Dear SCO Customer,

Support Level Supplement (SLS) ptf4012b, the CDFS Concurrency Supplement,
provides various fixes to the CD-ROM FileSystem Driver provided with SCO
UnixWare Operating Systems Releases 2.1.1, 2.1.2, and 2.1.3.

SLS ptf4012b contains modified versions of the following files:

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

Load tests of the CD-ROM on a MultiProcessing (MP) system, in which the CD-ROM
is attached to a MultiProcessing Host Board Adapter (HBA), have demonstrated
panics. This problem is not addressed by ptf4012b, but instead is corrected
by SLS ptf4013b, the SDI Driver Supplement. It is recommended that both SLSs
be installed for a more complete solution to identified CD-ROM driver issues.


Problem Specifics
-----------------

Several problems in the CD-ROM FileSystem Driver were found and addressed in
SLS ptf4012b:

   1.   Concurrent "ls -lRs" of the CD-ROM generated many spurious ENOENT
        "No such file or directory" errors, even on a UniProcessor system.
        Directory offsets for different processes were interfering with
        each other.

   2.   Concurrent "ls -lRs" of the CD-ROM generated many spurious ENFILE
        "File table overflow" errors, running on a MultiProcessor system
        (as well as "WARNING: cdfs_GetInode: inode table overflow" messages).
        When multiple processors competed for a free inode, the backoff
        mechanism allowed for only a single clash.

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

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

   5.   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 were found.  Although rare, these
        problems could cause data corruption, systems panics, or freezes.

   6.   RRIP_SLCR_HOST and RRIP_NM_HOST flags would use "UNIX_SV" instead of
        the host's nodename.


SLS ptf4012b supersedes ptf4012a which did not address issues 4 and 5 listed
above.


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

SLS ptf4012b should only be installed on:

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

SLS ptf4012b contains changes to the following packages in UnixWare 2.1.x:

        - Base System                  (base)
        - OS Multiprocessor Support    (osmp)

If you are preparing to install any of these modified packages, discontinue
the installation of ptf4012b, install those packages first, and then install
ptf4012b.

Note which of the above packages are affected by SLS ptf4012b.  If you
later install any of these packages on your system, you must reinstall this
SLS to get the fixes for those packages.

Note that SCO UnixWare 2.1.1 is no longer supported or warranted by SCO.
SCO strongly recommends that you upgrade to SCO UnixWare 2.1.3 by applying
update213.

SLS ptf4012b supersedes SLS ptf4012a; however, it is not necessary to
remove ptf4012a prior to installing ptf4012b.


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

1. Download the ptf4012b.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
        # uncompress /tmp/ptf4012b.Z
        # pkgadd -d /tmp/ptf4012b

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

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

        /var/sadm/pkg/ptf4012/install/ptf4012.txt


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

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

        # pkgrm ptf4012

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


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