-up only for devices that support it safely.

CONFIG_SCSI_NCR53C8XX_PROFILE_SUPPORT  (default answer: n)

    This option must be set for profiling information to be gathered

    and printed out through the proc file system. This features may

    impact performances.

CONFIG_SCSI_NCR53C8XX_IOMAPPED       (default answer: n)

    Answer "y" if you suspect your mother board to not allow memory mapped I/O.

    May slow down performance a little.  This option is required by

    Linux/PPC and is used no matter what you select here.  Linux/PPC

    suffers no performance loss with this option since all IO is memory

    mapped anyway.

CONFIG_SCSI_NCR53C8XX_DEFAULT_TAGS    (default answer: 8)

    Default tagged command queue depth.

CONFIG_SCSI_NCR53C8XX_MAX_TAGS         (default answer: 8)

    This option allows you to specify the maximum number of tagged commands

    that can be queued to a device. The maximum supported value is 64.

CONFIG_SCSI_NCR53C8XX_SYNC            (default answer: 5)

    This option allows you to specify the frequency in MHz the driver

    will use at boot time for synchronous data transfer negotiations.

    This frequency can be changed later with the "setsync" control command.

CONFIG_SCSI_NCR53C8XX_FORCE_SYNC_NEGO (default answer: n)

    Force synchronous negotiation for all SCSI-2 devices.

    Some SCSI-2 devices do not report this feature in byte 7 of inquiry

    response but do support it properly (TAMARACK scanners for example).

CONFIG_SCSI_NCR53C8XX_NO_DISCONNECT   (default and only reasonnable answer: n)

    If you suspect a device of yours does not properly support disconnections,

    you can answer "y". Then, all SCSI devices will never disconnect the bus

    even while performing long SCSI operations.

CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT

    Genuine SYMBIOS boards use GPIO0 in output for controller LED and GPIO3

    bit as a flag indicating singled-ended/differential interface.

    If all the boards of your system are genuine SYMBIOS boards or use

    BIOS and drivers from SYMBIOS, you would want to enable this option.

    This option must NOT be enabled if your system has at least one 53C8XX

    based scsi board with a vendor-specific BIOS.

    For example, Tekram DC-390/U, DC-390/W and DC-390/F scsi controllers

    use a vendor-specific BIOS and are known to not use SYMBIOS compatible

    GPIO wiring. So, this option must not be enabled if your system has

    such a board installed.

CONFIG_SCSI_NCR53C8XX_NVRAM_DETECT

    Enable support for reading the serial NVRAM data on Symbios and

    some Symbios compatible cards, and Tekram DC390W/U/F cards. Useful for

    systems with more than one Symbios compatible controller where at least

    one has a serial NVRAM, or for a system with a mixture of Symbios and

    Tekram cards. Enables setting the boot order of host adaptors

    to something other than the default order or "reverse probe" order.

    Also enables Symbios and Tekram cards to be distinguished so

    CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT may be set in a system with a

    mixture of Symbios and Tekram cards so the Symbios cards can make use of

    the full range of Symbios features, differential, led pin, without

    causing problems for the Tekram card(s).

10. Boot setup commands

10.1 Syntax

Setup commands can be passed to the driver either at boot time or as a

string variable using 'insmod'.

A boot setup command for the ncr53c8xx driver begins with the driver name

"ncr53c8xx=". The kernel syntax parser then expects an optionnal list of

integers separated with comma followed by an optionnal list of  comma-

separated strings. Example of boot setup command under lilo prompt:

lilo: linux root=/dev/hda2 ncr53c8xx=tags:4,sync:10,debug:0x200

- enable tagged commands, up to 4 tagged commands queued.

- set synchronous negotiation speed to 10 Mega-transfers / second.

- set DEBUG_NEGO flag.

Since comma seems not to be allowed when defining a string variable using

'insmod', the driver also accepts  as option separator.

The following command will install driver module with the same options as

above.

insmod ncr53c8xx.o ncr53c8xx="tags:4 sync:10 debug:0x200"

For the moment, the integer list of arguments is discarded by the driver.

It will be used in the future in order to allow a per controller setup.

Each string argument must be specified as "keyword:value". Only lower-case

characters and digits are allowed.

10.2 Available arguments

Master parity checking

      mpar:y     enabled

      mpar:n     disabled

Scsi parity checking

      spar:y     enabled

      spar:n     disabled

Scsi disconnections

      disc:y     enabled

      disc:n     disabled

Special features

   Only apply to 810A, 825A, 860, 875 and 895 controllers.

