Dear SCO Customer,

The enclosed Support Level Supplement (SLS) PTF3087, the Enhanced 'procfs'
Driver, corrects the threaded telephony application hang.
 
An application creating several threads using thr_create(), both with 
and without THR_BOUND being set in the flags argument, occasionally hangs. 

Under unpredictable circumstances, a thread that is creating another LWP 
will be suspended between its call to the _lwp_create() system call and 
its call to _lwp_continue(). This can be seen most clearly when all threads 
are created as bound threads, since in that case _lwp_ create() is being 
called directly from thr_create(). However, the problem still occurs even 
if THR_BOUND is not specified -- it just gets deferred until the next time 
the thread library needs to call _lwp_create().  When this problem occurs,
a "ps" shows both the parent thread and the child thread in the T (suspended)
state.


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


PTF3087 should only be installed on these releases:

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


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

1. Become root and create a new directory by typing the following:
 
     $ su
     Password: <type your root password>
     # mkdir /tmp/pkg
     # chmod 700 /tmp/pkg
     # cd /tmp/pkg

2. Download the ptf3087.Z and the ptf3087.txt files to the newly
   created /tmp/pkg directory on your machine.
 
3. Read the Release Notes contained in the ptf3087.txt file.
 
4. Uncompress the file and add the package to your system using these
   commands:
 
     # uncompress /tmp/pkg/ptf3087.Z
     # pkgadd -d /tmp/pkg/ptf3087 


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

1. Become root and remove the package by typing these commands:

     $ su
     Password: <type your root password>
     # pkgrm ptf3087


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