blob: 16eb4c9e92330fe62214b3f6af5944c7bb92591e [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001
2 The Linux IPMI Driver
3 ---------------------
4 Corey Minyard
5 <minyard@mvista.com>
6 <minyard@acm.org>
7
8The Intelligent Platform Management Interface, or IPMI, is a
9standard for controlling intelligent devices that monitor a system.
10It provides for dynamic discovery of sensors in the system and the
11ability to monitor the sensors and be informed when the sensor's
12values change or go outside certain boundaries. It also has a
Matt LaPlantedc474c82006-06-30 01:56:06 -070013standardized database for field-replaceable units (FRUs) and a watchdog
Linus Torvalds1da177e2005-04-16 15:20:36 -070014timer.
15
16To use this, you need an interface to an IPMI controller in your
17system (called a Baseboard Management Controller, or BMC) and
18management software that can use the IPMI system.
19
20This document describes how to use the IPMI driver for Linux. If you
21are not familiar with IPMI itself, see the web site at
22http://www.intel.com/design/servers/ipmi/index.htm. IPMI is a big
23subject and I can't cover it all here!
24
25Configuration
26-------------
27
Corey Minyard845e78a2005-06-23 22:01:39 -070028The Linux IPMI driver is modular, which means you have to pick several
Linus Torvalds1da177e2005-04-16 15:20:36 -070029things to have it work right depending on your hardware. Most of
Corey Minyard845e78a2005-06-23 22:01:39 -070030these are available in the 'Character Devices' menu then the IPMI
31menu.
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33No matter what, you must pick 'IPMI top-level message handler' to use
34IPMI. What you do beyond that depends on your needs and hardware.
35
36The message handler does not provide any user-level interfaces.
37Kernel code (like the watchdog) can still use it. If you need access
38from userland, you need to select 'Device interface for IPMI' if you
Corey Minyard845e78a2005-06-23 22:01:39 -070039want access through a device driver.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
Corey Minyard845e78a2005-06-23 22:01:39 -070041The driver interface depends on your hardware. If your system
42properly provides the SMBIOS info for IPMI, the driver will detect it
43and just work. If you have a board with a standard interface (These
44will generally be either "KCS", "SMIC", or "BT", consult your hardware
Corey Minyardd1bdc402012-10-16 15:53:36 -050045manual), choose the 'IPMI SI handler' option.
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
47You should generally enable ACPI on your system, as systems with IPMI
Corey Minyard845e78a2005-06-23 22:01:39 -070048can have ACPI tables describing them.
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50If you have a standard interface and the board manufacturer has done
51their job correctly, the IPMI controller should be automatically
Corey Minyard845e78a2005-06-23 22:01:39 -070052detected (via ACPI or SMBIOS tables) and should just work. Sadly,
53many boards do not have this information. The driver attempts
54standard defaults, but they may not work. If you fall into this
Corey Minyardd1bdc402012-10-16 15:53:36 -050055situation, you need to read the section below named 'The SI Driver'.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
57IPMI defines a standard watchdog timer. You can enable this with the
58'IPMI Watchdog Timer' config option. If you compile the driver into
59the kernel, then via a kernel command-line option you can have the
Matt LaPlantedc474c82006-06-30 01:56:06 -070060watchdog timer start as soon as it initializes. It also have a lot
Linus Torvalds1da177e2005-04-16 15:20:36 -070061of other options, see the 'Watchdog' section below for more details.
62Note that you can also have the watchdog continue to run if it is
63closed (by default it is disabled on close). Go into the 'Watchdog
64Cards' menu, enable 'Watchdog Timer Support', and enable the option
65'Disable watchdog shutdown on close'.
66
Corey Minyard845e78a2005-06-23 22:01:39 -070067IPMI systems can often be powered off using IPMI commands. Select
68'IPMI Poweroff' to do this. The driver will auto-detect if the system
69can be powered off by IPMI. It is safe to enable this even if your
70system doesn't support this option. This works on ATCA systems, the
71Radisys CPI1 card, and any IPMI system that supports standard chassis
72management commands.
