8
The Intelligent Platform Management Interface, or IPMI, is a
9
standard for controlling intelligent devices that monitor a system.
10
It provides for dynamic discovery of sensors in the system and the
11
ability to monitor the sensors and be informed when the sensor's
12
values change or go outside certain boundaries. It also has a
13
standardized database for field-replaceable units (FRUs) and a watchdog
16
To use this, you need an interface to an IPMI controller in your
17
system (called a Baseboard Management Controller, or BMC) and
18
management software that can use the IPMI system.
20
This document describes how to use the IPMI driver for Linux. If you
21
are not familiar with IPMI itself, see the web site at
22
http://www.intel.com/design/servers/ipmi/index.htm. IPMI is a big
23
subject and I can't cover it all here!
28
The Linux IPMI driver is modular, which means you have to pick several
29
things to have it work right depending on your hardware. Most of
30
these are available in the 'Character Devices' menu then the IPMI
33
No matter what, you must pick 'IPMI top-level message handler' to use
34
IPMI. What you do beyond that depends on your needs and hardware.
36
The message handler does not provide any user-level interfaces.
37
Kernel code (like the watchdog) can still use it. If you need access
38
from userland, you need to select 'Device interface for IPMI' if you
39
want access through a device driver.
41
The driver interface depends on your hardware. If your system
42
properly provides the SMBIOS info for IPMI, the driver will detect it
43
and just work. If you have a board with a standard interface (These
44
will generally be either "KCS", "SMIC", or "BT", consult your hardware
45
manual), choose the 'IPMI SI handler' option. A driver also exists
46
for direct I2C access to the IPMI management controller. Some boards
47
support this, but it is unknown if it will work on every board. For
48
this, choose 'IPMI SMBus handler', but be ready to try to do some
49
figuring to see if it will work on your system if the SMBIOS/APCI
50
information is wrong or not present. It is fairly safe to have both
51
these enabled and let the drivers auto-detect what is present.
53
You should generally enable ACPI on your system, as systems with IPMI
54
can have ACPI tables describing them.
56
If you have a standard interface and the board manufacturer has done
57
their job correctly, the IPMI controller should be automatically
58
detected (via ACPI or SMBIOS tables) and should just work. Sadly,
59
many boards do not have this information. The driver attempts
60
standard defaults, but they may not work. If you fall into this
61
situation, you need to read the section below named 'The SI Driver' or
62
"The SMBus Driver" on how to hand-configure your system.
64
IPMI defines a standard watchdog timer. You can enable this with the
65
'IPMI Watchdog Timer' config option. If you compile the driver into
66
the kernel, then via a kernel command-line option you can have the
67
watchdog timer start as soon as it initializes. It also have a lot
68
of other options, see the 'Watchdog' section below for more details.
69
Note that you can also have the watchdog continue to run if it is
70
closed (by default it is disabled on close). Go into the 'Watchdog
71
Cards' menu, enable 'Watchdog Timer Support', and enable the option
72
'Disable watchdog shutdown on close'.
74
IPMI systems can often be powered off using IPMI commands. Select
75
'IPMI Poweroff' to do this. The driver will auto-detect if the system
76
can be powered off by IPMI. It is safe to enable this even if your
77
system doesn't support this option. This works on ATCA systems, the
78
Radisys CPI1 card, and any IPMI system that supports standard chassis
81
If you want the driver to put an event into the event log on a panic,
82
enable the 'Generate a panic event to all BMCs on a panic' option. If
83
you want the whole panic string put into the event log using OEM
84
events, enable the 'Generate OEM events containing the panic string'
90
The Linux IPMI driver is designed to be very modular and flexible, you
91
only need to take the pieces you need and you can use it in many
92
different ways. Because of that, it's broken into many chunks of
93
code. These chunks (by module name) are:
95
ipmi_msghandler - This is the central piece of software for the IPMI
96
system. It handles all messages, message timing, and responses. The
97
IPMI users tie into this, and the IPMI physical interfaces (called
98
System Management Interfaces, or SMIs) also tie in here. This
99
provides the kernelland interface for IPMI, but does not provide an
100
interface for use by application processes.
102
ipmi_devintf - This provides a userland IOCTL interface for the IPMI
103
driver, each open file for this device ties in to the message handler
106
ipmi_si - A driver for various system interfaces. This supports KCS,
107
SMIC, and BT interfaces. Unless you have an SMBus interface or your
108
own custom interface, you probably need to use this.
