Memory addition

Overview

After the system has booted, the standard kernel includes a block of physical memory for the kernels' memory allocator. Now, the memory addition feature lets you add more physical memory to the system after it's started.

Configuration

Use the _MEM_PMEM_ADD type and mem_pmem_add_t message structure to send a message to procnto to use the specified RAM for general allocation purposes.

For example, the following sample shows a partial illustartion of the memory addition feature:

int main(int argc, char *argv[]) {
  void *ptr;
  int fd, rc;
  uintptr_t rsvd_paddr;
  unsigned passed = 0;
  struct {
    mem_pmem_add_t pmem;
  } msg;
  iov_t useramram;
  msg.pmem.i.type = _MEM_PMEM_ADD;

...

  // attempt to reclaim the reserved memory
  rc = MsgSendnc(MEMMGR_COID, &msg, sizeof msg, NULL, 0);

...

Use the following startup options to reserve specific RAM from general use, and then pass in these same parameters into your _MEM_PMEM_ADD():

-r paddr, size, <0|1>

Verifying the physical address

To verify the physical address that was added by using the function mem_offset64(), you can request that physically contiguous memory be allocated by using either the MAP_PHYS, MAP_ANON, or MAP_PRIVATE flag; however, we recommend that you use the MAP_PHY flag.