Commit Graph

44 Commits

Author SHA1 Message Date
Warner Losh
329e817fcc Reapply, with minor tweaks, r338025, from the original commit:
Remove unused and easy to misuse PNP macro parameter

Inspired by r338025, just remove the element size parameter to the
MODULE_PNP_INFO macro entirely.  The 'table' parameter is now required to
have correct pointer (or array) type.  Since all invocations of the macro
already had this property and the emitted PNP data continues to include the
element size, there is no functional change.

Mostly done with the coccinelle 'spatch' tool:

  $ cat modpnpsize0.cocci
    @normaltables@
    identifier b,c;
    expression a,d,e;
    declarer MODULE_PNP_INFO;
    @@
     MODULE_PNP_INFO(a,b,c,d,
    -sizeof(d[0]),
     e);

    @singletons@
    identifier b,c,d;
    expression a;
    declarer MODULE_PNP_INFO;
    @@
     MODULE_PNP_INFO(a,b,c,&d,
    -sizeof(d),
     1);

  $ rg -l MODULE_PNP_INFO -- sys | \
    xargs spatch --in-place --sp-file modpnpsize0.cocci

(Note that coccinelle invokes diff(1) via a PATH search and expects diff to
tolerate the -B flag, which BSD diff does not.  So I had to link gdiff into
PATH as diff to use spatch.)

Tinderbox'd (-DMAKE_JUST_KERNELS).
Approved by: re (glen)
2018-09-26 17:12:14 +00:00
Conrad Meyer
b8e771e97a Back out r338035 until Warner is finished churning GSoC PNP patches
I was not aware Warner was making or planning to make forward progress in
this area and have since been informed of that.

It's easy to apply/reapply when churn dies down.
2018-08-19 00:46:22 +00:00
Conrad Meyer
faa319436f Remove unused and easy to misuse PNP macro parameter
Inspired by r338025, just remove the element size parameter to the
MODULE_PNP_INFO macro entirely.  The 'table' parameter is now required to
have correct pointer (or array) type.  Since all invocations of the macro
already had this property and the emitted PNP data continues to include the
element size, there is no functional change.

Mostly done with the coccinelle 'spatch' tool:

  $ cat modpnpsize0.cocci
    @normaltables@
    identifier b,c;
    expression a,d,e;
    declarer MODULE_PNP_INFO;
    @@
     MODULE_PNP_INFO(a,b,c,d,
    -sizeof(d[0]),
     e);

    @singletons@
    identifier b,c,d;
    expression a;
    declarer MODULE_PNP_INFO;
    @@
     MODULE_PNP_INFO(a,b,c,&d,
    -sizeof(d),
     1);

  $ rg -l MODULE_PNP_INFO -- sys | \
    xargs spatch --in-place --sp-file modpnpsize0.cocci

(Note that coccinelle invokes diff(1) via a PATH search and expects diff to
tolerate the -B flag, which BSD diff does not.  So I had to link gdiff into
PATH as diff to use spatch.)

Tinderbox'd (-DMAKE_JUST_KERNELS).
2018-08-19 00:22:21 +00:00
Warner Losh
b60a815e6d Remove stray space from PNP string. 2018-07-08 23:12:27 +00:00
Warner Losh
40abe76bf0 Add PNP info to PCI attachment of ena driver
Make unsigned values uint16_t for pnp table. They are properly
uint16_t befause they are 16-bit PCI IDs. The PNP_INFO language has no
type for bare unsigned.

Reviewed by: imp, chuck
Submitted by: Lakhan Shiva Kamireddy <lakhanshiva@gmail.com>
Sponsored by: Google, Inc. (GSoC 2018)
Pull Request: https://github.com/bsdimp/freebsd/pull/5
2018-07-08 20:39:38 +00:00
Marcin Wojtas
2339f28c6e Do not pass header length to the ENA controller
Header length is optional hint for the ENA device. Because It is not
guaranteed that every packet header will be in the first mbuf
segment, it is better to skip passing any information. If the header
length will be indicating invalid value (different than 0), then the
packet will be dropped.

This kind situation can appear, when the UDP packet will be fragmented
by the stack in the ip_fragment() function.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reported by:  Krishna Yenduri <kyenduri@brkt.com>
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
2018-05-10 09:37:54 +00:00
Marcin Wojtas
dbf2eb543b Skip setting the MTU for ENA if it is not changing
On AWS, a network interface can get reinitialized every 30 minutes due
to the MTU being (re)set when a new DHCP lease is obtained. This can
cause packet drop, along with annoying syslog messages.

Skip setting the MTU in the ena driver if the new MTU is the same as the
old MTU. Note this fix is already in the netfront driver.

Testing: Verified ena up/down messages do not appear every 30 min in
/var/log/messages with the fix in place.