110
ipmi_smb - A driver for accessing BMCs on the SMBus. It uses the
111
I2C kernel driver's SMBus interfaces to send and receive IPMI messages
114
ipmi_watchdog - IPMI requires systems to have a very capable watchdog
115
timer. This driver implements the standard Linux watchdog timer
116
interface on top of the IPMI message handler.
118
ipmi_poweroff - Some systems support the ability to be turned off via
121
These are all individually selectable via configuration options.
123
Note that the KCS-only interface has been removed. The af_ipmi driver
124
is no longer supported and has been removed because it was impossible
125
to do 32 bit emulation on 64-bit kernels with it.
127
Much documentation for the interface is in the include files. The
128
IPMI include files are:
130
net/af_ipmi.h - Contains the socket interface.
132
linux/ipmi.h - Contains the user interface and IOCTL interface for IPMI.
134
linux/ipmi_smi.h - Contains the interface for system management interfaces
135
(things that interface to IPMI controllers) to use.
137
linux/ipmi_msgdefs.h - General definitions for base IPMI messaging.
143
The IPMI addressing works much like IP addresses, you have an overlay
144
to handle the different address types. The overlay is:
150
char data[IPMI_MAX_ADDR_SIZE];
153
The addr_type determines what the address really is. The driver
154
currently understands two different types of addresses.
156
"System Interface" addresses are defined as:
158
struct ipmi_system_interface_addr
164
and the type is IPMI_SYSTEM_INTERFACE_ADDR_TYPE. This is used for talking
165
straight to the BMC on the current card. The channel must be
168
Messages that are destined to go out on the IPMB bus use the
169
IPMI_IPMB_ADDR_TYPE address type. The format is
171
struct ipmi_ipmb_addr
175
unsigned char slave_addr;
179
The "channel" here is generally zero, but some devices support more
180
than one channel, it corresponds to the channel as defined in the IPMI
187
Messages are defined as:
198
The driver takes care of adding/stripping the header information. The
199
data portion is just the data to be send (do NOT put addressing info
200
here) or the response. Note that the completion code of a response is
201
the first item in "data", it is not stripped out because that is how
202
all the messages are defined in the spec (and thus makes counting the
203
offsets a little easier :-).
205
When using the IOCTL interface from userland, you must provide a block
206
of data for "data", fill it, and set data_len to the length of the
207
block of data, even when receiving messages. Otherwise the driver
208
will have no place to put the message.
210
Messages coming up from the message handler in kernelland will come in
215
struct list_head link;
217
/* The type of message as defined in the "Receive Types"
222
struct ipmi_addr addr;
226
/* Call this when done with the message. It will presumably free
227
the message and do any other necessary cleanup. */
228
void (*done)(struct ipmi_recv_msg *msg);
230
/* Place-holder for the data, don't make any assumptions about
231
the size or existence of this, since it may change. */
232
unsigned char msg_data[IPMI_MAX_MSG_LENGTH];
235
You should look at the receive type and handle the message
239
The Upper Layer Interface (Message Handler)
240
-------------------------------------------
242
The upper layer of the interface provides the users with a consistent
243
view of the IPMI interfaces. It allows multiple SMI interfaces to be
244
addressed (because some boards actually have multiple BMCs on them)
245
and the user should not have to care what type of SMI is below them.
250
To user the message handler, you must first create a user using
251
ipmi_create_user. The interface number specifies which SMI you want
252
to connect to, and you must supply callback functions to be called
253
when data comes in. The callback function can run at interrupt level,
254
so be careful using the callbacks. This also allows to you pass in a
255
piece of data, the handler_data, that will be passed back to you on
258
Once you are done, call ipmi_destroy_user() to get rid of the user.
260
From userland, opening the device automatically creates a user, and
261
closing the device automatically destroys the user.
266
To send a message from kernel-land, the ipmi_request() call does
267
pretty much all message handling. Most of the parameter are
268
self-explanatory. However, it takes a "msgid" parameter. This is NOT
269
the sequence number of messages. It is simply a long value that is
270
passed back when the response for the message is returned. You may
271
use it for anything you like.
273
Responses come back in the function pointed to by the ipmi_recv_hndl
274
field of the "handler" that you passed in to ipmi_create_user().
275
Remember again, these may be running at interrupt level. Remember to
276
look at the receive type, too.
