1.. SPDX-License-Identifier: GPL-2.0+
2
3=====================================================
4Linux Driver for Intel(R) Ethernet Network Connection
5=====================================================
6
7Intel Gigabit Linux driver.
8Copyright(c) 2008-2018 Intel Corporation.
9
10Contents
11========
12
13- Identifying Your Adapter
14- Command Line Parameters
15- Additional Configurations
16- Support
17
18
19Identifying Your Adapter
20========================
21For information on how to identify your adapter, and for the latest Intel
22network drivers, refer to the Intel Support website:
23https://www.intel.com/support
24
25
26Command Line Parameters
27=======================
28If the driver is built as a module, the following optional parameters are used
29by entering them on the command line with the modprobe command using this
30syntax::
31
32    modprobe e1000e [<option>=<VAL1>,<VAL2>,...]
33
34There needs to be a <VAL#> for each network port in the system supported by
35this driver. The values will be applied to each instance, in function order.
36For example::
37
38    modprobe e1000e InterruptThrottleRate=16000,16000
39
40In this case, there are two network ports supported by e1000e in the system.
41The default value for each parameter is generally the recommended setting,
42unless otherwise noted.
43
44NOTE: A descriptor describes a data buffer and attributes related to the data
45buffer. This information is accessed by the hardware.
46
47InterruptThrottleRate
48---------------------
49:Valid Range: 0,1,3,4,100-100000
50:Default Value: 3
51
52Interrupt Throttle Rate controls the number of interrupts each interrupt
53vector can generate per second. Increasing ITR lowers latency at the cost of
54increased CPU utilization, though it may help throughput in some circumstances.
55
56Setting InterruptThrottleRate to a value greater or equal to 100
57will program the adapter to send out a maximum of that many interrupts
58per second, even if more packets have come in. This reduces interrupt
59load on the system and can lower CPU utilization under heavy load,
60but will increase latency as packets are not processed as quickly.
61
62The default behaviour of the driver previously assumed a static
63InterruptThrottleRate value of 8000, providing a good fallback value for
64all traffic types, but lacking in small packet performance and latency.
65The hardware can handle many more small packets per second however, and
66for this reason an adaptive interrupt moderation algorithm was implemented.
67
68The driver has two adaptive modes (setting 1 or 3) in which
69it dynamically adjusts the InterruptThrottleRate value based on the traffic
70that it receives. After determining the type of incoming traffic in the last
71timeframe, it will adjust the InterruptThrottleRate to an appropriate value
72for that traffic.
73
74The algorithm classifies the incoming traffic every interval into
75classes.  Once the class is determined, the InterruptThrottleRate value is
76adjusted to suit that traffic type the best. There are three classes defined:
77"Bulk traffic", for large amounts of packets of normal size; "Low latency",
78for small amounts of traffic and/or a significant percentage of small
79packets; and "Lowest latency", for almost completely small packets or
80minimal traffic.
81
82 - 0: Off
83      Turns off any interrupt moderation and may improve small packet latency.
84      However, this is generally not suitable for bulk throughput traffic due
85      to the increased CPU utilization of the higher interrupt rate.
86 - 1: Dynamic mode
87      This mode attempts to moderate interrupts per vector while maintaining
88      very low latency. This can sometimes cause extra CPU utilization. If
89      planning on deploying e1000e in a latency sensitive environment, this
90      parameter should be considered.
91 - 3: Dynamic Conservative mode (default)
92      In dynamic conservative mode, the InterruptThrottleRate value is set to
93      4000 for traffic that falls in class "Bulk traffic". If traffic falls in
94      the "Low latency" or "Lowest latency" class, the InterruptThrottleRate is
95      increased stepwise to 20000. This default mode is suitable for most
96      applications.
97 - 4: Simplified Balancing mode
98      In simplified mode the interrupt rate is based on the ratio of TX and
99      RX traffic.  If the bytes per second rate is approximately equal, the
100      interrupt rate will drop as low as 2000 interrupts per second.  If the
101      traffic is mostly transmit or mostly receive, the interrupt rate could
102      be as high as 8000.
103 - 100-100000:
104      Setting InterruptThrottleRate to a value greater or equal to 100
105      will program the adapter to send at most that many interrupts per second,
106      even if more packets have come in. This reduces interrupt load on the
107      system and can lower CPU utilization under heavy load, but will increase
108      latency as packets are not processed as quickly.
109
110NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and
111RxAbsIntDelay parameters. In other words, minimizing the receive and/or
112transmit absolute delays does not force the controller to generate more
113interrupts than what the Interrupt Throttle Rate allows.
114
115RxIntDelay
116----------
117:Valid Range: 0-65535 (0=off)
118:Default Value: 0
119
120This value delays the generation of receive interrupts in units of 1.024
121microseconds. Receive interrupt reduction can improve CPU efficiency if
122properly tuned for specific network traffic. Increasing this value adds extra
123latency to frame reception and can end up decreasing the throughput of TCP
124traffic. If the system is reporting dropped receives, this value may be set
125too high, causing the driver to run out of available receive descriptors.
