Dear SCO Customer,

Support Level Supplement (SLS) ptf4042b, the SCO UnixWare 2.1.3 st01
Tape Driver Supplement, addresses all of the issues listed below.

SLS ptf4042a addressed these issues:

1. Reading a file mark does not position the tape after the file mark.

2. Tape commands do not time out even on a controller that supports
   timeouts.

3. It is possible for the tape driver to get into a state where it
   cannot be opened.

4. The system panics while reading DAT tapes in variable block mode.


SLS ptf4042b additionally addresses these issues:

5. With ptf4042a installed and using dd or cpio, if a tape is opened 
   in non-rewind mode, a block of data is read and the tape is closed, 
   skipping to the EOT side of the next file mark.

6. When some HBA Drivers, like Mylex or Qlogic, try to allocate
   contiguous 16 - 64MB of memory, a system hang or panic can occur, 
   as the st01 driver cannot handle such a large DMA list. The st01 
   driver has been modified to limit the maximum transfer length.
   With the Qlogic qlc1020 driver, an error message similar to this 
   may be displayed:

            PANIC: qlc1020: Job too big for DMA list


Contents
--------

        /etc/conf/pack.d/st01/Driver.o
        /etc/conf/pack.d/st01/space.c

Note that the file /etc/conf/pack.d/st01/space.c is not replaced,
but is changed using sed.


Software Notes and Recommendations
----------------------------------

SLS ptf4042b should only be installed on:

        SCO UnixWare Application Server Release 2.1.3
        SCO UnixWare Personal Edition Release 2.1.3

If your system is running any libraries or commands that are
contained in this SLS, then these programs will continue to run
with the old versions of these libraries or commands until the
the system is rebooted.

Note that when all necessary patches have been installed, it is
recommended that you reboot the system at the earliest opportunity.
This will ensure that no programs continue to run with the old
libraries or commands.


Installation Instructions
-------------------------

1. Download the ptf4042b.Z file to the /tmp directory on your machine.

2. As root, uncompress the file and add the SLS package to your system
   using these commands:

        $ su
        Password: <type your root password>
        # uncompress /tmp/ptf4042b.Z
        # pkgadd -d /tmp/ptf4042b
        # rm /tmp/ptf4042b

3. There is no need to reboot the system after installing this SLS
   package.

The release notes displayed prior to installation can be found in:

        /var/sadm/pkg/ptf4042/install/ptf4042.txt


Removal Instructions
--------------------

1. As root, remove the SLS package using these commands:

        $ su
        Password: <type your root password>
        # pkgrm ptf4042

2. There is no need to reboot the system after removing this SLS
   package.


If you have questions regarding this SLS, or the product on which
it is installed, please contact your software supplier.