73
74If you want the driver to put an event into the event log on a panic,
75enable the 'Generate a panic event to all BMCs on a panic' option. If
76you want the whole panic string put into the event log using OEM
77events, enable the 'Generate OEM events containing the panic string'
78option.
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
80Basic Design
81------------
82
83The Linux IPMI driver is designed to be very modular and flexible, you
84only need to take the pieces you need and you can use it in many
85different ways. Because of that, it's broken into many chunks of
Corey Minyard845e78a2005-06-23 22:01:39 -070086code. These chunks (by module name) are:
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
88ipmi_msghandler - This is the central piece of software for the IPMI
89system. It handles all messages, message timing, and responses. The
90IPMI users tie into this, and the IPMI physical interfaces (called
91System Management Interfaces, or SMIs) also tie in here. This
92provides the kernelland interface for IPMI, but does not provide an
93interface for use by application processes.
94
95ipmi_devintf - This provides a userland IOCTL interface for the IPMI
96driver, each open file for this device ties in to the message handler
97as an IPMI user.
98
Corey Minyard845e78a2005-06-23 22:01:39 -070099ipmi_si - A driver for various system interfaces. This supports KCS,
Corey Minyardd1bdc402012-10-16 15:53:36 -0500100SMIC, and BT interfaces.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101
Corey Minyard845e78a2005-06-23 22:01:39 -0700102ipmi_watchdog - IPMI requires systems to have a very capable watchdog
103timer. This driver implements the standard Linux watchdog timer
104interface on top of the IPMI message handler.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
Corey Minyard845e78a2005-06-23 22:01:39 -0700106ipmi_poweroff - Some systems support the ability to be turned off via
107IPMI commands.
108
109These are all individually selectable via configuration options.
110
111Note that the KCS-only interface has been removed. The af_ipmi driver
112is no longer supported and has been removed because it was impossible
113to do 32 bit emulation on 64-bit kernels with it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114
115Much documentation for the interface is in the include files. The
116IPMI include files are:
117
118net/af_ipmi.h - Contains the socket interface.
119
120linux/ipmi.h - Contains the user interface and IOCTL interface for IPMI.
121
122linux/ipmi_smi.h - Contains the interface for system management interfaces
123(things that interface to IPMI controllers) to use.
124
125linux/ipmi_msgdefs.h - General definitions for base IPMI messaging.
126
127
128Addressing
129----------
130
131The IPMI addressing works much like IP addresses, you have an overlay
132to handle the different address types. The overlay is:
133
134 struct ipmi_addr
135 {
136 int addr_type;
137 short channel;
138 char data[IPMI_MAX_ADDR_SIZE];
139 };
140
141The addr_type determines what the address really is. The driver
142currently understands two different types of addresses.
143
144"System Interface" addresses are defined as:
145
146 struct ipmi_system_interface_addr
147 {
148 int addr_type;
149 short channel;
150 };
151
152and the type is IPMI_SYSTEM_INTERFACE_ADDR_TYPE. This is used for talking
153straight to the BMC on the current card. The channel must be
154IPMI_BMC_CHANNEL.
155
156Messages that are destined to go out on the IPMB bus use the
157IPMI_IPMB_ADDR_TYPE address type. The format is
158
159 struct ipmi_ipmb_addr
160 {
161 int addr_type;
162 short channel;
163 unsigned char slave_addr;
164 unsigned char lun;
165 };
166
167The "channel" here is generally zero, but some devices support more
168than one channel, it corresponds to the channel as defined in the IPMI
169spec.
170
171
172Messages
173--------
174
175Messages are defined as:
176
177struct ipmi_msg
178{
179 unsigned char netfn;
180 unsigned char lun;
181 unsigned char cmd;
182 unsigned char *data;
183 int data_len;
184};
185
186The driver takes care of adding/stripping the header information. The
187data portion is just the data to be send (do NOT put addressing info
188here) or the response. Note that the completion code of a response is
189the first item in "data", it is not stripped out because that is how
190all the messages are defined in the spec (and thus makes counting the
191offsets a little easier :-).