278
From userland, you fill out an ipmi_req_t structure and use the
279
IPMICTL_SEND_COMMAND ioctl. For incoming stuff, you can use select()
280
or poll() to wait for messages to come in. However, you cannot use
281
read() to get them, you must call the IPMICTL_RECEIVE_MSG with the
282
ipmi_recv_t structure to actually get the message. Remember that you
283
must supply a pointer to a block of data in the msg.data field, and
284
you must fill in the msg.data_len field with the size of the data.
285
This gives the receiver a place to actually put the message.
287
If the message cannot fit into the data you provide, you will get an
288
EMSGSIZE error and the driver will leave the data in the receive
289
queue. If you want to get it and have it truncate the message, us
290
the IPMICTL_RECEIVE_MSG_TRUNC ioctl.
292
When you send a command (which is defined by the lowest-order bit of
293
the netfn per the IPMI spec) on the IPMB bus, the driver will
294
automatically assign the sequence number to the command and save the
295
command. If the response is not receive in the IPMI-specified 5
296
seconds, it will generate a response automatically saying the command
297
timed out. If an unsolicited response comes in (if it was after 5
298
seconds, for instance), that response will be ignored.
300
In kernelland, after you receive a message and are done with it, you
301
MUST call ipmi_free_recv_msg() on it, or you will leak messages. Note
302
that you should NEVER mess with the "done" field of a message, that is
303
required to properly clean up the message.
305
Note that when sending, there is an ipmi_request_supply_msgs() call
306
that lets you supply the smi and receive message. This is useful for
307
pieces of code that need to work even if the system is out of buffers
308
(the watchdog timer uses this, for instance). You supply your own
309
buffer and own free routines. This is not recommended for normal use,
310
though, since it is tricky to manage your own buffers.
313
Events and Incoming Commands
315
The driver takes care of polling for IPMI events and receiving
316
commands (commands are messages that are not responses, they are
317
commands that other things on the IPMB bus have sent you). To receive
318
these, you must register for them, they will not automatically be sent
321
To receive events, you must call ipmi_set_gets_events() and set the
322
"val" to non-zero. Any events that have been received by the driver
323
since startup will immediately be delivered to the first user that
324
registers for events. After that, if multiple users are registered
325
for events, they will all receive all events that come in.
327
For receiving commands, you have to individually register commands you
328
want to receive. Call ipmi_register_for_cmd() and supply the netfn
329
and command name for each command you want to receive. You also
330
specify a bitmask of the channels you want to receive the command from
331
(or use IPMI_CHAN_ALL for all channels if you don't care). Only one
332
user may be registered for each netfn/cmd/channel, but different users
333
may register for different commands, or the same command if the
334
channel bitmasks do not overlap.
336
From userland, equivalent IOCTLs are provided to do these functions.
339
The Lower Layer (SMI) Interface
340
-------------------------------
342
As mentioned before, multiple SMI interfaces may be registered to the
343
message handler, each of these is assigned an interface number when
344
they register with the message handler. They are generally assigned
345
in the order they register, although if an SMI unregisters and then
346
another one registers, all bets are off.
348
The ipmi_smi.h defines the interface for management interfaces, see
349
that for more details.
355
The SI driver allows up to 4 KCS or SMIC interfaces to be configured
356
in the system. By default, scan the ACPI tables for interfaces, and
357
if it doesn't find any the driver will attempt to register one KCS
358
interface at the spec-specified I/O port 0xca2 without interrupts.
359
You can change this at module load time (for a module) with:
361
modprobe ipmi_si.o type=<type1>,<type2>....
362
ports=<port1>,<port2>... addrs=<addr1>,<addr2>...
363
irqs=<irq1>,<irq2>... trydefaults=[0|1]
364
regspacings=<sp1>,<sp2>,... regsizes=<size1>,<size2>,...
365
regshifts=<shift1>,<shift2>,...
366
slave_addrs=<addr1>,<addr2>,...
367
force_kipmid=<enable1>,<enable2>,...
368
kipmid_max_busy_us=<ustime1>,<ustime2>,...
369
unload_when_empty=[0|1]
371
Each of these except si_trydefaults is a list, the first item for the
372
first interface, second item for the second interface, etc.
374
The si_type may be either "kcs", "smic", or "bt". If you leave it blank, it
377
If you specify si_addrs as non-zero for an interface, the driver will
378
use the memory address given as the address of the device. This
381
If you specify si_ports as non-zero for an interface, the driver will
382
use the I/O port given as the device address.
