
    $Id: readme.first 1.18 1997/10/13 18:27:08 heinz Exp $

NSDPatch
========

What is NSDPatch?
-----------------

NSDPatch will hook into the OS (V37+, 2.04+) and patch almost
arbitrary types of Exec devices to make them look like NSD compliant
devices. With a configuration file, you can set up NSD like
behaviour even for most devices that were not known to the authors
of NSDPatch. NSDPatch does not affect DOS devices like PAR: in
any way. NSDPatch only handles Exec devices.

NSDPatch also includes some support for trackdisk like devices to
emulate the NSD 64 bit access commands on top of old devices. With
NSDPatch and the AI V43 FFS, you can use partitions >4GB on disks
>4GB.

NSDPatch also includes RDB mount functionality to support special
configurations.

NSDPatch also fixes some bugs with certain devices like the V40
mfm.device or incompatibilities of, e.g., a JAZ drive and V40
scsi.device.

NSDPatch will allow you to turn on correct command rejection via
IOERR_NOCMD for devices that would crash otherwise.

NSDPatch will optionally try to do some magic for broken SANA2
devices, too.

NSDPatch may also be useful for developers of NSD using SW to
simulate different and possibly incomplete or buggy NSD
environments for testing.

NSDPatch makes it possible to install device/unit mappings to
virtually rename device units to support broken software that
test only the device name for assumed functionality.

NSDPatch is not intended to replace an NSD upgrade for old devices
forever. It is also not intended to provide for every single NSD
bell and whistle in the specs. It is intended to ease the migration
path and to give some basic NSD capabilities and convenient fixes
to those who otherwise couldn't have it at all.


What is NSD?
------------

NSD is referring to the New Style Device standard as documented on
the Amiga Technologies Amiga Developer CD in the

    Amiga_Dev_CD_v1.1:DevInfo/DeviceDevelopment

directory. It is intended to provide for clean device usage in the
future.

Updates to this standard are available on ftp.amiga.de and it is
probably a good idea to check for them once in a while.

If you want more information about NSD, you can also contact the
author of this document at the address mentioned below.


WARRANTY AND LEGALES
--------------------

WARRANTY: None whatsoever. Standard disclaimer applies.

LEGALESE: FREELY REDISTRIBUTABLE, NOT PD! CHANGES NOT ALLOWED!


Installation
------------

****************
*** READ IT! ***
****************

There is an Installer-Script "Install" included, that does a quick
installation and setup of NSDPatch, including its configuration.
If you go this way, you may still want to read below about what
happens. If you don't want the automatic installation, you can read
below about the details of a custom installation.

First, take a look at the demonstration configuration file
NSDPatch.cfg. It describes in detail all the available
configuration options and contains all the entries for a basic OS
3.1 based system including entries for devices known to be broken.
When you have looked it over and want to boldly go where quite a
few now have gone before, proceed like this:

  A. BASIC INSTALLATION

    1. Make a copy of the file NSDPatch.cfg, and and place it
       preferrably into SYS:DEVS, with SYS: referring to your boot
       volume.

    2. Copy NSDPatch into SYS:C.

    3. Check the configuration file in SYS:DEVS for any devices
       that you don't want to have patched and comment out these
       lines. Add entries for any special devices. Please report
       configuration lines for 3rd party devices to the author.
       Keep another copy of your changes in case of future
       automatic updates. Use NSDQuery to check if a device already
       supports NSD.

    4. Place a line like this into your SYS:S/Startup-Sequence
       immediately after SetPatch is called:

        NSDPatch

       It is very important that this line is added immediately
       after SetPatch. That is why NSDPatch must be placed into
       SYS:S/Startup-Sequence and not in User-Startup.

       Alternatively, you can run the included Installer-Script
       "Install", which does a quick installation of NSDPatch.

       SPECIAL NOTE: If you map trackdisk.device units, you must
       start any "noclick" hack _after_ SetPatch but _before_
       NSDPatch.

    5. Reboot and watch the messages that are output by NSDPatch.
       These messages tell you what NSDPatch does. If you can't
       agree with them in some way, go back to 3.

    6. Try NSDQuery on patched devices to check if everything was
       successful. If you encounter problems that can't be fixed
       by going back to 3., check B and C below.
       Please report all problems to the author with the device
       names and versions that cause the problems!

