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Manual Pages  — ENA


ena – FreeBSD kernel driver for Elastic Network Adapter (ENA) family



To compile this driver into the kernel, place the following line in your kernel configuration file: device ena

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):



The ENA is a networking interface designed to make good use of modern CPU features and system architectures.

The ENA device exposes a lightweight management interface with a minimal set of memory mapped registers and extendable command set through an Admin Queue.

The driver supports a range of ENA devices, is link-speed independent (i.e., the same driver is used for 10GbE, 25GbE, 40GbE, etc.), and has a negotiated and extendable feature set.

Some ENA devices support SR-IOV. This driver is used for both the SR-IOV Physical Function (PF) and Virtual Function (VF) devices.

The ENA devices enable high speed and low overhead network traffic processing by providing multiple Tx/Rx queue pairs (the maximum number is advertised by the device via the Admin Queue), a dedicated MSI-X interrupt vector per Tx/Rx queue pair, and CPU cacheline optimized data placement.

The ena driver supports industry standard TCP/IP offload features such as checksum offload and TCP transmit segmentation offload (TSO). Receive-side scaling (RSS) is supported for multi-core scaling.

The ena driver and its corresponding devices implement health monitoring mechanisms such as watchdog, enabling the device and driver to recover in a manner transparent to the application, as well as debug logs.

Some of the ENA devices support a working mode called Low-latency Queue (LLQ), which saves several more microseconds. This feature will be implemented for driver in future releases.


Supported PCI vendor ID/device IDs:


Device initialization phase:

ena%d: failed to init mmio read less

Error occurred during initialization of the mmio register read request.

ena%d: Can not reset device

Device could not be reset; device may not be responding or is already during reset.

ena%d: device version is too low

Version of the controller is too low and it is not supported by the driver.

ena%d: Invalid dma width value %d

The controller is able to request dma transcation width. Device stopped responding or it demanded invalid value.

ena%d: Can not initialize ena admin queue with device

Initialization of the Admin Queue failed; device may not be responding or there was a problem with initialization of the resources.

ena%d: Cannot get attribute for ena device rc: %d

Failed to get attributes of the device from the controller.

ena%d: Cannot configure aenq groups rc: %d

Errors occurred when trying to configure AENQ groups.

Driver initialisation/shutdown phase:

ena%d: PCI resource allocation failed!
ena%d: allocating ena_dev failed
ena%d: failed to pmap registers bar
ena%d: Error while setting up bufring
ena%d: Error with initialization of IO rings
ena%d: can not allocate ifnet structure
ena%d: Error with network interface setup
ena%d: Failed to enable and set the admin interrupts
ena%d: Failed to allocate %d, vectors %d
ena%d: Failed to enable MSIX, vectors %d rc %d
ena%d: Error with MSI-X enablement
ena%d: could not allocate irq vector: %d
ena%d: Unable to allocate bus resource: registers

Resource allocation failed when initializing the device; driver will not be attached.

ena%d: ENA device init failed (err: %d)

Device initialization failed; driver will not be attached.

ena%d: could not activate irq vector: %d

Error occurred when trying to activate interrupt vectors for Admin Queue.

ena%d: failed to register interrupt handler for irq %ju: %d

Error occurred when trying to register Admin Queue interrupt handler.

ena%d: Cannot setup mgmnt queue intr

Error occurred during configuration of the Admin Queue interrupts.

ena%d: Enable MSI-X failed

Configuration of the MSI-X for Admin Queue failed; there could be lack of resources or interrupts could not have been configured; driver will not be attached.

ena%d: VLAN is in use, detach first

VLANs are being used when trying to detach the driver; VLANs should be detached first and then detach routine should be called again.

ena%d: Unmapped RX DMA tag associations
ena%d: Unmapped TX DMA tag associations

Error occurred when trying to destroy RX/TX DMA tag.

ena%d: Cannot init RSS
ena%d: Cannot fill indirect table
ena%d: Cannot fill indirect table
ena%d: Cannot fill hash function
ena%d: Cannot fill hash control
ena%d: WARNING: RSS was not properly initialized, it will affect bandwidth

Error occurred during initialization of one of RSS resources; device is still going to work but it will affect performance because all RX packets will be passed to queue 0 and there will be no hash information.

ena%d: failed to tear down irq: %d
ena%d: dev has no parent while releasing res for irq: %d
  Release of the interrupts failed.

Additional diagnostic:

ena%d: Cannot get attribute for ena device

This message appears when trying to change MTU and driver is unable to get attributes from the device.

ena%d: Invalid MTU setting. new_mtu: %d

Requested MTU value is not supported and will not be set.

ena%d: keep alive watchdog timeout

Device stopped responding and will be reset.

ena%d: Found a Tx that wasn't completed on time, qid %d, index %d.

Packet was pushed to the NIC but not sent within given time limit; it may be caused by hang of the IO queue.

ena%d: The number of lost tx completion is aboce the threshold (%d > %d). Reset the device

If too many Tx wasn't completed on time the device is going to be reset; it may be caused by hanged queue or device.

ena%d: trigger reset is on

Device will be reset; reset is triggered either by watchdog or if too many TX packets were not completed on time.

ena%d: invalid value recvd

Link status received from the device in the AENQ handler is invalid.

ena%d: Allocation for Tx Queue %u failed
ena%d: Allocation for Rx Queue %u failed
ena%d: Unable to create Rx DMA map for buffer %d
ena%d: Failed to create io TX queue #%d rc: %d
ena%d: Failed to get TX queue handlers. TX queue num %d rc: %d
ena%d: Failed to create io RX queue[%d] rc: %d
ena%d: Failed to get RX queue handlers. RX queue num %d rc: %d
ena%d: failed to request irq
ena%d: could not allocate irq vector: %d
ena%d: failed to register interrupt handler for irq %ju: %d

IO resources initialization failed. Interface will not be brought up.

ena%d: LRO[%d] Initialization failed!

Initialization of the LRO for the RX ring failed.

ena%d: failed to alloc buffer for rx queue
ena%d: failed to add buffer for rx queue %d
ena%d: refilled rx queue %d with %d pages only

Allocation of resources used on RX path failed; if happened during initialization of the IO queue, the interface will not be brought up.

ena%d: ioctl promisc/allmulti

IOCTL request for the device to work in promiscuous/allmulti mode; see ifconfig(8) for more details.

ena%d: too many fragments. Last fragment: %d!

Packet with unsupported number of segments was queued for sending to the device; packet will be dropped.


If an issue is identified with the released source code with a supported adapter email the specific information related to the issue to <Mt mk@semihalf.com> and <Mt mw@semihalf.com>.


vlan(4), ifconfig(8)


The ena driver was written by Semihalf.

ENA (4) May 04, 2017

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