384
If you specify si_irqs as non-zero for an interface, the driver will
385
attempt to use the given interrupt for the device.
387
si_trydefaults sets whether the standard IPMI interface at 0xca2 and
388
any interfaces specified by ACPE are tried. By default, the driver
389
tries it, set this value to zero to turn this off.
391
The next three parameters have to do with register layout. The
392
registers used by the interfaces may not appear at successive
393
locations and they may not be in 8-bit registers. These parameters
394
allow the layout of the data in the registers to be more precisely
397
The regspacings parameter give the number of bytes between successive
398
register start addresses. For instance, if the regspacing is set to 4
399
and the start address is 0xca2, then the address for the second
400
register would be 0xca6. This defaults to 1.
402
The regsizes parameter gives the size of a register, in bytes. The
403
data used by IPMI is 8-bits wide, but it may be inside a larger
404
register. This parameter allows the read and write type to specified.
405
It may be 1, 2, 4, or 8. The default is 1.
407
Since the register size may be larger than 32 bits, the IPMI data may not
408
be in the lower 8 bits. The regshifts parameter give the amount to shift
409
the data to get to the actual IPMI data.
411
The slave_addrs specifies the IPMI address of the local BMC. This is
412
usually 0x20 and the driver defaults to that, but in case it's not, it
413
can be specified when the driver starts up.
415
The force_ipmid parameter forcefully enables (if set to 1) or disables
416
(if set to 0) the kernel IPMI daemon. Normally this is auto-detected
417
by the driver, but systems with broken interrupts might need an enable,
418
or users that don't want the daemon (don't need the performance, don't
419
want the CPU hit) can disable it.
421
If unload_when_empty is set to 1, the driver will be unloaded if it
422
doesn't find any interfaces or all the interfaces fail to work. The
423
default is one. Setting to 0 is useful with the hotmod, but is
424
obviously only useful for modules.
426
When compiled into the kernel, the parameters can be specified on the
427
kernel command line as:
429
ipmi_si.type=<type1>,<type2>...
430
ipmi_si.ports=<port1>,<port2>... ipmi_si.addrs=<addr1>,<addr2>...
431
ipmi_si.irqs=<irq1>,<irq2>... ipmi_si.trydefaults=[0|1]
432
ipmi_si.regspacings=<sp1>,<sp2>,...
433
ipmi_si.regsizes=<size1>,<size2>,...
434
ipmi_si.regshifts=<shift1>,<shift2>,...
435
ipmi_si.slave_addrs=<addr1>,<addr2>,...
436
ipmi_si.force_kipmid=<enable1>,<enable2>,...
437
ipmi_si.kipmid_max_busy_us=<ustime1>,<ustime2>,...
439
It works the same as the module parameters of the same names.
441
By default, the driver will attempt to detect any device specified by
442
ACPI, and if none of those then a KCS device at the spec-specified
443
0xca2. If you want to turn this off, set the "trydefaults" option to
446
If your IPMI interface does not support interrupts and is a KCS or
447
SMIC interface, the IPMI driver will start a kernel thread for the
448
interface to help speed things up. This is a low-priority kernel
449
thread that constantly polls the IPMI driver while an IPMI operation
450
is in progress. The force_kipmid module parameter will all the user to
451
force this thread on or off. If you force it off and don't have
452
interrupts, the driver will run VERY slowly. Don't blame me,
453
these interfaces suck.
455
Unfortunately, this thread can use a lot of CPU depending on the
456
interface's performance. This can waste a lot of CPU and cause
457
various issues with detecting idle CPU and using extra power. To
458
avoid this, the kipmid_max_busy_us sets the maximum amount of time, in
459
microseconds, that kipmid will spin before sleeping for a tick. This
460
value sets a balance between performance and CPU waste and needs to be
461
tuned to your needs. Maybe, someday, auto-tuning will be added, but
462
that's not a simple thing and even the auto-tuning would need to be
463
tuned to the user's desired performance.
465
The driver supports a hot add and remove of interfaces. This way,
466
interfaces can be added or removed after the kernel is up and running.
467
This is done using /sys/modules/ipmi_si/parameters/hotmod, which is a
468
write-only parameter. You write a string to this interface. The string
472
add|remove,kcs|bt|smic,mem|i/o,<address>[,<opt1>[,<opt2>[,...]]]