    7. Assuming there were no problems, add the "QUIET" option to
       the NSDPatch line in your startup.

    8. That's it. This is the end of a successful installation.


  B. SPECIAL INSTALLATIONS

    1. You may have 3rd party devices which don't support
       IOERR_NOCMD correctly. This means that the driver will not
       reject unknown commands with IOERR_NOCMD, but either crash
       or do very strange things instead. In that case, use the
       IOERRNOCMD option for the respective patch configuration
       line. If you want to boot from such a device, read the
       description of the RDBUNIT option carefully. If you
       encounter such a device, please report it to the author.

    2. You may have a trackdisk like device supporting the 3rd
       party TD64 command set. In that case, use the TD64 option
       for the respective patch configuration. By using the
       TD64 option, the official NSD 64 bit commands will be
       rerouted to the already existing TD64 functionality instead
       of being emulated via HD_SCSICMD. Current Guru-ROM's and
       Phase 5 SCSI devices may support TD64. No exact versions can
       be named at this time.

    3. NSDPatch can be invoked multiple times to install more
       patches. Installed patches cannot be changed without a
       reboot.

    4. You can invoke NSDPatch with a config file that doesn't
       actually patch anything but only uses the ACTIVATE and
       RDBUNIT features of NSDPatch. This is considered a positive
       side effect of the NSDPatch design.

    5. You may have a SANA2 device that can't handle a NULL
       ios2_BufferManagement pointer on startup. If you have one of
       those, you'll get enforcer hits with most likely an access
       to address 0 first on a check with NSDQuery. In that case,
       specify the SANA2MAGIC option in the configuration.


  C. TROUBLE SHOOTING

    1. In the unlikely case that NSDPatch crashes your machine on
       the first invocation, you may want to

        - try NSDPatch with an empty configuration file to verify
          basic installation compatibility.

        - reduce the configuration file to a single line, e.g. for
          parallel.device to make testing easier.

        - check your system for any virus

    2. If you are not sure if a patch was successful, use the
       NSDQuery tool to check on that device.

    3. If multiple calls to NSDQuery while a device is in memory
       reveal that the reported io_Device value changes for every
       invocation, NSDPatch will not be able to patch this device
       for any openers that opened the device before NSDPatch was
       installed. This is not a bug in NSDPatch.

    4. If NSDQuery behaves strangely on any device, patched or not,
       please report the exact circumstances, including all
       configuration and version information for your Amiga.

    5. The NSDPatch 64 bit disk emulation capabilities or the
       FIXSCSIUPDATE option may not work as expected on an IDE
       scsi.device that has been patched by atapi.device. This is
       not a bug in NSDPatch.

  D. ADDING NEW PATCH LINES

    1. The safe solution is emailing a copy of the device in
       question to the author. He will generate a suitable patch
       line to be placed into NSDPatch.cfg. The quick and dirty
       solution is outlined below.

    2. First make sure that everything important is saved because
       the tests for what you need may crash the system. If
       possible, run Enforcer.

    3. Try NSDQuery on the device. If your Amiga crashes or severly
       misbehaves, you will need the IOERRNOCMD option! If you get
       a report that the device is NSD, you don't need to patch it.

    4. Check NSDPatch.cfg for an existing similar line and make
       a copy, changing the name appropriately. If you have, e.g.,
       magicscsi.device, you may want to use the line
       for scsi.device as first approximation and put the name
       magicscsi.device into the copied line. For, e.g.,
       mynewaudio.device, you would take the line for audio.device
       as example.

    5. Put the new line with the device's name into NSDPatch.cfg.
       If needed according to 3., add the IOERRNOCMD option if it
       isn't already there.

    6. Start NSDPatch and try NSDQuery again. Now, the device
       should respond as NSD device, based on the new config line.

    7. Never change too many patch options at once. After changing
       a patch option, you must reboot for it to take effect.
       Read the descriptions in NSDPatch.cfg before using options.