126
127CAUTION: When setting RxIntDelay to a value other than 0, adapters may hang
128(stop transmitting) under certain network conditions. If this occurs a NETDEV
129WATCHDOG message is logged in the system event log. In addition, the
130controller is automatically reset, restoring the network connection. To
131eliminate the potential for the hang ensure that RxIntDelay is set to 0.
132
133RxAbsIntDelay
134-------------
135:Valid Range: 0-65535 (0=off)
136:Default Value: 8
137
138This value, in units of 1.024 microseconds, limits the delay in which a
139receive interrupt is generated. This value ensures that an interrupt is
140generated after the initial packet is received within the set amount of time,
141which is useful only if RxIntDelay is non-zero. Proper tuning, along with
142RxIntDelay, may improve traffic throughput in specific network conditions.
143
144TxIntDelay
145----------
146:Valid Range: 0-65535 (0=off)
147:Default Value: 8
148
149This value delays the generation of transmit interrupts in units of 1.024
150microseconds. Transmit interrupt reduction can improve CPU efficiency if
151properly tuned for specific network traffic. If the system is reporting
152dropped transmits, this value may be set too high causing the driver to run
153out of available transmit descriptors.
154
155TxAbsIntDelay
156-------------
157:Valid Range: 0-65535 (0=off)
158:Default Value: 32
159
160This value, in units of 1.024 microseconds, limits the delay in which a
161transmit interrupt is generated. It is useful only if TxIntDelay is non-zero.
162It ensures that an interrupt is generated after the initial Packet is sent on
163the wire within the set amount of time. Proper tuning, along with TxIntDelay,
164may improve traffic throughput in specific network conditions.
165
166copybreak
167---------
168:Valid Range: 0-xxxxxxx (0=off)
169:Default Value: 256
170
171The driver copies all packets below or equaling this size to a fresh receive
172buffer before handing it up the stack.
173This parameter differs from other parameters because it is a single (not 1,1,1
174etc.) parameter applied to all driver instances and it is also available
175during runtime at /sys/module/e1000e/parameters/copybreak.
176
177To use copybreak, type::
178
179    modprobe e1000e.ko copybreak=128
180
181SmartPowerDownEnable
182--------------------
183:Valid Range: 0,1
184:Default Value: 0 (disabled)
185
186Allows the PHY to turn off in lower power states. The user can turn off this
187parameter in supported chipsets.
188
189KumeranLockLoss
190---------------
191:Valid Range: 0,1
192:Default Value: 1 (enabled)
193
194This workaround skips resetting the PHY at shutdown for the initial silicon
195releases of ICH8 systems.
196
197IntMode
198-------
199:Valid Range: 0-2
200:Default Value: 0
201
202   +-------+----------------+
203   | Value | Interrupt Mode |
204   +=======+================+
205   |   0   |     Legacy     |
206   +-------+----------------+
207   |   1   |       MSI      |
208   +-------+----------------+
209   |   2   |      MSI-X     |
210   +-------+----------------+
211
212IntMode allows load time control over the type of interrupt registered for by
213the driver. MSI-X is required for multiple queue support, and some kernels and
214combinations of kernel .config options will force a lower level of interrupt
215support.
216
217This command will show different values for each type of interrupt::
218
219  cat /proc/interrupts
220
221CrcStripping
222------------
223:Valid Range: 0,1
224:Default Value: 1 (enabled)
225
226Strip the CRC from received packets before sending up the network stack. If
227you have a machine with a BMC enabled but cannot receive IPMI traffic after
228loading or enabling the driver, try disabling this feature.
229
230WriteProtectNVM
231---------------
232:Valid Range: 0,1
233:Default Value: 1 (enabled)
234
235If set to 1, configure the hardware to ignore all write/erase cycles to the
236GbE region in the ICHx NVM (in order to prevent accidental corruption of the
237NVM). This feature can be disabled by setting the parameter to 0 during initial
238driver load.
239
240NOTE: The machine must be power cycled (full off/on) when enabling NVM writes
241via setting the parameter to zero. Once the NVM has been locked (via the
242parameter at 1 when the driver loads) it cannot be unlocked except via power
243cycle.
244
245Debug
246-----
247:Valid Range: 0-16 (0=none,...,16=all)
248:Default Value: 0
249
250This parameter adjusts the level of debug messages displayed in the system logs.
251
252
253Additional Features and Configurations
254======================================
255
256Jumbo Frames
257------------
258Jumbo Frames support is enabled by changing the Maximum Transmission Unit (MTU)
259to a value larger than the default value of 1500.