Submitted by:   Krishna Yenduri <kyenduri@brkt.com>
Reviewed by: Michal Krawczyk <mk@semihalf.com>
2018-05-10 09:32:59 +00:00
Marcin Wojtas
fbb0ed71b2 Upgrade ENA version to v0.8.1
Submitted by: Michal Krawczyk <mk@semihalf.com>
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
2018-05-10 09:06:21 +00:00
Marcin Wojtas
5727f16270 Fix setting AENQ group in ENA driver
With the current state of the AENQ handlers in the ENA driver, only
implemented handlers should be indicated.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12872
2017-11-09 13:38:17 +00:00
Marcin Wojtas
4727bda6f2 Allow usage of more RX descriptors than 1 in ENA driver
Using only 1 descriptor on RX could be an issue, if system would be low
on resources and could not provide driver with large chunks of
contiguous memory.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12871
2017-11-09 13:36:42 +00:00
Marcin Wojtas
3cfadb28c3 Read max MTU from the ENA device
The device now provides driver with max available MTU value it
can handle.

The function setting MTU for the interface was simplified and reworked
to follow up this changes.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12870
2017-11-09 13:35:07 +00:00
Marcin Wojtas
ad5a5afaad Fix calculating io queues number in ENA driver
The maximum number of io_cq was the same number as maximum io_sq
indicated by the device working in normal mode (without LLQ).
It is not always true, especially when LLQ is being enabled.
Fix it.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12869
2017-11-09 13:33:02 +00:00
Marcin Wojtas
4e8acd844f Rework printouts and logging level in ENA driver
The driver was printing out a lot of information upon failure, which
does not have to be interested for the user.
Changing logging level required to rebuild driver with proper flags. The
proper sysctl was added, so the level now can be changed dynamically
using bitmask.

Levels of printouts were adjusted to keep on mind end user instead of
debugging purposes.

More verbose messages were added to align the driver with the Linux.

Fix building error introduced by the r325506 by casting csum_flags to
uint64_t.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12868
2017-11-09 13:30:39 +00:00
Marcin Wojtas
bfea0e9327 Fix comparing L3 type with L4 enum on RX hash in ENA driver
This bug wasn't impacting anything, because both enums are indicating
the same value, but it could cause a problem on API change.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12867
2017-11-09 12:39:26 +00:00
Marcin Wojtas
90f4da8bd4 Fix compilation warnings when building ENA driver with gcc compiler
The gcc compiler is more sensitive when variable is having an value
assigned, but it is not used anywhere further.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: rlibby
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12866
2017-11-09 12:37:19 +00:00
Marcin Wojtas
cd43338509 Fix checking if the DF flag was set in ENA driver
The previous way of checking for DF was not valid.
When DF is enabled, the DF bit should be 1.

The original way of checking it was wrong in 2 ways: first of all, it
was not checking for single bit, secondly, it was checking for 0.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12865
2017-11-09 12:32:10 +00:00
Marcin Wojtas
5a9902126e Cleanup of the ENA driver header file
Remove unused macros and fields - some of them were only initialized,
without further usage.

Implement minor style fixes and add required comments.

On the occasion add missing TX completion counter, which was existing,
but mistakenly remained unused.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12864
2017-11-09 12:07:02 +00:00
Marcin Wojtas
8805021a2a Allow partial MSI-x allocation in ENA driver
The situation, where part of the MSI-x was not configured properly, was
not properly handled. Now, the driver reduces number of queues to
reflect number of existing and properly configured MSI-x vectors.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12863
2017-11-09 12:03:06 +00:00
Marcin Wojtas
0052f3b580 Remove deprecated and unused counters in ENA driver
Few counters were imported from the Linux driver and never used,
because of differences between the Linux and FreeBSD APIs.

Queue stops and resumes are no longer supported by the driver and
counters were incremented indicating false events.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: rlibby
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12862
2017-11-09 12:01:46 +00:00
Marcin Wojtas
3f9ed7ab94 Cover ENA driver code with branch predictioning statements
The driver was using it in only few places, so the rest of the code
was covered with those statement.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: rlibby
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12861
2017-11-09 11:59:21 +00:00
Marcin Wojtas
0bdffe5959 Refactor style of the ENA driver
* Change all conditional checks in "if" statement to boolean expressions
* Initialize variables with too complex values outside the declaration
* Fix indentations
* Move code associated with sysctls to ena_sysctl.c file
* For consistency, remove unnecesary "return" from void functions
* Use if_getdrvflags() function instead of accesing variable directly

Submitted by: Michal Krawczyk <mk@semihalf.com>
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12860
2017-11-09 11:57:02 +00:00
Marcin Wojtas
7d2544e60e Fix error handling in the ENA driver and lock drbr_free() call
Some goto tags were renamed for consistency, and few error handling
routines were reworked.

