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/Documentation/networking/e1000.txt

https://gitlab.com/vibisreenivasan/UML
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  1Linux* Base Driver for Intel(R) Ethernet Network Connection
  2===========================================================
  3
  4Intel Gigabit Linux driver.
  5Copyright(c) 1999 - 2013 Intel Corporation.
  6
  7Contents
  8========
  9
 10- Identifying Your Adapter
 11- Command Line Parameters
 12- Speed and Duplex Configuration
 13- Additional Configurations
 14- Support
 15
 16Identifying Your Adapter
 17========================
 18
 19For more information on how to identify your adapter, go to the Adapter &
 20Driver ID Guide at:
 21
 22    http://support.intel.com/support/go/network/adapter/idguide.htm
 23
 24For the latest Intel network drivers for Linux, refer to the following
 25website.  In the search field, enter your adapter name or type, or use the
 26networking link on the left to search for your adapter:
 27
 28    http://support.intel.com/support/go/network/adapter/home.htm
 29
 30Command Line Parameters
 31=======================
 32
 33The default value for each parameter is generally the recommended setting,
 34unless otherwise noted.
 35
 36NOTES:  For more information about the AutoNeg, Duplex, and Speed
 37        parameters, see the "Speed and Duplex Configuration" section in
 38        this document.
 39
 40        For more information about the InterruptThrottleRate,
 41        RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay
 42        parameters, see the application note at:
 43        http://www.intel.com/design/network/applnots/ap450.htm
 44
 45AutoNeg
 46-------
 47(Supported only on adapters with copper connections)
 48Valid Range:   0x01-0x0F, 0x20-0x2F
 49Default Value: 0x2F
 50
 51This parameter is a bit-mask that specifies the speed and duplex settings
 52advertised by the adapter.  When this parameter is used, the Speed and
 53Duplex parameters must not be specified.
 54
 55NOTE:  Refer to the Speed and Duplex section of this readme for more
 56       information on the AutoNeg parameter.
 57
 58Duplex
 59------
 60(Supported only on adapters with copper connections)
 61Valid Range:   0-2 (0=auto-negotiate, 1=half, 2=full)
 62Default Value: 0
 63
 64This defines the direction in which data is allowed to flow.  Can be
 65either one or two-directional.  If both Duplex and the link partner are
 66set to auto-negotiate, the board auto-detects the correct duplex.  If the
 67link partner is forced (either full or half), Duplex defaults to half-
 68duplex.
 69
 70FlowControl
 71-----------
 72Valid Range:   0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx)
 73Default Value: Reads flow control settings from the EEPROM
 74
 75This parameter controls the automatic generation(Tx) and response(Rx)
 76to Ethernet PAUSE frames.
 77
 78InterruptThrottleRate
 79---------------------
 80(not supported on Intel(R) 82542, 82543 or 82544-based adapters)
 81Valid Range:   0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative,
 82                                 4=simplified balancing)
 83Default Value: 3
 84
 85The driver can limit the amount of interrupts per second that the adapter
 86will generate for incoming packets. It does this by writing a value to the
 87adapter that is based on the maximum amount of interrupts that the adapter
 88will generate per second.
 89
 90Setting InterruptThrottleRate to a value greater or equal to 100
 91will program the adapter to send out a maximum of that many interrupts
 92per second, even if more packets have come in. This reduces interrupt
 93load on the system and can lower CPU utilization under heavy load,
 94but will increase latency as packets are not processed as quickly.
 95
 96The default behaviour of the driver previously assumed a static
 97InterruptThrottleRate value of 8000, providing a good fallback value for
 98all traffic types,but lacking in small packet performance and latency.
 99The hardware can handle many more small packets per second however, and
100for this reason an adaptive interrupt moderation algorithm was implemented.
101
102Since 7.3.x, the driver has two adaptive modes (setting 1 or 3) in which
103it dynamically adjusts the InterruptThrottleRate value based on the traffic
104that it receives. After determining the type of incoming traffic in the last
105timeframe, it will adjust the InterruptThrottleRate to an appropriate value
106for that traffic.
107
108The algorithm classifies the incoming traffic every interval into
109classes.  Once the class is determined, the InterruptThrottleRate value is
110adjusted to suit that traffic type the best. There are three classes defined:
111"Bulk traffic", for large amounts of packets of normal size; "Low latency",
112for small amounts of traffic and/or a significant percentage of small
113packets; and "Lowest latency", for almost completely small packets or
114minimal traffic.
115
116In dynamic conservative mode, the InterruptThrottleRate value is set to 4000
117for traffic that falls in class "Bulk traffic". If traffic falls in the "Low
118latency" or "Lowest latency" class, the InterruptThrottleRate is increased
119stepwise to 20000. This default mode is suitable for most applications.