473
You can specify more than one interface on the line. The "opt"s are:
478
ipmb=<ipmb slave addr>
479
and these have the same meanings as discussed above. Note that you
480
can also use this on the kernel command line for a more compact format
481
for specifying an interface. Note that when removing an interface,
482
only the first three parameters (si type, address type, and address)
483
are used for the comparison. Any options are ignored for removing.
488
The SMBus driver allows up to 4 SMBus devices to be configured in the
489
system. By default, the driver will register any SMBus interfaces it finds
490
in the I2C address range of 0x20 to 0x4f on any adapter. You can change this
491
at module load time (for a module) with:
494
addr=<adapter1>,<i2caddr1>[,<adapter2>,<i2caddr2>[,...]]
495
dbg=<flags1>,<flags2>...
496
[defaultprobe=1] [dbg_probe=1]
498
The addresses are specified in pairs, the first is the adapter ID and the
499
second is the I2C address on that adapter.
501
The debug flags are bit flags for each BMC found, they are:
502
IPMI messages: 1, driver state: 2, timing: 4, I2C probe: 8
504
Setting smb_defaultprobe to zero disabled the default probing of SMBus
505
interfaces at address range 0x20 to 0x4f. This means that only the
506
BMCs specified on the smb_addr line will be detected.
508
Setting smb_dbg_probe to 1 will enable debugging of the probing and
509
detection process for BMCs on the SMBusses.
511
Discovering the IPMI compliant BMC on the SMBus can cause devices
512
on the I2C bus to fail. The SMBus driver writes a "Get Device ID" IPMI
513
message as a block write to the I2C bus and waits for a response.
514
This action can be detrimental to some I2C devices. It is highly recommended
515
that the known I2c address be given to the SMBus driver in the smb_addr
516
parameter. The default address range will not be used when a smb_addr
517
parameter is provided.
519
When compiled into the kernel, the addresses can be specified on the
520
kernel command line as:
522
ipmb_smb.addr=<adapter1>,<i2caddr1>[,<adapter2>,<i2caddr2>[,...]]
523
ipmi_smb.dbg=<flags1>,<flags2>...
524
ipmi_smb.defaultprobe=0 ipmi_smb.dbg_probe=1
526
These are the same options as on the module command line.
528
Note that you might need some I2C changes if CONFIG_IPMI_PANIC_EVENT
529
is enabled along with this, so the I2C driver knows to run to
530
completion during sending a panic event.
536
Get the detailed info related with the IPMI device
537
--------------------------------------------------
539
Some users need more detailed information about a device, like where
540
the address came from or the raw base device for the IPMI interface.
541
You can use the IPMI smi_watcher to catch the IPMI interfaces as they
542
come or go, and to grab the information, you can use the function
543
ipmi_get_smi_info(), which returns the following structure:
545
struct ipmi_smi_info {
546
enum ipmi_addr_src addr_src;
555
Currently special info for only for SI_ACPI address sources is
556
returned. Others may be added as necessary.
558
Note that the dev pointer is included in the above structure, and
559
assuming ipmi_smi_get_info returns success, you must call put_device
566
A watchdog timer is provided that implements the Linux-standard
567
watchdog timer interface. It has three module parameters that can be
570
modprobe ipmi_watchdog timeout=<t> pretimeout=<t> action=<action type>
571
preaction=<preaction type> preop=<preop type> start_now=x
572
nowayout=x ifnum_to_use=n
574
ifnum_to_use specifies which interface the watchdog timer should use.
575
The default is -1, which means to pick the first one registered.
577
The timeout is the number of seconds to the action, and the pretimeout
578
is the amount of seconds before the reset that the pre-timeout panic will
579
occur (if pretimeout is zero, then pretimeout will not be enabled). Note
580
that the pretimeout is the time before the final timeout. So if the
581
timeout is 50 seconds and the pretimeout is 10 seconds, then the pretimeout
582
will occur in 40 second (10 seconds before the timeout).
584
The action may be "reset", "power_cycle", or "power_off", and
585
specifies what to do when the timer times out, and defaults to
588
The preaction may be "pre_smi" for an indication through the SMI
589
interface, "pre_int" for an indication through the SMI with an
590
interrupts, and "pre_nmi" for a NMI on a preaction. This is how
591
the driver is informed of the pretimeout.
593
The preop may be set to "preop_none" for no operation on a pretimeout,
594
"preop_panic" to set the preoperation to panic, or "preop_give_data"
595
to provide data to read from the watchdog device when the pretimeout
596
occurs. A "pre_nmi" setting CANNOT be used with "preop_give_data"
597
because you can't do data operations from an NMI.