192
193When using the IOCTL interface from userland, you must provide a block
194of data for "data", fill it, and set data_len to the length of the
195block of data, even when receiving messages. Otherwise the driver
196will have no place to put the message.
197
198Messages coming up from the message handler in kernelland will come in
199as:
200
201 struct ipmi_recv_msg
202 {
203 struct list_head link;
204
205 /* The type of message as defined in the "Receive Types"
206 defines above. */
207 int recv_type;
208
209 ipmi_user_t *user;
210 struct ipmi_addr addr;
211 long msgid;
212 struct ipmi_msg msg;
213
214 /* Call this when done with the message. It will presumably free
215 the message and do any other necessary cleanup. */
216 void (*done)(struct ipmi_recv_msg *msg);
217
218 /* Place-holder for the data, don't make any assumptions about
219 the size or existence of this, since it may change. */
220 unsigned char msg_data[IPMI_MAX_MSG_LENGTH];
221 };
222
223You should look at the receive type and handle the message
224appropriately.
225
226
227The Upper Layer Interface (Message Handler)
228-------------------------------------------
229
230The upper layer of the interface provides the users with a consistent
231view of the IPMI interfaces. It allows multiple SMI interfaces to be
232addressed (because some boards actually have multiple BMCs on them)
233and the user should not have to care what type of SMI is below them.
234
235
236Creating the User
237
238To user the message handler, you must first create a user using
239ipmi_create_user. The interface number specifies which SMI you want
240to connect to, and you must supply callback functions to be called
241when data comes in. The callback function can run at interrupt level,
242so be careful using the callbacks. This also allows to you pass in a
243piece of data, the handler_data, that will be passed back to you on
244all calls.
245
246Once you are done, call ipmi_destroy_user() to get rid of the user.
247
248From userland, opening the device automatically creates a user, and
249closing the device automatically destroys the user.
250
251
252Messaging
253
254To send a message from kernel-land, the ipmi_request() call does
255pretty much all message handling. Most of the parameter are
256self-explanatory. However, it takes a "msgid" parameter. This is NOT
257the sequence number of messages. It is simply a long value that is
258passed back when the response for the message is returned. You may
259use it for anything you like.
260
261Responses come back in the function pointed to by the ipmi_recv_hndl
262field of the "handler" that you passed in to ipmi_create_user().
263Remember again, these may be running at interrupt level. Remember to
264look at the receive type, too.
265
266From userland, you fill out an ipmi_req_t structure and use the
267IPMICTL_SEND_COMMAND ioctl. For incoming stuff, you can use select()
268or poll() to wait for messages to come in. However, you cannot use
269read() to get them, you must call the IPMICTL_RECEIVE_MSG with the
270ipmi_recv_t structure to actually get the message. Remember that you
271must supply a pointer to a block of data in the msg.data field, and
272you must fill in the msg.data_len field with the size of the data.
273This gives the receiver a place to actually put the message.
274
275If the message cannot fit into the data you provide, you will get an
276EMSGSIZE error and the driver will leave the data in the receive
277queue. If you want to get it and have it truncate the message, us
278the IPMICTL_RECEIVE_MSG_TRUNC ioctl.
279
280When you send a command (which is defined by the lowest-order bit of
281the netfn per the IPMI spec) on the IPMB bus, the driver will
282automatically assign the sequence number to the command and save the
283command. If the response is not receive in the IPMI-specified 5
284seconds, it will generate a response automatically saying the command
285timed out. If an unsolicited response comes in (if it was after 5
286seconds, for instance), that response will be ignored.
287
288In kernelland, after you receive a message and are done with it, you
289MUST call ipmi_free_recv_msg() on it, or you will leak messages. Note
290that you should NEVER mess with the "done" field of a message, that is
291required to properly clean up the message.
292
293Note that when sending, there is an ipmi_request_supply_msgs() call
294that lets you supply the smi and receive message. This is useful for
295pieces of code that need to work even if the system is out of buffers
296(the watchdog timer uses this, for instance). You supply your own
297buffer and own free routines. This is not recommended for normal use,
298though, since it is tricky to manage your own buffers.
