Imported Upstream version 17.05

[deb_dpdk.git] / doc / guides / prog_guide / env_abstraction_layer.rst

diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst b/doc/guides/prog_guide/env_abstraction_layer.rst
index 10a10a8..fff1c06 100644 (file)
--- a/doc/guides/prog_guide/env_abstraction_layer.rst
+++ b/doc/guides/prog_guide/env_abstraction_layer.rst
@@ -178,8 +178,8 @@ The EAL also allows timed callbacks to be used in the same way as for NIC interr
 
 .. note::
 
-    In DPDK PMD, the only interrupts handled by the dedicated host thread are those for link status change,
-    i.e. link up and link down notification.
+    In DPDK PMD, the only interrupts handled by the dedicated host thread are those for link status change
+    (link up and link down notification) and for sudden device removal.
 
 
 + RX Interrupt Event
@@ -207,6 +207,23 @@ The eth_dev driver takes responsibility to program the latter mapping.
 The RX interrupt are controlled/enabled/disabled by ethdev APIs - 'rte_eth_dev_rx_intr_*'. They return failure if the PMD
 hasn't support them yet. The intr_conf.rxq flag is used to turn on the capability of RX interrupt per device.
 
++ Device Removal Event
+
+This event is triggered by a device being removed at a bus level. Its
+underlying resources may have been made unavailable (i.e. PCI mappings
+unmapped). The PMD must make sure that on such occurrence, the application can
+still safely use its callbacks.
+
+This event can be subscribed to in the same way one would subscribe to a link
+status change event. The execution context is thus the same, i.e. it is the
+dedicated interrupt host thread.
+
+Considering this, it is likely that an application would want to close a
+device having emitted a Device Removal Event. In such case, calling
+``rte_eth_dev_close()`` can trigger it to unregister its own Device Removal Event
+callback. Care must be taken not to close the device from the interrupt handler
+context. It is necessary to reschedule such closing operation.
+
 Blacklisting
 ~~~~~~~~~~~~
 
@@ -352,11 +369,6 @@ Known Issues
 
   3. It MUST not be used by multi-producer/consumer pthreads, whose scheduling policies are SCHED_FIFO or SCHED_RR.
 
-  ``RTE_RING_PAUSE_REP_COUNT`` is defined for rte_ring to reduce contention. It's mainly for case 2, a yield is issued after number of times pause repeat.
-
-  It adds a sched_yield() syscall if the thread spins for too long while waiting on the other thread to finish its operations on the ring.
-  This gives the preempted thread a chance to proceed and finish with the ring enqueue/dequeue operation.
-
 + rte_timer
 
   Running  ``rte_timer_manager()`` on a non-EAL pthread is not allowed. However, resetting/stopping the timer from a non-EAL pthread is allowed.