work correctly, provided the BIOS supports HPET.
**Driver/Module**:
- ``lib/librte_eal/common/include/rte_cycles.h``
+ ``lib/librte_eal/include/rte_cycles.h``
Not all variants of supported NIC types have been used in testing
**Driver/Module**:
ALL.
+
+
+Unsuitable IOVA mode may be picked as the default
+-------------------------------------------------
+
+**Description**
+ Not all kernel drivers and not all devices support all IOVA modes. EAL will
+ attempt to pick a reasonable default based on a number of factors, but there
+ may be cases where the default may be unsuitable (for example, hotplugging
+ devices using `igb_uio` driver while having picked IOVA as VA mode on EAL
+ initialization).
+
+**Implication**
+ Some devices (hotplugged or otherwise) may not work due to incompatible IOVA
+ mode being automatically picked by EAL.
+
+**Resolution/Workaround**:
+ It is possible to force EAL to pick a particular IOVA mode by using the
+ `--iova-mode` command-line parameter. If conflicting requirements are present
+ (such as one device requiring IOVA as PA and one requiring IOVA as VA mode),
+ there is no workaround.
+
+**Affected Environment/Platform**:
+ Linux.
+
+**Driver/Module**:
+ ALL.
+
+Vhost multi-queue reconnection failed with QEMU version >= 4.2.0
+----------------------------------------------------------------
+
+**Description**
+ It's a QEMU regression bug (bad commit: c6beefd674ff). QEMU only saves
+ acked features for one vhost-net when vhost quits. When vhost reconnects
+ to virtio-net/virtio-pmd in multi-queue situations, the features been
+ set multiple times are not consistent.
+
+**Implication**
+ Vhost cannot reconnect back to virtio-net/virtio-pmd normally.
+
+**Resolution/Workaround**:
+ It is possible to filter the incorrect acked features at vhost-user side.
+
+**Affected Environment/Platform**:
+ ALL.
+
+**Driver/Module**:
+ Virtual Device Poll Mode Driver (PMD).