299
300
301Events and Incoming Commands
302
303The driver takes care of polling for IPMI events and receiving
304commands (commands are messages that are not responses, they are
305commands that other things on the IPMB bus have sent you). To receive
306these, you must register for them, they will not automatically be sent
307to you.
308
309To receive events, you must call ipmi_set_gets_events() and set the
310"val" to non-zero. Any events that have been received by the driver
311since startup will immediately be delivered to the first user that
312registers for events. After that, if multiple users are registered
313for events, they will all receive all events that come in.
314
315For receiving commands, you have to individually register commands you
316want to receive. Call ipmi_register_for_cmd() and supply the netfn
Corey Minyardc69c3122006-09-30 23:27:56 -0700317and command name for each command you want to receive. You also
318specify a bitmask of the channels you want to receive the command from
319(or use IPMI_CHAN_ALL for all channels if you don't care). Only one
320user may be registered for each netfn/cmd/channel, but different users
321may register for different commands, or the same command if the
322channel bitmasks do not overlap.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323
324From userland, equivalent IOCTLs are provided to do these functions.
325
326
327The Lower Layer (SMI) Interface
328-------------------------------
329
330As mentioned before, multiple SMI interfaces may be registered to the
331message handler, each of these is assigned an interface number when
332they register with the message handler. They are generally assigned
333in the order they register, although if an SMI unregisters and then
334another one registers, all bets are off.
335
336The ipmi_smi.h defines the interface for management interfaces, see
337that for more details.
338
339
340The SI Driver
341-------------
342
343The SI driver allows up to 4 KCS or SMIC interfaces to be configured
344in the system. By default, scan the ACPI tables for interfaces, and
345if it doesn't find any the driver will attempt to register one KCS
346interface at the spec-specified I/O port 0xca2 without interrupts.
347You can change this at module load time (for a module) with:
348
349 modprobe ipmi_si.o type=<type1>,<type2>....
350 ports=<port1>,<port2>... addrs=<addr1>,<addr2>...
351 irqs=<irq1>,<irq2>... trydefaults=[0|1]
352 regspacings=<sp1>,<sp2>,... regsizes=<size1>,<size2>,...
353 regshifts=<shift1>,<shift2>,...
354 slave_addrs=<addr1>,<addr2>,...
Corey Minyarda51f4a82006-10-03 01:13:59 -0700355 force_kipmid=<enable1>,<enable2>,...
Martin Wilckae74e822010-03-10 15:23:06 -0800356 kipmid_max_busy_us=<ustime1>,<ustime2>,...
Corey Minyardb361e272006-12-06 20:41:07 -0800357 unload_when_empty=[0|1]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358
359Each of these except si_trydefaults is a list, the first item for the
360first interface, second item for the second interface, etc.
361
362The si_type may be either "kcs", "smic", or "bt". If you leave it blank, it
363defaults to "kcs".
364
365If you specify si_addrs as non-zero for an interface, the driver will
366use the memory address given as the address of the device. This
367overrides si_ports.
368
369If you specify si_ports as non-zero for an interface, the driver will
370use the I/O port given as the device address.
371
372If you specify si_irqs as non-zero for an interface, the driver will
373attempt to use the given interrupt for the device.
374
375si_trydefaults sets whether the standard IPMI interface at 0xca2 and
376any interfaces specified by ACPE are tried. By default, the driver
377tries it, set this value to zero to turn this off.
378
379The next three parameters have to do with register layout. The
380registers used by the interfaces may not appear at successive
381locations and they may not be in 8-bit registers. These parameters
382allow the layout of the data in the registers to be more precisely
383specified.
384
385The regspacings parameter give the number of bytes between successive
386register start addresses. For instance, if the regspacing is set to 4
387and the start address is 0xca2, then the address for the second
388register would be 0xca6. This defaults to 1.
389
390The regsizes parameter gives the size of a register, in bytes. The
391data used by IPMI is 8-bits wide, but it may be inside a larger
392register. This parameter allows the read and write type to specified.