The drbr_free() must be locked just in case code will change in the
future - for now, it should never be an issue, because drbr is being
flushed in the ena_down() call, and the lock is required only when there
are some mbufs inside.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12859
2017-11-09 11:54:32 +00:00
Marcin Wojtas
197f028470 Destroy admin queue after freeing interrupts in ENA driver
On heavy load, when interrupt handling routine was slowed down, there
could appear memory corruption, because resources were destroyed and
interrupt was still being handled.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12858
2017-11-09 11:52:52 +00:00
Marcin Wojtas
74dba3ad78 Split function checking for missing TX completion in ENA driver
Pure cosmetic change for better readability of the driver.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12857
2017-11-09 11:50:52 +00:00
Marcin Wojtas
efe6ab18da Check for Rx ring state to prevent from stall in the ENA driver
In case when Rx ring is full and driver will fail to allocate Rx mbufs,
the ring could be stalled.

Keep alive is checking every second for Rx ring state, and if it is full
for two cycles, then trigger rx_cleanup routine in another thread.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12856
2017-11-09 11:48:22 +00:00
Marcin Wojtas
43fefd1629 Add RX OOO completion feature
The RX out of order completion feature, allows to complete RX
descriptors out of order, by keeping trace of all free descriptors in
the separate array.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12855
2017-11-09 11:45:59 +00:00
Marcin Wojtas
fceb938715 Change function validate_tx_req_id() to inline in ENA driver
The function is in hot path of the driver (TX) and asking compiler for
making this function inline was changed for consistency and higher
readability.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: rlibby, byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D12854
2017-11-07 13:26:11 +00:00
Marcin Wojtas
cd5d5804b1 Fix ENA driver error handling in attach and basic style fixes
The patch contains following changes:

* In conditional checks, always check for NULL or 0 instead of negating values
* Use malloc and free explicitely, instead of ENA_MEM_FREE and ENA_MEM_FREE (the
  dmadev passed to macro is never used, and could be a little misleading)
* Always check for NULL after calling malloc (few checks were missing)
* Rework naming of the goto tags in ena_attach() for consistency
* Fix error handling in ena_attach() - few goto instructions were leading to the
  wrong tag
* Destroy MMIO req read request if attach failed
* Remove checking for NULL after calling malloc with M_WAITOK flag

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: byenduri_gmail.com
Obtained from: Semihalf
Sponsored by: Amazon.com, Inc.
Differential Revision: https://reviews.freebsd.org/D12853
2017-11-07 13:20:41 +00:00
Marcin Wojtas
30217e2dff Rework counting of hardware statistics in ENA driver
Do not read all statistics from the device, instead count them in the
driver except from RX drops - they are received directly from the NIC
in the AENQ descriptor.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Reviewed by: imp
Obtained from: Semihalf
Sponsored by: Amazon.com, Inc.
Differential Revision: https://reviews.freebsd.org/D12852
2017-10-31 16:31:23 +00:00
Marcin Wojtas
a195fab02b Update ena-com HAL to v1.1.4.3 and update driver accordingly
The newest ena-com HAL supports LLQv2 and introduces
API changes. In order not to break the driver compilation
it was updated/fixed in a following way:

* Change version of the driver to 0.8.0
* Provide reset cause when triggering reset of the device
* Reset device after attach fails
* In the reset task free management irq after calling ena_down. Admin
  queue can still be used before ena_down is called, or when it is
  being handled
* Do not reset device if ena_reset_task fails
* Move call of the ena_com_dev_reset to the ena_down() routine - it
  should be called only if interface was up
* Use different function for checking empty space on the sq ring
  (ena-com API change)
* Fix typo on ENA_TX_CLEANUP_THRESHOLD
* Change checking for EPERM with EOPNOTSUPP - change in the ena-com API
* Minor style fixes

Submitted by: Michal Krawczyk <mk@semihalf.com>
Obtained from: Amazon.com, Inc.
               Semihalf
Sponsored by: Amazon.com, Inc.
Differential Revision: https://reviews.freebsd.org/D12143
2017-10-31 12:41:07 +00:00
Zbigniew Bodek
516d335588 Fix error check for Rx mbuf allocation in ENA driver
ena_alloc_rx_mbuf() will return positive error code
on failure. Act accordingly.

Submitted by: Krishna Yenduri <kyenduri at brkt.com>
2017-07-10 22:11:30 +00:00
Zbigniew Bodek
1b069f1c69 Replace mbuf defragmentation with collapse
Collapse should be more effective than defragmentation.
Added missing declaration of ena_check_and_collapse_mbuf().

