diff --git a/PORTING.md b/PORTING.md
index 06b25a527e..474a7f5836 100644
--- a/PORTING.md
+++ b/PORTING.md
@@ -1,21 +1,22 @@
 SPDK Porting Guide
 ==================
 
-SPDK is ported to new environments by implementing the nvme_impl
-interface.  The nvme_impl interface provides APIs for the driver
+SPDK is ported to new environments by implementing the *env*
+library interface.  The *env* interface provides APIs for drivers
 to allocate physically contiguous and pinned memory, perform PCI
 operations (config cycles and mapping BARs), virtual to physical
-address translation and allocating per I/O data structures.
+address translation and managing memory pools.  The *env* API is
+defined in `[include/spdk/env.h](include/spdk/env.h)`.
 
-SPDK includes a default implementation of the nvme_impl API based
-on the Data Plane Development Kit ([DPDK](dpdk.org)).  This DPDK
-implementation can be found in lib/nvme/nvme_impl.h.  DPDK is
+SPDK includes a default implementation of the *env* library based
+on the Data Plane Development Kit ([DPDK](http://dpdk.org/)).
+This DPDK implementation can be found in `lib/env`.  DPDK is
 currently supported on Linux and FreeBSD only.
 
 Users who want to use SPDK on other operating system, or in
 userspace driver frameworks other than DPDK, will need to implement
-a new version of nvme_impl.h.  The new nvme_impl.h can be
+a new version of the *env* library.  The new implementation can be
 integrated into the SPDK build by updating the following line
 in CONFIG:
 
-    CONFIG_NVME_IMPL=nvme_impl.h
+    CONFIG_ENV?=$(SPDK_ROOT_DIR)/lib/env