120
121For situations where low latency is vital such as cluster or
122grid computing, the algorithm can reduce latency even more when
123InterruptThrottleRate is set to mode 1. In this mode, which operates
124the same as mode 3, the InterruptThrottleRate will be increased stepwise to
12570000 for traffic in class "Lowest latency".
126
127In simplified mode the interrupt rate is based on the ratio of TX and
128RX traffic.  If the bytes per second rate is approximately equal, the
129interrupt rate will drop as low as 2000 interrupts per second.  If the
130traffic is mostly transmit or mostly receive, the interrupt rate could
131be as high as 8000.
132
133Setting InterruptThrottleRate to 0 turns off any interrupt moderation
134and may improve small packet latency, but is generally not suitable
135for bulk throughput traffic.
136
137NOTE:  InterruptThrottleRate takes precedence over the TxAbsIntDelay and
138       RxAbsIntDelay parameters.  In other words, minimizing the receive
139       and/or transmit absolute delays does not force the controller to
140       generate more interrupts than what the Interrupt Throttle Rate
141       allows.
142
143CAUTION:  If you are using the Intel(R) PRO/1000 CT Network Connection
144          (controller 82547), setting InterruptThrottleRate to a value
145          greater than 75,000, may hang (stop transmitting) adapters
146          under certain network conditions.  If this occurs a NETDEV
147          WATCHDOG message is logged in the system event log.  In
148          addition, the controller is automatically reset, restoring
149          the network connection.  To eliminate the potential for the
150          hang, ensure that InterruptThrottleRate is set no greater
151          than 75,000 and is not set to 0.
152
153NOTE:  When e1000 is loaded with default settings and multiple adapters
154       are in use simultaneously, the CPU utilization may increase non-
155       linearly.  In order to limit the CPU utilization without impacting
156       the overall throughput, we recommend that you load the driver as
157       follows:
158
159           modprobe e1000 InterruptThrottleRate=3000,3000,3000
160
161       This sets the InterruptThrottleRate to 3000 interrupts/sec for
162       the first, second, and third instances of the driver.  The range
163       of 2000 to 3000 interrupts per second works on a majority of
164       systems and is a good starting point, but the optimal value will
165       be platform-specific.  If CPU utilization is not a concern, use
166       RX_POLLING (NAPI) and default driver settings.
167
168RxDescriptors
169-------------
170Valid Range:   80-256 for 82542 and 82543-based adapters
171               80-4096 for all other supported adapters
172Default Value: 256
173
174This value specifies the number of receive buffer descriptors allocated
175by the driver.  Increasing this value allows the driver to buffer more
176incoming packets, at the expense of increased system memory utilization.
177
178Each descriptor is 16 bytes.  A receive buffer is also allocated for each
179descriptor and can be either 2048, 4096, 8192, or 16384 bytes, depending
180on the MTU setting. The maximum MTU size is 16110.
181
182NOTE:  MTU designates the frame size.  It only needs to be set for Jumbo
183       Frames.  Depending on the available system resources, the request
184       for a higher number of receive descriptors may be denied.  In this
185       case, use a lower number.
186
187RxIntDelay
188----------
189Valid Range:   0-65535 (0=off)
190Default Value: 0
191
192This value delays the generation of receive interrupts in units of 1.024
193microseconds.  Receive interrupt reduction can improve CPU efficiency if
194properly tuned for specific network traffic.  Increasing this value adds
195extra latency to frame reception and can end up decreasing the throughput
196of TCP traffic.  If the system is reporting dropped receives, this value
197may be set too high, causing the driver to run out of available receive
198descriptors.
199
200CAUTION:  When setting RxIntDelay to a value other than 0, adapters may
201          hang (stop transmitting) under certain network conditions.  If
202          this occurs a NETDEV WATCHDOG message is logged in the system
203          event log.  In addition, the controller is automatically reset,
204          restoring the network connection.  To eliminate the potential
205          for the hang ensure that RxIntDelay is set to 0.
206
207RxAbsIntDelay
208-------------
209(This parameter is supported only on 82540, 82545 and later adapters.)
210Valid Range:   0-65535 (0=off)
211Default Value: 128
212
213This value, in units of 1.024 microseconds, limits the delay in which a
214receive interrupt is generated.  Useful only if RxIntDelay is non-zero,
215this value ensures that an interrupt is generated after the initial
216packet is received within the set amount of time.  Proper tuning,
217along with RxIntDelay, may improve traffic throughput in specific network
218conditions.
219
220Speed
221-----
222(This parameter is supported only on adapters with copper connections.)
