os_msys_register() function
MSYS is a system level mbuf registry. Allows the system to share packet buffers amongst the various networking stacks that can be running simultaeneously. Mbuf pools are created in the system initialization code, and then when a mbuf is allocated out of msys, it will try and find the best fit based upon estimated mbuf size. os_msys_register() registers a mbuf pool with MSYS, and allows MSYS to allocate mbufs out of it.
Return value
0 on success, non-zero on failure