The greater of (tune_t_minarmem + 100 and [4% of memory available at boot time + 4 MB])
Minimum value enforced by the system is tune_t_minarmem + 100. The system does not enforce a maximum value.
Yes, unless dynamic reconfiguration operations that add or delete memory occur. At that point, the value is reset to the value provided in the /etc/system file or was calculated from the new physical memory value.
If the value specified in the /etc/system file or the calculated default is less than tune_t_minarmem + 100, the value is reset to tune_t_minarmem + 100.
No message is displayed if the value from the /etc/system file is increased. Validation is done only at boot time and during dynamic reconfiguration operations that involve adding or deleting memory.
When memory-locking requests fail or when attaching to a shared memory segment with the SHARE_MMU flag fails, yet the amount of memory available seems to be sufficient.