260
261Use the ifconfig command to increase the MTU size. For example, enter the
262following where <x> is the interface number::
263
264    ifconfig eth<x> mtu 9000 up
265
266Alternatively, you can use the ip command as follows::
267
268    ip link set mtu 9000 dev eth<x>
269    ip link set up dev eth<x>
270
271This setting is not saved across reboots. The setting change can be made
272permanent by adding 'MTU=9000' to the file:
273
274- For RHEL: /etc/sysconfig/network-scripts/ifcfg-eth<x>
275- For SLES: /etc/sysconfig/network/<config_file>
276
277NOTE: The maximum MTU setting for Jumbo Frames is 8996. This value coincides
278with the maximum Jumbo Frames size of 9018 bytes.
279
280NOTE: Using Jumbo frames at 10 or 100 Mbps is not supported and may result in
281poor performance or loss of link.
282
283NOTE: The following adapters limit Jumbo Frames sized packets to a maximum of
2844088 bytes:
285
286  - Intel(R) 82578DM Gigabit Network Connection
287  - Intel(R) 82577LM Gigabit Network Connection
288
289The following adapters do not support Jumbo Frames:
290
291  - Intel(R) PRO/1000 Gigabit Server Adapter
292  - Intel(R) PRO/1000 PM Network Connection
293  - Intel(R) 82562G 10/100 Network Connection
294  - Intel(R) 82562G-2 10/100 Network Connection
295  - Intel(R) 82562GT 10/100 Network Connection
296  - Intel(R) 82562GT-2 10/100 Network Connection
297  - Intel(R) 82562V 10/100 Network Connection
298  - Intel(R) 82562V-2 10/100 Network Connection
299  - Intel(R) 82566DC Gigabit Network Connection
300  - Intel(R) 82566DC-2 Gigabit Network Connection
301  - Intel(R) 82566DM Gigabit Network Connection
302  - Intel(R) 82566MC Gigabit Network Connection
303  - Intel(R) 82566MM Gigabit Network Connection
304  - Intel(R) 82567V-3 Gigabit Network Connection
305  - Intel(R) 82577LC Gigabit Network Connection
306  - Intel(R) 82578DC Gigabit Network Connection
307
308NOTE: Jumbo Frames cannot be configured on an 82579-based Network device if
309MACSec is enabled on the system.
310
311
312ethtool
313-------
314The driver utilizes the ethtool interface for driver configuration and
315diagnostics, as well as displaying statistical information. The latest ethtool
316version is required for this functionality. Download it at:
317
318https://www.kernel.org/pub/software/network/ethtool/
319
320NOTE: When validating enable/disable tests on some parts (for example, 82578),
321it is necessary to add a few seconds between tests when working with ethtool.
322
323
324Speed and Duplex Configuration
325------------------------------
326In addressing speed and duplex configuration issues, you need to distinguish
327between copper-based adapters and fiber-based adapters.
328
329In the default mode, an Intel(R) Ethernet Network Adapter using copper
330connections will attempt to auto-negotiate with its link partner to determine
331the best setting. If the adapter cannot establish link with the link partner
332using auto-negotiation, you may need to manually configure the adapter and link
333partner to identical settings to establish link and pass packets. This should
334only be needed when attempting to link with an older switch that does not
335support auto-negotiation or one that has been forced to a specific speed or
336duplex mode. Your link partner must match the setting you choose. 1 Gbps speeds
337and higher cannot be forced. Use the autonegotiation advertising setting to
338manually set devices for 1 Gbps and higher.
339
340Speed, duplex, and autonegotiation advertising are configured through the
341ethtool utility.
342
343Caution: Only experienced network administrators should force speed and duplex
344or change autonegotiation advertising manually. The settings at the switch must
345always match the adapter settings. Adapter performance may suffer or your
346adapter may not operate if you configure the adapter differently from your
347switch.
348
349An Intel(R) Ethernet Network Adapter using fiber-based connections, however,
350will not attempt to auto-negotiate with its link partner since those adapters
351operate only in full duplex and only at their native speed.
352
353
354Enabling Wake on LAN (WoL)
355--------------------------
356WoL is configured through the ethtool utility.
357
358WoL will be enabled on the system during the next shut down or reboot. For
359this driver version, in order to enable WoL, the e1000e driver must be loaded
360prior to shutting down or suspending the system.
361
362NOTE: Wake on LAN is only supported on port A for the following devices:
363- Intel(R) PRO/1000 PT Dual Port Network Connection
364- Intel(R) PRO/1000 PT Dual Port Server Connection
365- Intel(R) PRO/1000 PT Dual Port Server Adapter
366- Intel(R) PRO/1000 PF Dual Port Server Adapter
367- Intel(R) PRO/1000 PT Quad Port Server Adapter
368- Intel(R) Gigabit PT Quad Port Server ExpressModule
369
370
371Support
372=======
373For general information, go to the Intel support website at:
374https://www.intel.com/support/
375
376If an issue is identified with the released source code on a supported kernel
377with a supported adapter, email the specific information related to the issue
378to intel-wired-lan@lists.osuosl.org.
379