memzone: document reserving zero-length memzones

Currently, reserving a memzone with length set to 0 will not trigger
any memory allocations, and memzone will instead be looking through
already allocated memory only. Document this limitation.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>

diff --git a/lib/librte_eal/common/include/rte_memzone.h b/lib/librte_eal/common/include/rte_memzone.h
index 0eeb94f..a4c9bd6 100644 (file)
--- a/lib/librte_eal/common/include/rte_memzone.h
+++ b/lib/librte_eal/common/include/rte_memzone.h
@@ -77,6 +77,10 @@ struct rte_memzone {
  * correctly filled memzone descriptor. If the allocation cannot be
  * done, return NULL.
  *
+ * @note Reserving memzones with len set to 0 will only attempt to allocate
+ *   memzones from memory that is already available. It will not trigger any
+ *   new allocations.
+ *
  * @param name
  *   The name of the memzone. If it already exists, the function will
  *   fail and return NULL.
@@ -130,6 +134,10 @@ const struct rte_memzone *rte_memzone_reserve(const char *name,
  * descriptor. If the allocation cannot be done or if the alignment
  * is not a power of 2, returns NULL.
  *
+ * @note Reserving memzones with len set to 0 will only attempt to allocate
+ *   memzones from memory that is already available. It will not trigger any
+ *   new allocations.
+ *
  * @param name
  *   The name of the memzone. If it already exists, the function will
  *   fail and return NULL.
@@ -188,6 +196,10 @@ const struct rte_memzone *rte_memzone_reserve_aligned(const char *name,
  * boundary. That implies that requested length should be less or equal
  * then boundary.
  *
+ * @note Reserving memzones with len set to 0 will only attempt to allocate
+ *   memzones from memory that is already available. It will not trigger any
+ *   new allocations.
+ *
  * @param name
  *   The name of the memzone. If it already exists, the function will
  *   fail and return NULL.