393It may be 1, 2, 4, or 8. The default is 1.
394
395Since the register size may be larger than 32 bits, the IPMI data may not
396be in the lower 8 bits. The regshifts parameter give the amount to shift
397the data to get to the actual IPMI data.
398
399The slave_addrs specifies the IPMI address of the local BMC. This is
400usually 0x20 and the driver defaults to that, but in case it's not, it
401can be specified when the driver starts up.
402
Corey Minyarda51f4a82006-10-03 01:13:59 -0700403The force_ipmid parameter forcefully enables (if set to 1) or disables
404(if set to 0) the kernel IPMI daemon. Normally this is auto-detected
405by the driver, but systems with broken interrupts might need an enable,
406or users that don't want the daemon (don't need the performance, don't
407want the CPU hit) can disable it.
408
Corey Minyardb361e272006-12-06 20:41:07 -0800409If unload_when_empty is set to 1, the driver will be unloaded if it
410doesn't find any interfaces or all the interfaces fail to work. The
411default is one. Setting to 0 is useful with the hotmod, but is
412obviously only useful for modules.
413
Corey Minyarda51f4a82006-10-03 01:13:59 -0700414When compiled into the kernel, the parameters can be specified on the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415kernel command line as:
416
417 ipmi_si.type=<type1>,<type2>...
418 ipmi_si.ports=<port1>,<port2>... ipmi_si.addrs=<addr1>,<addr2>...
419 ipmi_si.irqs=<irq1>,<irq2>... ipmi_si.trydefaults=[0|1]
420 ipmi_si.regspacings=<sp1>,<sp2>,...
421 ipmi_si.regsizes=<size1>,<size2>,...
422 ipmi_si.regshifts=<shift1>,<shift2>,...
423 ipmi_si.slave_addrs=<addr1>,<addr2>,...
Corey Minyarda51f4a82006-10-03 01:13:59 -0700424 ipmi_si.force_kipmid=<enable1>,<enable2>,...
Martin Wilckae74e822010-03-10 15:23:06 -0800425 ipmi_si.kipmid_max_busy_us=<ustime1>,<ustime2>,...
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426
427It works the same as the module parameters of the same names.
428
429By default, the driver will attempt to detect any device specified by
430ACPI, and if none of those then a KCS device at the spec-specified
4310xca2. If you want to turn this off, set the "trydefaults" option to
432false.
433
Corey Minyard650dd0c2007-10-18 03:07:09 -0700434If your IPMI interface does not support interrupts and is a KCS or
435SMIC interface, the IPMI driver will start a kernel thread for the
436interface to help speed things up. This is a low-priority kernel
437thread that constantly polls the IPMI driver while an IPMI operation
438is in progress. The force_kipmid module parameter will all the user to
439force this thread on or off. If you force it off and don't have
440interrupts, the driver will run VERY slowly. Don't blame me,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441these interfaces suck.
442
Martin Wilckae74e822010-03-10 15:23:06 -0800443Unfortunately, this thread can use a lot of CPU depending on the
444interface's performance. This can waste a lot of CPU and cause
445various issues with detecting idle CPU and using extra power. To
446avoid this, the kipmid_max_busy_us sets the maximum amount of time, in
447microseconds, that kipmid will spin before sleeping for a tick. This
448value sets a balance between performance and CPU waste and needs to be
449tuned to your needs. Maybe, someday, auto-tuning will be added, but
450that's not a simple thing and even the auto-tuning would need to be
451tuned to the user's desired performance.
452
Corey Minyardb361e272006-12-06 20:41:07 -0800453The driver supports a hot add and remove of interfaces. This way,
454interfaces can be added or removed after the kernel is up and running.
Corey Minyard650dd0c2007-10-18 03:07:09 -0700455This is done using /sys/modules/ipmi_si/parameters/hotmod, which is a
456write-only parameter. You write a string to this interface. The string
457has the format:
Corey Minyardb361e272006-12-06 20:41:07 -0800458 <op1>[:op2[:op3...]]
459The "op"s are:
460 add|remove,kcs|bt|smic,mem|i/o,<address>[,<opt1>[,<opt2>[,...]]]
