Dear SCO Customer,

Support Level Supplement (SLS) PTF4013B, the SDI Driver Supplement,
provides various fixes to the SDI Driver included with SCO UnixWare
Operating Systems Releases 2.1.0, 2.1.1, 2.1.2, and 2.1.3.


SLS PTF4013B corrects these problems:

Load testing of the CD-ROM driver (sc01) on a multiprocessor system
can sometimes panic the system.  This occurs because the sc01 driver
is a single-threaded, uniprocessing target and during load testing,
sdi_callback() may perform the target's interrupt callback on a
different processor from that to which it was bound, which will
violate its concurrency assumptions.

The same problem could apply to other single-threaded SCSI targets
including mc01 (medium changer), sp01 (processor), st01 (tape), sw01
(worm), cled (Compaq ProLiant processor); PTF4013B addresses these
issues.

One additional issue is addressed by SLS PTF4013B as opposed to SLS
PTF4013A: under certain specific conditions, a panic could occur in
the SDI driver on system startup.  This panic would occur in the
function sdi_register().


Contents
--------

The following files are updated:

        /etc/conf/pack.d/sdi/Driver_atup.o
        /etc/conf/pack.d/sdi/Driver_mp.o


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

SLS PTF4013B should only be installed on: 

        SCO UnixWare Application Server Release 2.1.0, 2.1.1, 2.1.2, 2.1.3
        SCO UnixWare Personal Edition Release 2.1.0, 2.1.1, 2.1.2, 2.1.3

SLS PTF4013B supersedes SLS PTF4013A.

Load tests of the CD-ROM also showed spurious ENOENT and ENFILE errors
generated by the the CDFS driver.  These problems are not addressed by
PTF4013B, but instead are corrected in PTF4012A, the CDFS Concurrency
Supplement.  It is recommended that both SLSs be installed for a more
complete solution to identified CD-ROM driver issues.

The following UnixWare 2.1.x packages are modified:

        Base System                  (base)
        OS Multiprocessor Support    (osmp)

If you are preparing to install any of these modified packages,
discontinue the installation of PTF4013B, install those packages
first, and then install PTF4013B.

Note which of the above packages are affected by SLS PTF4013B.  If you
later install any of these packages on your system, you must reinstall
this SLS to obtain the fixes for those packages.


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

1. Download the ptf4013b.Z file to the /tmp directory on your
   machine.

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

        $ su
        Password: <type your root password>
        # uncompress /tmp/ptf4013b.Z
        # pkgadd -d /tmp/ptf4013b
        # rm /tmp/ptf4013b

3. Shut down and reboot the system after installing this package.

The release notes displayed prior to installation can be found in

/var/sadm/pkg/ptf4013/install/ptf4013.txt


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

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

        $ su
        Password: <type your root password>
        # pkgrm ptf4013

2. Shut down and reboot the system after removing this package.


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