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diff --git a/Documentation/driver-api/ipmi.rst b/Documentation/driver-api/ipmi.rst new file mode 100644 index 000000000..bc281f10c --- /dev/null +++ b/Documentation/driver-api/ipmi.rst @@ -0,0 +1,750 @@ +===================== +The Linux IPMI Driver +===================== + +:Author: Corey Minyard <minyard@mvista.com> / <minyard@acm.org> + +The Intelligent Platform Management Interface, or IPMI, is a +standard for controlling intelligent devices that monitor a system. +It provides for dynamic discovery of sensors in the system and the +ability to monitor the sensors and be informed when the sensor's +values change or go outside certain boundaries. It also has a +standardized database for field-replaceable units (FRUs) and a watchdog +timer. + +To use this, you need an interface to an IPMI controller in your +system (called a Baseboard Management Controller, or BMC) and +management software that can use the IPMI system. + +This document describes how to use the IPMI driver for Linux. If you +are not familiar with IPMI itself, see the web site at +https://www.intel.com/design/servers/ipmi/index.htm. IPMI is a big +subject and I can't cover it all here! + +Configuration +------------- + +The Linux IPMI driver is modular, which means you have to pick several +things to have it work right depending on your hardware. Most of +these are available in the 'Character Devices' menu then the IPMI +menu. + +No matter what, you must pick 'IPMI top-level message handler' to use +IPMI. What you do beyond that depends on your needs and hardware. + +The message handler does not provide any user-level interfaces. +Kernel code (like the watchdog) can still use it. If you need access +from userland, you need to select 'Device interface for IPMI' if you +want access through a device driver. + +The driver interface depends on your hardware. If your system +properly provides the SMBIOS info for IPMI, the driver will detect it +and just work. If you have a board with a standard interface (These +will generally be either "KCS", "SMIC", or "BT", consult your hardware +manual), choose the 'IPMI SI handler' option. A driver also exists +for direct I2C access to the IPMI management controller. Some boards +support this, but it is unknown if it will work on every board. For +this, choose 'IPMI SMBus handler', but be ready to try to do some +figuring to see if it will work on your system if the SMBIOS/APCI +information is wrong or not present. It is fairly safe to have both +these enabled and let the drivers auto-detect what is present. + +You should generally enable ACPI on your system, as systems with IPMI +can have ACPI tables describing them. + +If you have a standard interface and the board manufacturer has done +their job correctly, the IPMI controller should be automatically +detected (via ACPI or SMBIOS tables) and should just work. Sadly, +many boards do not have this information. The driver attempts +standard defaults, but they may not work. If you fall into this +situation, you need to read the section below named 'The SI Driver' or +"The SMBus Driver" on how to hand-configure your system. + +IPMI defines a standard watchdog timer. You can enable this with the +'IPMI Watchdog Timer' config option. If you compile the driver into +the kernel, then via a kernel command-line option you can have the +watchdog timer start as soon as it initializes. It also have a lot +of other options, see the 'Watchdog' section below for more details. +Note that you can also have the watchdog continue to run if it is +closed (by default it is disabled on close). Go into the 'Watchdog +Cards' menu, enable 'Watchdog Timer Support', and enable the option +'Disable watchdog shutdown on close'. + +IPMI systems can often be powered off using IPMI commands. Select +'IPMI Poweroff' to do this. The driver will auto-detect if the system +can be powered off by IPMI. It is safe to enable this even if your +system doesn't support this option. This works on ATCA systems, the +Radisys CPI1 card, and any IPMI system that supports standard chassis +management commands. + +If you want the driver to put an event into the event log on a panic, +enable the 'Generate a panic event to all BMCs on a panic' option. If +you want the whole panic string put into the event log using OEM +events, enable the 'Generate OEM events containing the panic string' +option. You can also enable these dynamically by setting the module +parameter named "panic_op" in the ipmi_msghandler module to "event" +or "string". Setting that parameter to "none" disables this function. + +Basic Design +------------ + +The Linux IPMI driver is designed to be very modular and flexible, you +only need to take the pieces you need and you can use it in many +different ways. Because of that, it's broken into many chunks of +code. These chunks (by module name) are: + +ipmi_msghandler - This is the central piece of software for the IPMI +system. It handles all messages, message timing, and responses. The +IPMI users tie into this, and the IPMI physical interfaces (called +System Management Interfaces, or SMIs) also tie in here. This +provides the kernelland interface for IPMI, but does not provide an +interface for use by application processes. + +ipmi_devintf - This provides a userland