461You can specify more than one interface on the line. The "opt"s are:
462 rsp=<regspacing>
463 rsi=<regsize>
464 rsh=<regshift>
465 irq=<irq>
466 ipmb=<ipmb slave addr>
467and these have the same meanings as discussed above. Note that you
468can also use this on the kernel command line for a more compact format
469for specifying an interface. Note that when removing an interface,
470only the first three parameters (si type, address type, and address)
471are used for the comparison. Any options are ignored for removing.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473
474Other Pieces
475------------
476
Zhao Yakui37bf5012010-12-08 10:10:17 +0800477Get the detailed info related with the IPMI device
478--------------------------------------------------
479
480Some users need more detailed information about a device, like where
481the address came from or the raw base device for the IPMI interface.
482You can use the IPMI smi_watcher to catch the IPMI interfaces as they
483come or go, and to grab the information, you can use the function
484ipmi_get_smi_info(), which returns the following structure:
485
486struct ipmi_smi_info {
487 enum ipmi_addr_src addr_src;
488 struct device *dev;
489 union {
490 struct {
491 void *acpi_handle;
492 } acpi_info;
493 } addr_info;
494};
495
496Currently special info for only for SI_ACPI address sources is
497returned. Others may be added as necessary.
498
499Note that the dev pointer is included in the above structure, and
500assuming ipmi_smi_get_info returns success, you must call put_device
501on the dev pointer.
502
503
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504Watchdog
505--------
506
507A watchdog timer is provided that implements the Linux-standard
508watchdog timer interface. It has three module parameters that can be
509used to control it:
510
511 modprobe ipmi_watchdog timeout=<t> pretimeout=<t> action=<action type>
512 preaction=<preaction type> preop=<preop type> start_now=x
Corey Minyardb2c03942006-12-06 20:41:00 -0800513 nowayout=x ifnum_to_use=n
514
515ifnum_to_use specifies which interface the watchdog timer should use.
516The default is -1, which means to pick the first one registered.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517
518The timeout is the number of seconds to the action, and the pretimeout
519is the amount of seconds before the reset that the pre-timeout panic will
520occur (if pretimeout is zero, then pretimeout will not be enabled). Note
521that the pretimeout is the time before the final timeout. So if the
522timeout is 50 seconds and the pretimeout is 10 seconds, then the pretimeout
523will occur in 40 second (10 seconds before the timeout).
524
525The action may be "reset", "power_cycle", or "power_off", and
526specifies what to do when the timer times out, and defaults to
527"reset".
528
529The preaction may be "pre_smi" for an indication through the SMI
530interface, "pre_int" for an indication through the SMI with an
531interrupts, and "pre_nmi" for a NMI on a preaction. This is how
532the driver is informed of the pretimeout.
533
534The preop may be set to "preop_none" for no operation on a pretimeout,
535"preop_panic" to set the preoperation to panic, or "preop_give_data"
536to provide data to read from the watchdog device when the pretimeout
537occurs. A "pre_nmi" setting CANNOT be used with "preop_give_data"
538because you can't do data operations from an NMI.
539
540When preop is set to "preop_give_data", one byte comes ready to read
541on the device when the pretimeout occurs. Select and fasync work on
542the device, as well.
543
544If start_now is set to 1, the watchdog timer will start running as
545soon as the driver is loaded.
546
547If nowayout is set to 1, the watchdog timer will not stop when the
548watchdog device is closed. The default value of nowayout is true
549if the CONFIG_WATCHDOG_NOWAYOUT option is enabled, or false if not.
550
551When compiled into the kernel, the kernel command line is available
552for configuring the watchdog:
553
554 ipmi_watchdog.timeout=<t> ipmi_watchdog.pretimeout=<t>
555 ipmi_watchdog.action=<action type>
556 ipmi_watchdog.preaction=<preaction type>
557 ipmi_watchdog.preop=<preop type>
558 ipmi_watchdog.start_now=x
559 ipmi_watchdog.nowayout=x
560
561The options are the same as the module parameter options.
