The following Shared Memory and Semaphore kernel tunable 
          parameters do not appear to be documented:

                SEMMAP
                SEMMNI
                SEMMNU
                SEMMSL
                SEMOPM
                SEMUME
                SEMMNS
                SHMMAX
                SHMMNI
                
          What are their maximum values?

          Maximum values for the above as follows:

            SEMMAP  - No maximum as such, other than the signed integer 
                      limit (2GB). However, the size of the data structure 
                      it controls is limited by the maximum size of the 
                      kernel (8MB), and will therefore be affected by how 
                      the kernel is configured in terms of other tunable 
                      parameters and drivers.

                      When the 8MB limit has been exceeded the kernel link 
                      will fail with the following error: 

                          can't allocate section .bss

            SEMMNI  - Same as SEMMAP
            SEMMNU  - Same as SEMMAP
            SEMMSL  - Same as SEMMAP
            SEMOPM  - Same as SEMMAP
            SEMUME  - Same as SEMMAP
            SEMMNS  - Same as SEMMAP

            SHMMAX  - Again, no maximum, other than signed integer limit. 
                      This is used by the shared memory subsystem only 
                      as a check, and does not control the size of a 
                      data structure.

                      The real limitations for a process using shared 
                      memory are:

                         1. Total available virtual memory (user space + swap
                            space).

                         2. Shared memory's position in the system's virtual
                            address space.

                      In order to avoid 2 (when using shared memory whose
                      address is assigned by the kernel), set SHMMAX to
                      256MB.

            SHMMNI  - Same as SEMMAP