++ Using externally allocated memory without DPDK API's
+
+While using heap API's is the recommended method of using externally allocated
+memory in DPDK, there are certain use cases where the overhead of DPDK heap API
+is undesirable - for example, when manual memory management is performed on an
+externally allocated area. To support use cases where externally allocated
+memory will not be used as part of normal DPDK workflow, there is also another
+set of API's under the ``rte_extmem_*`` namespace.
+
+These API's are (as their name implies) intended to allow registering or
+unregistering externally allocated memory to/from DPDK's internal page table, to
+allow API's like ``rte_virt2memseg`` etc. to work with externally allocated
+memory. Memory added this way will not be available for any regular DPDK
+allocators; DPDK will leave this memory for the user application to manage.
+
+The expected workflow is as follows:
+
+* Get a pointer to memory area
+* Register memory within DPDK
+ - If IOVA table is not specified, IOVA addresses will be assumed to be
+ unavailable
+ - Other processes must attach to the memory area before they can use it
+* Perform DMA mapping with ``rte_dev_dma_map`` if needed
+* Use the memory area in your application
+* If memory area is no longer needed, it can be unregistered
+ - If the area was mapped for DMA, unmapping must be performed before
+ unregistering memory
+ - Other processes must detach from the memory area before it can be
+ unregistered
+
+Since these externally allocated memory areas will not be managed by DPDK, it is
+therefore up to the user application to decide how to use them and what to do
+with them once they're registered.
+