223Valid Settings: 0, 10, 100, 1000
224Default Value:  0 (auto-negotiate at all supported speeds)
225
226Speed forces the line speed to the specified value in megabits per second
227(Mbps).  If this parameter is not specified or is set to 0 and the link
228partner is set to auto-negotiate, the board will auto-detect the correct
229speed.  Duplex should also be set when Speed is set to either 10 or 100.
230
231TxDescriptors
232-------------
233Valid Range:   80-256 for 82542 and 82543-based adapters
234               80-4096 for all other supported adapters
235Default Value: 256
236
237This value is the number of transmit descriptors allocated by the driver.
238Increasing this value allows the driver to queue more transmits.  Each
239descriptor is 16 bytes.
240
241NOTE:  Depending on the available system resources, the request for a
242       higher number of transmit descriptors may be denied.  In this case,
243       use a lower number.
244
245TxDescriptorStep
246----------------
247Valid Range:    1 (use every Tx Descriptor)
248                4 (use every 4th Tx Descriptor)
249
250Default Value:  1 (use every Tx Descriptor)
251
252On certain non-Intel architectures, it has been observed that intense TX
253traffic bursts of short packets may result in an improper descriptor
254writeback. If this occurs, the driver will report a "TX Timeout" and reset
255the adapter, after which the transmit flow will restart, though data may
256have stalled for as much as 10 seconds before it resumes.
257
258The improper writeback does not occur on the first descriptor in a system
259memory cache-line, which is typically 32 bytes, or 4 descriptors long.
260
261Setting TxDescriptorStep to a value of 4 will ensure that all TX descriptors
262are aligned to the start of a system memory cache line, and so this problem
263will not occur.
264
265NOTES: Setting TxDescriptorStep to 4 effectively reduces the number of
266       TxDescriptors available for transmits to 1/4 of the normal allocation.
267       This has a possible negative performance impact, which may be
268       compensated for by allocating more descriptors using the TxDescriptors
269       module parameter.
270
271       There are other conditions which may result in "TX Timeout", which will
272       not be resolved by the use of the TxDescriptorStep parameter. As the
273       issue addressed by this parameter has never been observed on Intel
274       Architecture platforms, it should not be used on Intel platforms.
275
276TxIntDelay
277----------
278Valid Range:   0-65535 (0=off)
279Default Value: 64
280
281This value delays the generation of transmit interrupts in units of
2821.024 microseconds.  Transmit interrupt reduction can improve CPU
283efficiency if properly tuned for specific network traffic.  If the
284system is reporting dropped transmits, this value may be set too high
285causing the driver to run out of available transmit descriptors.
286
287TxAbsIntDelay
288-------------
289(This parameter is supported only on 82540, 82545 and later adapters.)
290Valid Range:   0-65535 (0=off)
291Default Value: 64
292
293This value, in units of 1.024 microseconds, limits the delay in which a
294transmit interrupt is generated.  Useful only if TxIntDelay is non-zero,
295this value ensures that an interrupt is generated after the initial
296packet is sent on the wire within the set amount of time.  Proper tuning,
297along with TxIntDelay, may improve traffic throughput in specific
298network conditions.
299
300XsumRX
301------
302(This parameter is NOT supported on the 82542-based adapter.)
303Valid Range:   0-1
304Default Value: 1
305
306A value of '1' indicates that the driver should enable IP checksum
307offload for received packets (both UDP and TCP) to the adapter hardware.
308
309Copybreak
310---------
311Valid Range:   0-xxxxxxx (0=off)
312Default Value: 256
313Usage: insmod e1000.ko copybreak=128
314
315Driver copies all packets below or equaling this size to a fresh RX
316buffer before handing it up the stack.
317
318This parameter is different than other parameters, in that it is a
319single (not 1,1,1 etc.) parameter applied to all driver instances and
320it is also available during runtime at
321/sys/module/e1000/parameters/copybreak
322
323SmartPowerDownEnable
324--------------------
325Valid Range: 0-1
326Default Value:  0 (disabled)
327
328Allows PHY to turn off in lower power states. The user can turn off
329this parameter in supported chipsets.
330
331KumeranLockLoss
332---------------
333Valid Range: 0-1
334Default Value: 1 (enabled)
335
336This workaround skips resetting the PHY at shutdown for the initial
337silicon releases of ICH8 systems.
338
339Speed and Duplex Configuration
340==============================
341
342Three keywords are used to control the speed and duplex configuration.
343These keywords are Speed, Duplex, and AutoNeg.
344
345If the board uses a fiber interface, these keywords are ignored, and the
346fiber interface board only links at 1000 Mbps full-duplex.