IOCTL interface for the IPMI +driver, each open file for this device ties in to the message handler +as an IPMI user. + +ipmi_si - A driver for various system interfaces. This supports KCS, +SMIC, and BT interfaces. Unless you have an SMBus interface or your +own custom interface, you probably need to use this. + +ipmi_ssif - A driver for accessing BMCs on the SMBus. It uses the +I2C kernel driver's SMBus interfaces to send and receive IPMI messages +over the SMBus. + +ipmi_powernv - A driver for access BMCs on POWERNV systems. + +ipmi_watchdog - IPMI requires systems to have a very capable watchdog +timer. This driver implements the standard Linux watchdog timer +interface on top of the IPMI message handler. + +ipmi_poweroff - Some systems support the ability to be turned off via +IPMI commands. + +bt-bmc - This is not part of the main driver, but instead a driver for +accessing a BMC-side interface of a BT interface. It is used on BMCs +running Linux to provide an interface to the host. + +These are all individually selectable via configuration options. + +Much documentation for the interface is in the include files. The +IPMI include files are: + +linux/ipmi.h - Contains the user interface and IOCTL interface for IPMI. + +linux/ipmi_smi.h - Contains the interface for system management interfaces +(things that interface to IPMI controllers) to use. + +linux/ipmi_msgdefs.h - General definitions for base IPMI messaging. + + +Addressing +---------- + +The IPMI addressing works much like IP addresses, you have an overlay +to handle the different address types. The overlay is:: + + struct ipmi_addr + { + int addr_type; + short channel; + char data[IPMI_MAX_ADDR_SIZE]; + }; + +The addr_type determines what the address really is. The driver +currently understands two different types of addresses. + +"System Interface" addresses are defined as:: + + struct ipmi_system_interface_addr + { + int addr_type; + short channel; + }; + +and the type is IPMI_SYSTEM_INTERFACE_ADDR_TYPE. This is used for talking +straight to the BMC on the current card. The channel must be +IPMI_BMC_CHANNEL. + +Messages that are destined to go out on the IPMB bus use the +IPMI_IPMB_ADDR_TYPE address type. The format is:: + + struct ipmi_ipmb_addr + { + int addr_type; + short channel; + unsigned char slave_addr; + unsigned char lun; + }; + +The "channel" here is generally zero, but some devices support more +than one channel, it corresponds to the channel as defined in the IPMI +spec. + + +Messages +-------- + +Messages are defined as:: + + struct ipmi_msg + { + unsigned char netfn; + unsigned char lun; + unsigned char cmd; + unsigned char *data; + int data_len; + }; + +The driver takes care of adding/stripping the header information. The +data portion is just the data to be send (do NOT put addressing info +here) or the response. Note that the completion code of a response is +the first item in "data", it is not stripped out because that is how +all the messages are defined in the spec (and thus makes counting the +offsets a little easier :-). + +When using the IOCTL interface from userland, you must provide a block +of data for "data", fill it, and set data_len to the length of the +block of data, even when receiving messages. Otherwise the driver +will have no place to put the message. + +Messages coming up from the message handler in kernelland will come in +as:: + + struct ipmi_recv_msg + { + struct list_head link; + + /* The type of message as defined in the "Receive Types" + defines above. */ + int recv_type; + + ipmi_user_t *user; + struct ipmi_addr addr; + long msgid; + struct ipmi_msg msg; + + /* Call this when done with the message. It will presumably free + the message and do any other necessary cleanup. */ + void (*done)(struct ipmi_recv_msg *msg); + + /* Place-holder for the data, don't make any assumptions about + the size or existence of this, since it may change. */ + unsigned char msg_data[IPMI_MAX_MSG_LENGTH]; + }; + +You should look at the receive type and handle the message +appropriately. + + +The Upper Layer Interface (Message Handler) +------------------------------------------- + +The upper layer of the interface provides the users with a consistent +view of the IPMI interfaces. It allows multiple SMI interfaces to be +addressed (because some boards actually have multiple BMCs on them) +and the user should not have to care what type of SMI is below them. + + +Watching For Interfaces +^^^^^^^^^^^^^^^^^^^^^^^ + +When your code comes up, the IPMI driver may or may not have detected +if IPMI devices exist. So you might have to defer your setup until +the device is detected, or you might be able to do it immediately. +To handle this, and to allow for discovery, you register an SMI +watcher with ipmi_smi_watcher_register() to iterate over interfaces +and tell you when they come and go. + + +Creating the User +^^^^^^^^^^^^^^^^^ + +To use the message handler, you must first create a user using +ipmi_create_user. The interface number specifies which SMI you want +to connect to, and you must supply callback functions to be called +when data comes in. The callback function can run at interrupt level, +so be careful using the callbacks. This also allows to you pass in a +piece of data, the handler_data, that will be passed back to you on +all calls. + +Once