599
When preop is set to "preop_give_data", one byte comes ready to read
600
on the device when the pretimeout occurs. Select and fasync work on
603
If start_now is set to 1, the watchdog timer will start running as
604
soon as the driver is loaded.
606
If nowayout is set to 1, the watchdog timer will not stop when the
607
watchdog device is closed. The default value of nowayout is true
608
if the CONFIG_WATCHDOG_NOWAYOUT option is enabled, or false if not.
610
When compiled into the kernel, the kernel command line is available
611
for configuring the watchdog:
613
ipmi_watchdog.timeout=<t> ipmi_watchdog.pretimeout=<t>
614
ipmi_watchdog.action=<action type>
615
ipmi_watchdog.preaction=<preaction type>
616
ipmi_watchdog.preop=<preop type>
617
ipmi_watchdog.start_now=x
618
ipmi_watchdog.nowayout=x
620
The options are the same as the module parameter options.
622
The watchdog will panic and start a 120 second reset timeout if it
623
gets a pre-action. During a panic or a reboot, the watchdog will
624
start a 120 timer if it is running to make sure the reboot occurs.
626
Note that if you use the NMI preaction for the watchdog, you MUST NOT
627
use the nmi watchdog. There is no reasonable way to tell if an NMI
628
comes from the IPMI controller, so it must assume that if it gets an
629
otherwise unhandled NMI, it must be from IPMI and it will panic
632
Once you open the watchdog timer, you must write a 'V' character to the
633
device to close it, or the timer will not stop. This is a new semantic
634
for the driver, but makes it consistent with the rest of the watchdog
641
The OpenIPMI driver supports the ability to put semi-custom and custom
642
events in the system event log if a panic occurs. if you enable the
643
'Generate a panic event to all BMCs on a panic' option, you will get
644
one event on a panic in a standard IPMI event format. If you enable
645
the 'Generate OEM events containing the panic string' option, you will
646
also get a bunch of OEM events holding the panic string.
649
The field settings of the events are:
650
* Generator ID: 0x21 (kernel)
651
* EvM Rev: 0x03 (this event is formatting in IPMI 1.0 format)
652
* Sensor Type: 0x20 (OS critical stop sensor)
653
* Sensor #: The first byte of the panic string (0 if no panic string)
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* Event Dir | Event Type: 0x6f (Assertion, sensor-specific event info)
655
* Event Data 1: 0xa1 (Runtime stop in OEM bytes 2 and 3)
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* Event data 2: second byte of panic string
657
* Event data 3: third byte of panic string
658
See the IPMI spec for the details of the event layout. This event is
659
always sent to the local management controller. It will handle routing
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the message to the right place
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Other OEM events have the following format:
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Record ID (bytes 0-1): Set by the SEL.
664
Record type (byte 2): 0xf0 (OEM non-timestamped)
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byte 3: The slave address of the card saving the panic
666
byte 4: A sequence number (starting at zero)
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The rest of the bytes (11 bytes) are the panic string. If the panic string
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is longer than 11 bytes, multiple messages will be sent with increasing
671
Because you cannot send OEM events using the standard interface, this
672
function will attempt to find an SEL and add the events there. It
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will first query the capabilities of the local management controller.
674
If it has an SEL, then they will be stored in the SEL of the local
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management controller. If not, and the local management controller is
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an event generator, the event receiver from the local management
677
controller will be queried and the events sent to the SEL on that
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device. Otherwise, the events go nowhere since there is nowhere to
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If the poweroff capability is selected, the IPMI driver will install
686
a shutdown function into the standard poweroff function pointer. This
687
is in the ipmi_poweroff module. When the system requests a powerdown,
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it will send the proper IPMI commands to do this. This is supported on
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There is a module parameter named "poweroff_powercycle" that may
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either be zero (do a power down) or non-zero (do a power cycle, power
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the system off, then power it on in a few seconds). Setting
694
ipmi_poweroff.poweroff_control=x will do the same thing on the kernel
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command line. The parameter is also available via the proc filesystem
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in /proc/sys/dev/ipmi/poweroff_powercycle. Note that if the system
697
does not support power cycling, it will always do the power off.
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The "ifnum_to_use" parameter specifies which interface the poweroff
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code should use. The default is -1, which means to pick the first one
703
Note that if you have ACPI enabled, the system will prefer using ACPI to