   Have no effect with other ones.

      specf:y    (or 1) enabled

      specf:n    (or 0) disabled

      specf:3           enabled except Memory Write And Invalidate

   The default driver setup is 'specf:3'. As a consequence, option 'specf:y'

   must be specified in the boot setup command to enable Memory Write And

   Invalidate.

Ultra SCSI support

   Only apply to 860, 875 and 895 controllers.

   Have no effect with other ones.

      ultra:2    Ultra2 enabled

      ultra:1    Ultra enabled

      ultra:n    disabled

Default number of tagged commands

      tags:0     (or tags:1 ) tagged command queuing disabled

      tags:#tags (#tags  > 1) tagged command queuing enabled

  #tags will be truncated to the max queued commands configuration parameter.

  This option also allows to specify a command queue depth for each device

  that support tagged command queueing.

  Example:

      ncr53c8xx=tags:10/t2t3q16-t5q24/t1u2q32

               will set devices queue depth as follow:

      - controller #0 target #2 and target #3                  -> 16 commands,

      - controller #0 target #5                                -> 24 commands,

      - controller #1 target #1 logical unit #2                -> 32 commands,

      - all other logical units (all targets, all controllers) -> 10 commands.

Default synchronous period factor

      sync:255     disabled (asynchronous transfer mode)

      sync:#factor

  #factor = 10     Ultra-2 SCSI 40 Mega-transfers / second

  #factor = 11     Ultra-2 SCSI 33 Mega-transfers / second

  #factor < 25     Ultra   SCSI 20 Mega-transfers / second

  #factor < 50     Fast    SCSI-2

  In all cases, the driver will use the minimum transfer period supported by

  controllers according to NCR53C8XX chip type.

Negotiate synchronous with all devices

  (force sync nego)

      fsn:y      enabled

      fsn:n      disabled

Verbosity level

      verb:0     minimal

      verb:1     normal

      verb:2     too much

Debug mode

      debug:0    clear debug flags

      debug:#x   set debug flags

  #x is an integer value combining the following power-of-2 values:

  DEBUG_ALLOC       0x1

  DEBUG_PHASE       0x2

  DEBUG_POLL        0x4

  DEBUG_QUEUE       0x8

  DEBUG_RESULT     0x10

  DEBUG_SCATTER    0x20

  DEBUG_SCRIPT     0x40

  DEBUG_TINY       0x80

  DEBUG_TIMING    0x100

  DEBUG_NEGO      0x200

  DEBUG_TAGS      0x400

  DEBUG_FREEZE    0x800

  DEBUG_RESTART  0x1000

  You can play safely with DEBUG_NEGO. However, some of these flags may

  generate bunches of syslog messages.

Burst max

      burst:0    burst disabled

      burst:255  get burst length from initial IO register settings.

      burst:#x   burst enabled (1<<#x burst transfers max)

  #x is an integer value which is log base 2 of the burst transfers max.

  The NCR53C875 and NCR53C825A support up to 128 burst transfers (#x = 7).

  Other chips only support up to 16 (#x = 4).

  This is a maximum value. The driver set the burst length according to chip

  and revision ids. By default the driver uses the maximum value supported

  by the chip.

LED support

     led:1      enable  LED support

     led:0      disable LED support

  Donnot enable LED support if your scsi board does not use SDMS BIOS.

  (See 'Configuration parameters')

Max wide

    wide:1      wide scsi enabled

    wide:0      wide scsi disabled

  Some scsi boards use a 875 (ultra wide) and only supply narrow connectors.

  If you have connected a wide device with a 50 pins to 68 pins cable

  converter, any accepted wide negotiation will break further data transfers.

  In such a case, using "wide:0" in the bootup command will be helpfull.

Differential mode

    diff:0      never set up diff mode

    diff:1      set up diff mode if BIOS set it

    diff:2      always set up diff mode

    diff:3      set diff mode if GPIO3 is not set

IRQ mode

    irqm:0      always open drain

    irqm:1      same as initial settings (assumed BIOS settings)

    irqm:2      always totem pole

Reverse probe

    revprob:n   probe chip ids from the PCI configuration in this order:

                810, 815, 820, 860, 875, 885, 895, 896

    revprob:y   probe chip ids in the reverse order.

Fix up PCI configuration space

    pcifix:

    Available option bits:

        0x0:   No attempt to fix PCI configuration space registers values.

        0x1:   Set PCI cache-line size register if not set.

        0x2:   Set write and invalidate bit in PCI command register.

        0x4:   Increase if necessary PCI latency timer according to burst max.

    Use 'pcifix:7' in order to allow the driver to fix up all PCI features.