562
563The watchdog will panic and start a 120 second reset timeout if it
564gets a pre-action. During a panic or a reboot, the watchdog will
565start a 120 timer if it is running to make sure the reboot occurs.
566
Corey Minyard612b5a82007-10-18 03:07:10 -0700567Note that if you use the NMI preaction for the watchdog, you MUST NOT
568use the nmi watchdog. There is no reasonable way to tell if an NMI
569comes from the IPMI controller, so it must assume that if it gets an
570otherwise unhandled NMI, it must be from IPMI and it will panic
571immediately.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572
573Once you open the watchdog timer, you must write a 'V' character to the
574device to close it, or the timer will not stop. This is a new semantic
575for the driver, but makes it consistent with the rest of the watchdog
576drivers in Linux.
Corey Minyard845e78a2005-06-23 22:01:39 -0700577
578
579Panic Timeouts
580--------------
581
582The OpenIPMI driver supports the ability to put semi-custom and custom
583events in the system event log if a panic occurs. if you enable the
584'Generate a panic event to all BMCs on a panic' option, you will get
585one event on a panic in a standard IPMI event format. If you enable
586the 'Generate OEM events containing the panic string' option, you will
587also get a bunch of OEM events holding the panic string.
588
589
590The field settings of the events are:
591* Generator ID: 0x21 (kernel)
592* EvM Rev: 0x03 (this event is formatting in IPMI 1.0 format)
593* Sensor Type: 0x20 (OS critical stop sensor)
594* Sensor #: The first byte of the panic string (0 if no panic string)
595* Event Dir | Event Type: 0x6f (Assertion, sensor-specific event info)
596* Event Data 1: 0xa1 (Runtime stop in OEM bytes 2 and 3)
597* Event data 2: second byte of panic string
598* Event data 3: third byte of panic string
599See the IPMI spec for the details of the event layout. This event is
600always sent to the local management controller. It will handle routing
601the message to the right place
602
603Other OEM events have the following format:
604Record ID (bytes 0-1): Set by the SEL.
605Record type (byte 2): 0xf0 (OEM non-timestamped)
606byte 3: The slave address of the card saving the panic
607byte 4: A sequence number (starting at zero)
608The rest of the bytes (11 bytes) are the panic string. If the panic string
609is longer than 11 bytes, multiple messages will be sent with increasing
610sequence numbers.
611
612Because you cannot send OEM events using the standard interface, this
613function will attempt to find an SEL and add the events there. It
614will first query the capabilities of the local management controller.
615If it has an SEL, then they will be stored in the SEL of the local
616management controller. If not, and the local management controller is
617an event generator, the event receiver from the local management
618controller will be queried and the events sent to the SEL on that
619device. Otherwise, the events go nowhere since there is nowhere to
620send them.
Corey Minyard3b625942005-06-23 22:01:42 -0700621
622
623Poweroff
624--------
625
626If the poweroff capability is selected, the IPMI driver will install
627a shutdown function into the standard poweroff function pointer. This
628is in the ipmi_poweroff module. When the system requests a powerdown,
629it will send the proper IPMI commands to do this. This is supported on
630several platforms.
631
Corey Minyard8c702e12005-09-06 15:18:46 -0700632There is a module parameter named "poweroff_powercycle" that may
633either be zero (do a power down) or non-zero (do a power cycle, power
634the system off, then power it on in a few seconds). Setting
635ipmi_poweroff.poweroff_control=x will do the same thing on the kernel
636command line. The parameter is also available via the proc filesystem
637in /proc/sys/dev/ipmi/poweroff_powercycle. Note that if the system
638does not support power cycling, it will always do the power off.
Corey Minyard3b625942005-06-23 22:01:42 -0700639
Corey Minyardb2c03942006-12-06 20:41:00 -0800640The "ifnum_to_use" parameter specifies which interface the poweroff
641code should use. The default is -1, which means to pick the first one
642registered.
643
Corey Minyard3b625942005-06-23 22:01:42 -0700644Note that if you have ACPI enabled, the system will prefer using ACPI to
645power off.