System V IPC CONFIG_SYSVIPC Inter Process Communication is a suite of library functions and system calls which let processes (running programs) synchronize and exchange information. It is generally considered to be a good thing, and some programs won't run unless you say Y here. In particular, if you want to run the DOS emulator dosemu under Linux (read the DOSEMU-HOWTO, available from http://www.linuxdoc.org/docs.html#howto ), you'll need to say Y here. You can find documentation about IPC with "info ipc" and also in section 6.4 of the Linux Programmer's Guide, available from http://www.linuxdoc.org/docs.html#guide . Shared memory is now implemented using a new (minimal) virtual file system, which you need to mount before programs can use shared memory. To do this automatically at system startup just add the following line to your /etc/fstab: none /var/shm shm defaults 0 0 Saying Y here enlarges your kernel by about 18 KB. Just say Y.