Serial NVRAM

    nvram:n     do not look for serial NVRAM

    nvram:y     test controllers for onboard serial NVRAM

Check SCSI BUS

    buschk:

    Available option bits:

        0x0:   No check.

        0x1:   Check and donnot attach the controller on error.

        0x2:   Check and just warn on error.

Boot fail safe

    safe:y      load the following assumed fail safe initial setup

  master parity                 disabled                mpar:n

  scsi parity                   enabled                 spar:y

  disconnections                not allowed             disc:n

  special features              disabled                specf:n

  ultra scsi                    disabled                ultra:n

  force sync negotiation        disabled                fsn:n

  reverse probe                 disabled                revprob:n

  PCI fix up                    disabled                pcifix:0

  serial NVRAM                  enabled                 nvram:y

  verbosity level               2                       verb:2

  tagged command queuing        disabled                tags:0

  synchronous negotiation       disabled                sync:255

  debug flags                   none                    debug:0

  burst length                  from BIOS settings      burst:255

  LED support                   disabled                led:0

  wide support                  disabled                wide:0

  settle time                   10 seconds              settle:10

  differential support          from BIOS settings      diff:1

  irq mode                      from BIOS settings      irqm:1

  SCSI BUS check                donnot attach on error  buschk:1

10.3 Advised boot setup commands

If the driver has been configured with default options, the equivalent

boot setup is:

   ncr53c8xx=mpar:y,spar:y,disc:y,specf:3,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\

             tags:0,sync:50,debug:0,burst:7,led:0,wide:1,settle:2,diff:0,irqm:0

For an installation diskette or a safe but not fast system,

boot setup can be:

    ncr53c8xx=safe:y,mpar:y,disc:y

    ncr53c8xx=safe:y,disc:y

    ncr53c8xx=safe:y,mpar:y

    ncr53c8xx=safe:y

My personnal system works flawlessly with the following equivalent setup:

   ncr53c8xx=mpar:y,spar:y,disc:y,specf:1,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\

             tags:32,sync:12,debug:0,burst:7,led:1,wide:1,settle:2,diff:0,irqm:0

The driver prints its actual setup when verbosity level is 2. You can try

"ncr53c8xx=verb:2" to get the "static" setup of the driver, or add "verb:2"

to your boot setup command in order to check the actual setup the driver is

using.

10.4 PCI configuration fix-up boot option

pcifix:

Available option bits:

    0x1:     Set PCI cache-line size register if not set.

    0x2:     Set write and invalidate bit in PCI command register.

Use 'pcifix:3' in order to allow the driver to fix both PCI features.

These options only apply to new SYMBIOS chips 810A, 825A, 860, 875

and 895 and are only supported for Pentium and 486 class processors.

Recent SYMBIOS 53C8XX scsi processors are able to use PCI read multiple

and PCI write and invalidate commands. These features require the

cache line size register to be properly set in the PCI configuration

space of the chips. On the other hand, chips will use PCI write and

invalidate commands only if the corresponding bit is set to 1 in the

PCI command register.

Not all PCI bioses set the PCI cache line register and the PCI write and

invalidate bit in the PCI configuration space of 53C8XX chips.

Optimized PCI accesses may be broken for some PCI/memory controllers or

make problems with some PCI boards.

This fix-up worked flawlessly on my previous system.

(MB Triton HX / 53C875 / 53C810A)

I use these options at my own risks as you will do if you decide to

use them too.

10.5 Serial NVRAM support boot option

nvram:n     do not look for serial NVRAM

nvram:y     test controllers for onboard serial NVRAM

This option is described below (see 17. Serial NVRAM support).

When this option is enabled, the driver tries to detect all boards using

a Serial NVRAM. This memory is used to hold user set up parameters.

The parameters the driver is able to get from the NVRAM depend on the

data format used, as follow:

                                 Tekram format      Symbios format

General and host parameters

    Boot order                         N                   Y

    Host SCSI ID                       Y                   Y

    SCSI parity checking               Y                   Y

    Verbose boot messages              N                   Y

SCSI devices parameters

    Synchronous transfer speed         Y                   Y

    Wide 16 / Narrow                   Y                   Y

    Tagged Command Queuing enabled     Y                   Y

    Disconnections enabled             Y                   Y

    Scan at boot time                  N                   Y

In order to speed up the system boot, for each device configured without

the "scan at boot time" option, the driver forces an error on the

first TEST UNIT READY command received for this device.

Some SDMS BIOS revisions seem to be unable to boot cleanly with very fast

hard disks. In such a situation you cannot configure the NVRAM with

optimized parameters value.