347
348For copper-based boards, the keywords interact as follows:
349
350  The default operation is auto-negotiate.  The board advertises all
351  supported speed and duplex combinations, and it links at the highest
352  common speed and duplex mode IF the link partner is set to auto-negotiate.
353
354  If Speed = 1000, limited auto-negotiation is enabled and only 1000 Mbps
355  is advertised (The 1000BaseT spec requires auto-negotiation.)
356
357  If Speed = 10 or 100, then both Speed and Duplex should be set.  Auto-
358  negotiation is disabled, and the AutoNeg parameter is ignored.  Partner
359  SHOULD also be forced.
360
361The AutoNeg parameter is used when more control is required over the
362auto-negotiation process.  It should be used when you wish to control which
363speed and duplex combinations are advertised during the auto-negotiation
364process.
365
366The parameter may be specified as either a decimal or hexadecimal value as
367determined by the bitmap below.
368
369Bit position   7      6      5       4       3      2      1       0
370Decimal Value  128    64     32      16      8      4      2       1
371Hex value      80     40     20      10      8      4      2       1
372Speed (Mbps)   N/A    N/A    1000    N/A     100    100    10      10
373Duplex                       Full            Full   Half   Full    Half
374
375Some examples of using AutoNeg:
376
377  modprobe e1000 AutoNeg=0x01 (Restricts autonegotiation to 10 Half)
378  modprobe e1000 AutoNeg=1 (Same as above)
379  modprobe e1000 AutoNeg=0x02 (Restricts autonegotiation to 10 Full)
380  modprobe e1000 AutoNeg=0x03 (Restricts autonegotiation to 10 Half or 10 Full)
381  modprobe e1000 AutoNeg=0x04 (Restricts autonegotiation to 100 Half)
382  modprobe e1000 AutoNeg=0x05 (Restricts autonegotiation to 10 Half or 100
383  Half)
384  modprobe e1000 AutoNeg=0x020 (Restricts autonegotiation to 1000 Full)
385  modprobe e1000 AutoNeg=32 (Same as above)
386
387Note that when this parameter is used, Speed and Duplex must not be specified.
388
389If the link partner is forced to a specific speed and duplex, then this
390parameter should not be used.  Instead, use the Speed and Duplex parameters
391previously mentioned to force the adapter to the same speed and duplex.
392
393Additional Configurations
394=========================
395
396  Jumbo Frames
397  ------------
398  Jumbo Frames support is enabled by changing the MTU to a value larger than
399  the default of 1500.  Use the ifconfig command to increase the MTU size.
400  For example:
401
402       ifconfig eth<x> mtu 9000 up
403
404  This setting is not saved across reboots.  It can be made permanent if
405  you add:
406
407       MTU=9000
408
409   to the file /etc/sysconfig/network-scripts/ifcfg-eth<x>.  This example
410   applies to the Red Hat distributions; other distributions may store this
411   setting in a different location.
412
413  Notes:
414  Degradation in throughput performance may be observed in some Jumbo frames
415  environments. If this is observed, increasing the application's socket buffer
416  size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values may help.
417  See the specific application manual and /usr/src/linux*/Documentation/
418  networking/ip-sysctl.txt for more details.
419
420  - The maximum MTU setting for Jumbo Frames is 16110.  This value coincides
421    with the maximum Jumbo Frames size of 16128.
422
423  - Using Jumbo frames at 10 or 100 Mbps is not supported and may result in
424    poor performance or loss of link.
425
426  - Adapters based on the Intel(R) 82542 and 82573V/E controller do not
427    support Jumbo Frames. These correspond to the following product names:
428     Intel(R) PRO/1000 Gigabit Server Adapter
429     Intel(R) PRO/1000 PM Network Connection
430
431  ethtool
432  -------
433  The driver utilizes the ethtool interface for driver configuration and
434  diagnostics, as well as displaying statistical information.  The ethtool
435  version 1.6 or later is required for this functionality.
436
437  The latest release of ethtool can be found from
438  http://ftp.kernel.org/pub/software/network/ethtool/
439
440  Enabling Wake on LAN* (WoL)
441  ---------------------------
442  WoL is configured through the ethtool* utility.
443
444  WoL will be enabled on the system during the next shut down or reboot.
445  For this driver version, in order to enable WoL, the e1000 driver must be
446  loaded when shutting down or rebooting the system.
447
448Support
449=======
450
451For general information, go to the Intel support website at:
452
453    http://support.intel.com
454
455or the Intel Wired Networking project hosted by Sourceforge at:
456
457    http://sourceforge.net/projects/e1000
458
459If an issue is identified with the released source code on the supported
460kernel with a supported adapter, email the specific information related
461to the issue to e1000-devel@lists.sf.net