Dear SCO Customer,

The enclosed Support Level Supplement (SLS) PTF3357, the Intel Pentium 
"Invalid Instruction" Erratum Supplement for SCO UnixWare, prevents the
invalid instruction problem from freezing the system.

On an Intel Pentium processor the instruction "CMPXCHG8B", when used with 
a LOCK prefix and a register destination operand (for example, F0 0F C7 C8), 
locks the processor until the system is reset.

The instruction CMPXCHG8B is illegal when used with a register destination 
operand, so that sequence would not normally be used.  However, a user may 
contrive for the processor to execute such an instruction sequence.  SLS 
PTF3357 prevents the processor lockup that formerly occurred.  The appropriate 
Illegal Instruction signal is delivered instead, and the system runs normally.


Contents
--------

        /etc/conf/mdevice.d/p5idt
        /etc/conf/pack.d/p5idt/Driver.o
        /etc/conf/sdevice.d/p5idt


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

PTF3357 should only be installed on these releases:

        SCO UnixWare Application Server Release 2.01, 2.02, 2.03
        SCO UnixWare Personal Edition Release 2.01, 2.02, 2.03
        SCO UnixWare Application Server Release 2.1.0, 2.1.1, 2.1.2
        SCO UnixWare Personal Edition Release 2.1.0, 2.1.1, 2.1.2


Hardware Notes and Recommendations
----------------------------------

This is not a problem on Intel i386 and Intel i486 processors (which do 
not support the CMPXCHG8B instruction), nor on Intel Pentium Pro and Intel 
Pentium II processors (which support the CMPXCHG8B instruction correctly).  
Nor has any such problem been reported on non-Intel processors.

SLS PTF3357 is only of benefit if your processor is a genuine Intel Pentium 
processor.  It has no effect if used on other processors.


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

1. Download the ptf3357.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/ptf3357.Z
        # pkgadd -d /tmp/ptf3357
        # rm /tmp/ptf3357

3. Reboot the system after installing this package.  The release 
   notes displayed prior to installation can be found in: 
   
        /var/sadm/pkg/ptf3357/install/ptf3357.txt


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

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

        $ su
        Password: <type your root password>
        # pkgrm ptf3357

2. 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.

We appreciate your business.

SCO Support Services