Dear SCO Customer,

Support Level Supplement (SLS) PTF7035A, the CDFS Concurrency Supplement,
addresses a variety of problems found in the CD-ROM filesystem driver. 

SLS PTF7035A can be installed on UnixWare 7.0.0, 7.0.1, and 7.1.0.  Most
fixes included in this SLS already exist in UnixWare 7.1.0 with the exception 
of problem number four listed below.


SLS PTF7035A corrects these problems:
-------------------------------------

   1.   Concurrent "ls -lR"s of the CD-ROM generated many spurious ENOENT
        errors "No such file or directory", even on a single-processor
        system.  Directory offsets for different processes were interfering 
        with each other.
        
   2.   When running on a multiprocessor system, concurrent "ls -lR"s of the 
        CD-ROM generated many spurious ENFILE errors of "File table overflow". 
        Also, "WARNING: cdfs_GetInode: inode table overflow" messages occur.
        When multiple processors competed for a free inode, the backoff
        mechanism allowed for only a single clash.

   3.   The ENFILE problem noted above could degenerate to the point where 
        almost all attempts to locate a CDFS file would fail with a "File 
        table overflow" error, and the CD-ROM could not be accessed at all 
        until it was unmounted and remounted.  When a certain kind of clash 
        occurred, a free inode was left locked.

   4.   A single "ls -lR" of the CD-ROM, even on a single-processor system,
        could occasionally generate a spurious ENFILE error and WARNING as
        above.  The way in which CDFS freed its entries from the Directory
        Name Lookup Cache was inadequate.

   5.   Rarer problems that might cause data corruption, panic, or freeze
        were also fixed.  These were problems with the freeing and acquisition
        of freed CDFS inode table entries, problems in attempting to unmount
        a busy CDFS filesystem, and problems with CDFS page I/O locking.


SLS PTF7035A contains these files:
----------------------------------

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


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

SLS PTF7035A should only be installed on:

        UnixWare 7.0.0, 7.0.1, 7.1.0

If the base or osmp package is installed or updated after PTF7035A has been
installed, PTF7035A must be reinstalled.

Load tests of the CD-ROM on a multiprocessing system, in which the CD-ROM 
is attached to a MultiProcessing Host Board Adapter, showed panics prior to
UnixWare 7.1.0.  PTF7035A does not fix that issue.  It is independently 
fixed in the SDI driver provided for UnixWare 7.0.0 by PTF7002 (version 'g' 
or later) or, for UnixWare 7.0.1, by PTF7036 or update710.


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

1. Download the ptf7035a.Z ptf7035a.txt files 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/ptf7035a.Z
        # pkgadd -d /tmp/ptf7035a
        # rm /tmp/ptf7035a

3. Reboot the system after installing this package.

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

        /var/sadm/pkg/ptf7035/install/ptf7035.txt


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

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

        $ su
        Password: <type your root password>
        # pkgrm ptf7035

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.