Behavior of shm_ctl()

The procnto microkernel for ARMv7 takes advantage of the ARMv7 MMU's physically-tagged cache to remove the 32 MB address space restriction imposed by the earlier ARM MMU architecture; the per-process address space is now 2 GB.

The microkernel doesn't implement the ARM-specific global memory region implemented by earlier microkernels for ARM. This means that shm_ctl() no longer has any ARM-specific special behavior:

• Objects created with shm_ctl() are always mapped into each process address space. These mappings are inherited across a fork() function.
• SHMCTL_GLOBAL is ignored, since all mappings are placed in the per-process address space.
• SHMCTL_PRIV and SHMCTL_LOWERPROT are ignored. All mappings are created in the per-process address space with user mode access protections.