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
2017-07-04 00:10:29 +00:00
Zbigniew Bodek
8a573700af Fix creation of dma tags and TSO settings
TSO settings were not reflecting real HW capabilities.

DMA tags were created with wrong window - high address was the same as
low, so excluding window was not working.

Capabilities of TX dma transaction were not set properly - TSO max size
had been increased and size of one segment had been adjusted.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
2017-07-04 00:08:47 +00:00
Zbigniew Bodek
63b4364a9a Remove RX mtx from ENA driver
RX lock is no longer required. There can only be one RX cleanup task
running at a time, RX cleanup cannot be executed if interface is not
yet initialized and ena_down() will not free any RX resources if any io
interrupt is being handled - RX cleanup task is only called from an
interrupt handler.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
2017-07-04 00:06:56 +00:00
Zbigniew Bodek
b4b2903275 Call drbr_advance() before leaving TX routine
If drbr_advance() is not called before doing cleanup and packet is
already enqueued for sending (tx_info is holding pointer to mbuf), then
mbuf is cleaned both in drbr_flush() and in cleanup routine, when all
mbufs hold by tx_buffer_info are being released.

This causes panic, because mbuf is released twice.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
2017-07-04 00:04:31 +00:00
Zbigniew Bodek
93471047c0 Unmask all IO irqs after driver state is set as running
If driver left MSI-x handlling routine because interface was put down,
it is not unmasking IRQs, so any requesting interrupt will be awaiting
for unmasking.

On ena_up() routine all interrupts are being unmasked and any awaiting
interrupt will be handled right away.

If handler was executed before driver state was set as running, handling
routine is being ended immediately, leaving IO irqs for given queue
masked.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
2017-07-04 00:02:28 +00:00
Zbigniew Bodek
b38cf61385 Acquire locks before calling drbr_flush()
It is required to hold lock that is associated with buffer ring before
flushing drbr.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
2017-07-04 00:00:42 +00:00
Zbigniew Bodek
3d3a90f9ab Add missing lock upon initialization of the interface
Lack of this lock was causing crash if down was called in
parallel with the initialization routine.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
2017-07-03 23:59:11 +00:00
Zbigniew Bodek
416e886499 Introduce additional locks when releasing TX resources and buffers in ENA
There could be race condition with TX cleaning routine when cleaning mbufs,
when it was called directly from main sending thread (ena_mq_start).

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
Differential revision: https://reviews.freebsd.org/D10927
2017-05-30 12:00:56 +00:00
Zbigniew Bodek
b9252a8889 Move ENA's hw stats updating routine to separate task
Initially, stats were being updated each time OS was requesting for
the first statistic.
To read statistics from hw, condvar was used. cv_timedwait cannot be
called when unsleepable lock is held, and this happens when FreeBSD
is requesting statistic.
Seperate task is reading statistics from NIC each 1 second.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
Differential revision: https://reviews.freebsd.org/D10926
2017-05-30 11:58:51 +00:00
Zbigniew Bodek
081169f24c Add error handling to the ENA driver if init of the reset task fails
Also, to simplify cleaning routine, reset task is initialized before
allocating statistics and other resources.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
Differential revision: https://reviews.freebsd.org/D10925
2017-05-30 11:56:54 +00:00
Zbigniew Bodek
e67c655431 Add locks before each ena_up and ena_down
Lock only ena_up and ena_down calls in ioctl handler, instead of whole
ioctl. Locking ioctl with sx lock that is sleepable, is not allowed in
some cases, e.g. when multicast options are being changed.
Additional locking was added in deatch function to prevent race condition
with ioctl function.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
Differential revision: https://reviews.freebsd.org/D10924
2017-05-30 11:55:02 +00:00
Zbigniew Bodek
1e9fb89962 Add mbuf defragmentation to the ENA driver
When mbuf chain is too long and device cannot handle that number
of segments in DMA transaction, mbuf chain will be defragmented.
Initially, driver was dropping all mbuf chains that were exceeding
supported number of segments.

Submitted by:   Michal Krawczyk <mk@semihalf.com>
Obtained from:  Semihalf
Sponsored by:   Amazon.com Inc.
Differential revision: https://reviews.freebsd.org/D10923
2017-05-30 11:53:18 +00:00
Zbigniew Bodek
9b8d05b8ac Add support for Amazon Elastic Network Adapter (ENA) NIC
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.

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.

Submitted by:	Michal Krawczyk <mk@semihalf.com>
		Jakub Palider <jpa@semihalf.com>
		Jan Medala <jan@semihalf.com>
Obtained from: Semihalf
Sponsored by: Amazon.com Inc.
Differential revision: https://reviews.freebsd.org/D10427
2017-05-22 14:46:13 +00:00