The 'nvram' boot option can be entered in hexadecimal form in order

to ignore some options configured in the NVRAM, as follow:

mvram=

      0x01   look for NVRAM  (equivalent to nvram=y)

      0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices

      0x04   ignore NVRAM "Wide negotiation"  parameter for all devices

      0x08   ignore NVRAM "Scan at boot time" parameter for all devices

My Atlas Wide only boots cleanly in 8 bits asynchronous data transfer

mode. However, it works flawlessly at 20 MB/second with the driver.

Using "nvram=0x7" allows me to boot in 8 bits/async and to let the driver

use its setup for synchronous and wide negotiations.

10.6 SCSI BUS checking boot option.

When this option is set to a non-zero value, the driver checks SCSI lines

logic state, 100 micro-seconds after having asserted the SCSI RESET line.

The driver just reads SCSI lines and checks all lines read FALSE except RESET.

Since SCSI devices shall release the BUS at most 800 nano-seconds after SCSI

RESET has been asserted, any signal to TRUE may indicate a SCSI BUS problem.

Unfortunately, the following common SCSI BUS problems are not detected:

- Only 1 terminator installed.

- Misplaced terminators.

- Bad quality terminators.

On the other hand, either bad cabling, broken devices, not conformant

devices, ... may cause a SCSI signal to be wrong when te driver reads it.

11. Some constants and flags of the ncr53c8xx.h header file

Some of these are defined from the configuration parameters.  To

change other "defines", you must edit the header file.  Do that only

if you know what you are doing.

SCSI_NCR_SETUP_SPECIAL_FEATURES (default: defined)

        If defined, the driver will enable some special features according

        to chip and revision id.

        For 810A, 860, 825A, 875 and 895 scsi chips, this option enables

        support of features that reduce load of PCI bus and memory accesses

        during  scsi transfer processing: burst op-code fetch, read multiple,

        read line, prefetch, cache line, write and invalidate,

        burst 128 (875 only), large dma fifo (875 only), offset 16 (875 only).

        Can be changed by the following boot setup command:

                ncr53c8xx=specf:n

SCSI_NCR_IOMAPPED               (default: not defined)

        If defined, normal I/O is forced.

SCSI_NCR_SHARE_IRQ              (default: defined)

        If defined, request shared IRQ.

SCSI_NCR_MAX_TAGS               (default: 8)

        Maximum number of simultaneous tagged commands to a device.

        Can be changed by "settags  "

SCSI_NCR_SETUP_DEFAULT_SYNC     (default: 50)

        Transfer period factor the driver will use at boot time for synchronous

        negotiation. 0 means asynchronous.

        Can be changed by "setsync  "

SCSI_NCR_SETUP_DEFAULT_TAGS     (default: 8)

        Default number of simultaneous tagged commands to a device.

        < 1 means tagged command queuing disabled at start-up.

SCSI_NCR_ALWAYS_SIMPLE_TAG      (default: defined)

        Use SIMPLE TAG for read and write commands.

        Can be changed by "setorder "

SCSI_NCR_SETUP_DISCONNECTION    (default: defined)

        If defined, targets are allowed to disconnect.

SCSI_NCR_SETUP_FORCE_SYNC_NEGO  (default: not defined)

        If defined, synchronous negotiation is tried for all SCSI-2 devices.

        Can be changed by "setsync  "

SCSI_NCR_SETUP_MASTER_PARITY    (default: defined)

        If defined, master parity checking is enabled.

SCSI_NCR_SETUP_MASTER_PARITY    (default: defined)

        If defined, SCSI parity checking is enabled.

SCSI_NCR_PROFILE_SUPPORT        (default: not defined)

        If defined, profiling information is gathered.

SCSI_NCR_MAX_SCATTER            (default: 128)

        Scatter list size of the driver ccb.

SCSI_NCR_MAX_TARGET             (default: 16)

        Max number of targets per host.

SCSI_NCR_MAX_HOST               (default: 2)

        Max number of host controllers.

SCSI_NCR_SETTLE_TIME            (default: 2)

        Number of seconds the driver will wait after reset.

SCSI_NCR_TIMEOUT_ALERT          (default: 3)

        If a pending command will time out after this amount of seconds,

        an ordered tag is used for the next command.

        Avoids timeouts for unordered tagged commands.

SCSI_NCR_CAN_QUEUE              (default: 7*SCSI_NCR_MAX_TAGS)

        Max number of commands that can be queued to a host.

SCSI_NCR_CMD_PER_LUN            (default: SCSI_NCR_MAX_TAGS)

        Max number of commands queued to a host for a device.