Dear SCO Customer, Support Level Supplement (SLS) PTF4008 reinstates the pre-UW213 behavior of poll(2) on named pipes (FIFO) when no process has the FIFO open for writing. SLS PTF4008 replaces the following files: /etc/conf/pack.d/fifofs/Driver_atup.o /etc/conf/pack.d/fifofs/Driver_mp.o PLEASE NOTE: This change will not be carried forward into UnixWare 7. The behavior under consideration is as follows: 1) A named pipe is open for reading. 2) There is no process having the named pipe open for writing. 3) poll(2) using POLLIN or POLLRDNORM or select(2) is performed on the named pipe. The SCO UnixWare 2.1.2 (and earlier releases) behavior is that a call to poll(2) and select(2) will not return until a writer has opened the pipe and written data to it. The SCO UnixWare 2.1.3 (and UnixWare 7) behavior is that the call to poll(2) and select(2) will return immediately. In this case a read(2) on the named pipe will return zero bytes with no error. A workaround exists in that if the FIFO is opened for reading and writing (O_RDWR) rather than read-only (O_RDONLY), the behavior of the poll(2) call will be as per SCO UnixWare 2.1.2. The use of SIGPOLL signal notification when requested via the ioctl command I_SETSIG remains unchanged (see streamio(7) for further details). Software Notes and Recommendations ---------------------------------- This SLS should only be installed on: SCO UnixWare Application Server Release 2.1.3 SCO UnixWare Personal Edition Release 2.1.3 Installation Instructions ------------------------- 1. Download the ptf4008a.Z and ptf4008a.txt files to the /tmp directory on your machine. 2. As root, add the package to your system using these commands: $ su # uncompress /tmp/ptf4008a.Z # pkgadd -d /tmp/ptf4008a 3. You can safely ignore the message indicating that Update 2.1.3 should be reapplied as this is unnecessary. 4. Shut down and reboot the system after installing this package. Removal Instructions --------------------- 1. As root, remove the package using these commands: $ su # pkgrm ptf4008 2. Shut down and 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