you are done, call ipmi_destroy_user() to get rid of the user. + +From userland, opening the device automatically creates a user, and +closing the device automatically destroys the user. + + +Messaging +^^^^^^^^^ + +To send a message from kernel-land, the ipmi_request_settime() call does +pretty much all message handling. Most of the parameter are +self-explanatory. However, it takes a "msgid" parameter. This is NOT +the sequence number of messages. It is simply a long value that is +passed back when the response for the message is returned. You may +use it for anything you like. + +Responses come back in the function pointed to by the ipmi_recv_hndl +field of the "handler" that you passed in to ipmi_create_user(). +Remember again, these may be running at interrupt level. Remember to +look at the receive type, too. + +From userland, you fill out an ipmi_req_t structure and use the +IPMICTL_SEND_COMMAND ioctl. For incoming stuff, you can use select() +or poll() to wait for messages to come in. However, you cannot use +read() to get them, you must call the IPMICTL_RECEIVE_MSG with the +ipmi_recv_t structure to actually get the message. Remember that you +must supply a pointer to a block of data in the msg.data field, and +you must fill in the msg.data_len field with the size of the data. +This gives the receiver a place to actually put the message. + +If the message cannot fit into the data you provide, you will get an +EMSGSIZE error and the driver will leave the data in the receive +queue. If you want to get it and have it truncate the message, us +the IPMICTL_RECEIVE_MSG_TRUNC ioctl. + +When you send a command (which is defined by the lowest-order bit of +the netfn per the IPMI spec) on the IPMB bus, the driver will +automatically assign the sequence number to the command and save the +command. If the response is not receive in the IPMI-specified 5 +seconds, it will generate a response automatically saying the command +timed out. If an unsolicited response comes in (if it was after 5 +seconds, for instance), that response will be ignored. + +In kernelland, after you receive a message and are done with it, you +MUST call ipmi_free_recv_msg() on it, or you will leak messages. Note +that you should NEVER mess with the "done" field of a message, that is +required to properly clean up the message. + +Note that when sending, there is an ipmi_request_supply_msgs() call +that lets you supply the smi and receive message. This is useful for +pieces of code that need to work even if the system is out of buffers +(the watchdog timer uses this, for instance). You supply your own +buffer and own free routines. This is not recommended for normal use, +though, since it is tricky to manage your own buffers. + + +Events and Incoming Commands +^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The driver takes care of polling for IPMI events and receiving +commands (commands are messages that are not responses, they are +commands that other things on the IPMB bus have sent you). To receive +these, you must register for them, they will not automatically be sent +to you. + +To receive events, you must call ipmi_set_gets_events() and set the +"val" to non-zero. Any events that have been received by the driver +since startup will immediately be delivered to the first user that +registers for events. After that, if multiple users are registered +for events, they will all receive all events that come in. + +For receiving commands, you have to individually register commands you +want to receive. Call ipmi_register_for_cmd() and supply the netfn +and command name for each command you want to receive. You also +specify a bitmask of the channels you want to receive the command from +(or use IPMI_CHAN_ALL for all channels if you don't care). Only one +user may be registered for each netfn/cmd/channel, but different users +may register for different commands, or the same command if the +channel bitmasks do not overlap. + +From userland, equivalent IOCTLs are provided to do these functions. + + +The Lower Layer (SMI) Interface +------------------------------- + +As mentioned before, multiple SMI interfaces may be registered to the +message handler, each of these is assigned an interface number when +they register with the message handler. They are generally assigned +in the order they register, although if an SMI unregisters and then +another one registers, all bets are off. + +The ipmi_smi.h defines the interface for management interfaces, see +that for more details. + + +The SI Driver +------------- + +The SI driver allows KCS, BT, and SMIC interfaces to be configured +in the system. It discovers interfaces through a host of different +methods, depending on the system. + +You can specify up to four interfaces on the module load line and +control some module parameters:: + + modprobe ipmi_si.o type=<type1>,<type2>.... + ports=<port1>,<port2>... addrs=<addr1>,<addr2>... + irqs=<irq1>,<irq2>... + regspacings=<sp1>,<sp2>,... regsizes=<size1>,<size2>,... + regshifts=<shift1>,<shift2>,... + slave_addrs=<addr1>,<addr2>,... + force_kipmid=<enable1>,<enable2>,... + kipmid_max_busy_us=<ustime1>,<ustime2>,... + unload_when_empty=[0|1] + trydmi=[0|1] tryacpi=[0|1] + tryplatform=[0|1] trypci=[0|1] + +Each of these except try... items is a list, the first item for