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Does FreeBSD support System V IPC primitives? Frequently Asked Questions for FreeBSD 2.X : Kernel Configuration : Does FreeBSD support System V IPC primitives?
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7.5. Does FreeBSD support System V IPC primitives?

Yes, FreeBSD supports System V-style IPC. This includes shared memory, messages and semaphores. You need to add the following lines to your kernel config to enable them.

            options    SYSVSHM
            options    "SHMMAXPGS=64"   # 256Kb of sharable memory
            options    SYSVSEM          # enable for semaphores
            options    SYSVMSG          # enable for messaging

Recompile and install.

NOTE: You may need to increase SHMMAXPGS to some ridiculous number like 4096 (16M!) if you want to run GIMP. 256Kb is plenty for X11R6 shared memory.

Frequently Asked Questions for FreeBSD 2.X : Kernel Configuration : Does FreeBSD support System V IPC primitives?
Previous: How do I enable support for QIC-40/80 drives?
Next: I have 128 MB of RAM but the system only uses 64 MB.