    8. In case of any more problems, contact the author.

    9. If the patch line works well and solves your problems,
       please forward it to the  author.

Contact
-------

If you have any comments on NSDPatch, please send them to:

    Heinz Wrobel
    Karlstr.16
    82131 Gauting
    Germany
    <heinz@hwg.muc.de>


Implementation
--------------

This may not be very interesting to most readers as it hints at
some technical details. NSDPatch hooks itself into the exec.library
OpenDevice() function. It will patch any opened device that should
be patched and "preprocess" requests sent to it this way. The user
software sees an NSD device then and the device itself will not
have to be reworked in strange device specific ways. Devices
patched like this can still be expunged and reloaded freely. The
permanent NSDPatch footprint in memory is about 4KB plus memory for
configuration data for each device to be patched. NSDPatch does not
need to be started in the background and it does not use any ugly
SegList splitting hacks or similar stunts. NSDPatch should also be
compatible to all debugging tools.


History
-------
43.15
    - The version/revision match code ignored general patch
      requests. This made it impossible to patch, e.g., an ISNSD
      device with FIXSCSIUPDATE.

43.14
    - Cleanup for FIXSCSIUPDATE option. Will ignore an error on
      internal handling now just like scsi.device. This keeps
      FORMAT happy.

43.13
    - Cleaned up some of the 64 bit emulation code. A few SCSI
      CDB's are set up better now. Added FIXSCSIUPDATE option. It
      will turn CMD_UPDATE for scsi.device into something that does
      no longer conflict with JAZ drive behaviour even though it
      should still work as expected for other devices. NSDPatch
      will use significantly less stack in its BeginIO patch for
      patched devices in the general case now.

43.12
    - NSDPatch no longer pops up requesters when activating DOS
      devices. Whenever you specify QUIET as option, NSDPatch will
      no longer complain about already mounted entries when using
      the RDB functionality. More updates to the config file.
      SINLEPATCHONLY is now the default option as it tends to be
      a lot more compatible to many debug tools commonly used with
      AmigaOS. To get the the old behaviour back where the device
      specific patch is reinstalled for each and every OpenDevice,
      you can use the new TRYMULTIPATCH option. Note that with
      other tools patching into the same vectors you may cause
      infinite loops when using this option!

43.11
    - Added MOUNTANY option for RDB support. This facilitates RDB
      mount magic by allowing access to any partition, not just
      partitions not marked as automount. It is meant for the
      advanced user. Added PATCHCONFIGLINE command line option. You
      can use NSDPatch with a single simple config line. It will
      not read in a config file then unless you also specify one.
      The default DEVS:NSDPatch.cfg will now only be read if no
      command line options have been used. Updated the
      configuration file a little.

43.10
    - Added SINGLEPATCHONLY option for device patch lines. With this
      option, a device will only patched for its initial open call.
      This fixes interaction with CMD, which will hang in an endless
      loop without SINGLEPATCHONLY. This again shows how dangerous
      the use of the exec.library SetFunction() call is.

43.9
    - Should work with >=V37 now.
    - Supports device mapping now. Implementation of this feature
      has been funded by ATL, Inc.

43.8
    - Reduced stack usage during OpenDevice() patch by about 32
      bytes. The patch needs about 68 bytes now during OpenDevice().
    - The SANA2MAGIC did not work very well. There was a problem in
      handling paths. So it often did not even get activated.

43.7
    - There was a bug in the Version/Revision recognition.
      NSDPatch patched too much at times. This should not have
      hurt, though.
    - Reduced processing time in OpenDevice() a little.
    - Mixing different versions of NSDPatch should not cause any
      harm now.
    - Added new PatchInfo option that tells you about NSDPatch
      activities. Note: This option is more of a debugging hack!
    - More patch lines.

43.6
    - Now supports LVO's that can't normally be SetFunction()'ed.
    - Now supports version specific patches correctly. The override
      general patches.
    - Now supports special SANA2MAGIC for callback handling of old
      devices.
    - Now checks the default patch file DEVS:NSDPatch.cfg
      automatically, if none has been specified.
    - The config file is no longer named v40.nsdpatchcfg. It now
      already has the default name and also has a C= version
      string.

Acknowledgements
----------------

Some were very directly involved in thinking up and testing
NSDPatch. Here is a list in no particular order:

    Olaf Barthel
    Bernhard Möllemann
    Michael van Elst
    Angela Schmidt
    Klaus Burkert
    Joanne Dow

Thank you.

Heinz Wrobel
