Dear SCO Customer,

The enclosed Support Level Supplement (SLS) UOD399A corrects problems 
found in kernel modules in these products:

	  SCO UNIX System V/386 Release 3.2 Operating System Version 4.2
	  SCO Open Server Enterprise System Release 3.0
	  SCO Open Server Network System Release 3.0
	  SCO Open Desktop Release 3.0
	  SCO Open Desktop Lite Release 3.0

The kernel module problems corrected by SLS UOD399A are:

   - A synchronous write to a file when the file system is full 
     hangs the operating system.

   - A possible system hang when performing raw transfers 
     above 16 MB of physical memory.

Performance enhancements: 

   - Modifications have been made to kernel modules to improve 
     performance when SCO NFS is being used.



Using custom(ADM) to Install or Remove SLS UOD399A

A. Installing SLS UOD399A

1.  If the system is running in multiuser mode, log in as root on 
    the console.  After warning the users that the system will be 
    down for some time, enter the command:

        shutdown  -y -g0 

    The system will then execute a controlled shutdown operation 
    which displays this message when the shutdown process is  
    complete: 

        **   Safe to Power Off   **
                   -or-
        ** Press Any Key to Reboot **

2.  Reboot the system.

3.  When the system reboots, you will see the message:

        Type CONTROL-d to proceed with normal startup,
        (or give root password for System Maintenance):

    Enter the root password and press <Enter>.
    Wait until the "#" prompt appears.

4.  Insert the custom volume diskette labeled "SCO OS I/O Supplement
    1.0 UOD399" in the floppy drive and enter the command:

        /etc/custom

    The custom menu will appear.

5.  To select the following, highlight each one with the cursor keys
    and press <Enter>:

        Install -> A New Product -> Entire Product


   - Position the cursor so that "Install" is highlighted and 
     press <Enter>.

   - Make sure the words "A New Product" are highlighted in the window
     found in the lower right corner of the screen; press <Enter>.

   - Make sure the words "Entire Product" are highlighted in the 
     "Choose an option" section of the screen; press <Enter>.

   - You will be prompted to "Insert: Distribution Floppy Volume 1 
     and press <Enter>".  The diskette is already in the drive, 
     therefore press <Enter>.

   - You will see the following messages:

       Installing custom data files ...
       Executing Product Prep Script
   
   - You will be prompted to "Insert the requested Volume and 
     press <Enter>".  The diskette is already in the drive, 
     therefore press <Enter>.

   - You will see the message:

       Extracting Files

   - When asked if you wish to relink the kernel, reply "y" in order 
     to ensure that the modifications from SLS UOD399A are included 
     in the kernel.

     Answer "y" when asked if you want to boot off this kernel.

     Answer "y" when asked if you want to rebuild the kernel 
     environment.

   - You will then be prompted to "Press any key to continue"; 
     press <Enter>.

   - At the main custom menu, move the highlighted entry to "Quit" 
     and press <Enter>.  Press <Enter> again on the highlighted "yes".
     
   - Remove the diskette and reboot the computer.

   - SLS UOD399A is now successfully installed.


B. Removing SLS UOD399A

1.  If the system is running in multiuser mode, log in as root on 
    the console.  After warning the users that the system will be 
    down for some time, enter the command:

        shutdown  -y -g0 

    The system will then execute a controlled shutdown operation 
    which displays this message when the shutdown process has
    completed:

        **   Safe to Power Off   **
                   -or-
        ** Press Any Key to Reboot **

2.  Reboot the system.

3.  When the system reboots, you will see the message:

        Type CONTROL-d to proceed with normal startup,
        (or give root password for System Maintenance):

    Enter the root password and press <Enter>.
    Wait until the "#" prompt appears.

4.  Use the custom utility to remove this SLS.  At the command line,
    enter the command:

        /etc/custom

    The custom menu will appear.

5.  To select the following, highlight each one with the cursor keys 
    and press <Enter>:

        Remove -> SCO OS I/O Supplement 1.0 UOD399 -> ALL

   - Position the cursor so that "Remove" is highlighted and 
     press <Enter>.

   - Make sure to move the highlighted cursor to: "SCO OS 
     I/O Supplement 1.0 UOD399" to select this package; press 
     <Enter>.

   - Make sure the word "ALL" is highlighted as the selected package to
     remove; press <Enter>.

   - Make sure the word "ALL" is highlighted under "Please verify the 
     removal of the following packages"; press <Enter>.

   - When asked if you wish to relink the kernel, reply "y" in order 
     to ensure that the modifications from SLS UOD399A are removed 
     from the kernel.

     Answer "y" when asked if you want to boot off this kernel.

     Answer "y" when asked if you want to rebuild the kernel 
     environment.

   - You will then be prompted to "Press any key to continue"; 
     press <Enter>.

   - At the main custom menu, move the highlighted entry to "Quit" 
     and press <Enter>.  Press <Enter> again on the highlighted "yes".
     
   - Reboot the computer.

   - SLS UOD399A has now been successfully removed.


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