100 \s+2Interim Report on Operating Systems Research in the Berkeley UNIX Project\s-2 October 1, 1989 - December 31, 1989 Susan L. Graham Domenico Ferrari Marshall Kirk McKusick Michael J. Karels Keith Sklower

0 .pp Berkeley continues to participate in the Posix Standardization effort. .pp We completed an implementation of Connectionless mode Transport, did some rudimentary testing, and collaborated with Marshall Rose in modifying the SNMP agent to make use of it. .pp We are continuing our development of X.25 support for CLNP and CONS. These changes are being made so that it can gracefully co-exist with IP over public data networks and the DDN. It should work over a variety of drivers (including front-end processors), and with the possibility of multiple X.25 interface boards on a given machine. This work requires some changes to the network routing layer. .pp We have fixed many bugs and performance problems during this period. We found and corrected a bug in our ``fix'' to avoid silly window syndrome between the socket layer and transport. We have found and fixed bugs specific to the microvax version that kept the message passing routing mechanism from working, and issuing explicit connection confirmation requests. .pp We are pursing problems, yet to be resolved, with ESIS ISH's and redirects. We are also tracking down the mishandling of a kernel resource exhaustion bug that was exposed by the most recent version of ISODE. .pp We are collaborating with colleagues at NIST to determine why the Wisconsin/BSD transport refuses SUNLINK connection requests, but can establish connections in the other direction. One such problems (recently corrected) involved a protocol violation of increasing a negotiated parameter during connection setup (packet size on a local ethernet). .pp We have received and are incorporating changes from MITRE about reception of the congestion-experienced bit. .pp A pageable memory based file system was implemented under the vnode interface. It is typically used for the /tmp file system where fast access is more important than longevity of file data. .pp The semantics of POSIX sessions were completed with the addition of code to implement revocation of the controlling terminal when the session leader exits. These semantics are implemented with a fourth file system type that rejects all attempts for access.