the +first interface, second item for the second interface, etc. + +The si_type may be either "kcs", "smic", or "bt". If you leave it blank, it +defaults to "kcs". + +If you specify addrs as non-zero for an interface, the driver will +use the memory address given as the address of the device. This +overrides si_ports. + +If you specify ports as non-zero for an interface, the driver will +use the I/O port given as the device address. + +If you specify irqs as non-zero for an interface, the driver will +attempt to use the given interrupt for the device. + +The other try... items disable discovery by their corresponding +names. These are all enabled by default, set them to zero to disable +them. The tryplatform disables openfirmware. + +The next three parameters have to do with register layout. The +registers used by the interfaces may not appear at successive +locations and they may not be in 8-bit registers. These parameters +allow the layout of the data in the registers to be more precisely +specified. + +The regspacings parameter give the number of bytes between successive +register start addresses. For instance, if the regspacing is set to 4 +and the start address is 0xca2, then the address for the second +register would be 0xca6. This defaults to 1. + +The regsizes parameter gives the size of a register, in bytes. The +data used by IPMI is 8-bits wide, but it may be inside a larger +register. This parameter allows the read and write type to specified. +It may be 1, 2, 4, or 8. The default is 1. + +Since the register size may be larger than 32 bits, the IPMI data may not +be in the lower 8 bits. The regshifts parameter give the amount to shift +the data to get to the actual IPMI data. + +The slave_addrs specifies the IPMI address of the local BMC. This is +usually 0x20 and the driver defaults to that, but in case it's not, it +can be specified when the driver starts up. + +The force_ipmid parameter forcefully enables (if set to 1) or disables +(if set to 0) the kernel IPMI daemon. Normally this is auto-detected +by the driver, but systems with broken interrupts might need an enable, +or users that don't want the daemon (don't need the performance, don't +want the CPU hit) can disable it. + +If unload_when_empty is set to 1, the driver will be unloaded if it +doesn't find any interfaces or all the interfaces fail to work. The +default is one. Setting to 0 is useful with the hotmod, but is +obviously only useful for modules. + +When compiled into the kernel, the parameters can be specified on the +kernel command line as:: + + ipmi_si.type=<type1>,<type2>... + ipmi_si.ports=<port1>,<port2>... ipmi_si.addrs=<addr1>,<addr2>... + ipmi_si.irqs=<irq1>,<irq2>... + ipmi_si.regspacings=<sp1>,<sp2>,... + ipmi_si.regsizes=<size1>,<size2>,... + ipmi_si.regshifts=<shift1>,<shift2>,... + ipmi_si.slave_addrs=<addr1>,<addr2>,... + ipmi_si.force_kipmid=<enable1>,<enable2>,... + ipmi_si.kipmid_max_busy_us=<ustime1>,<ustime2>,... + +It works the same as the module parameters of the same names. + +If your IPMI interface does not support interrupts and is a KCS or +SMIC interface, the IPMI driver will start a kernel thread for the +interface to help speed things up. This is a low-priority kernel +thread that constantly polls the IPMI driver while an IPMI operation +is in progress. The force_kipmid module parameter will all the user to +force this thread on or off. If you force it off and don't have +interrupts, the driver will run VERY slowly. Don't blame me, +these interfaces suck. + +Unfortunately, this thread can use a lot of CPU depending on the +interface's performance. This can waste a lot of CPU and cause +various issues with detecting idle CPU and using extra power. To +avoid this, the kipmid_max_busy_us sets the maximum amount of time, in +microseconds, that kipmid will spin before sleeping for a tick. This +value sets a balance between performance and CPU waste and needs to be +tuned to your needs. Maybe, someday, auto-tuning will be added, but +that's not a simple thing and even the auto-tuning would need to be +tuned to the user's desired performance. + +The driver supports a hot add and remove of interfaces. This way, +interfaces can be added or removed after the kernel is up and running. +This is done using /sys/modules/ipmi_si/parameters/hotmod, which is a +write-only parameter. You write a string to this interface. The string +has the format:: + + <op1>[:op2[:op3...]] + +The "op"s are:: + + add|remove,kcs|bt|smic,mem|i/o,<address>[,<opt1>[,<opt2>[,...]]] + +You can specify more than one interface on the line. The "opt"s are:: + + rsp=<regspacing> + rsi=<regsize> + rsh=<regshift> + irq=<irq> + ipmb=<ipmb slave addr> + +and these have the same meanings as discussed above. Note that you +can also use this on the kernel command line for a more compact format +for specifying an interface. Note that when removing an interface, +only the first three parameters (si type, address type, and address) +are used for the comparison. Any options are ignored for removing. + +The SMBus Driver (SSIF) +----------------------- + +The SMBus driver allows up to 4 SMBus devices to be configured in the +system. By default, the driver will only register with something it +finds in DMI or ACPI tables. You can change this +at module load time (for a module) with:: + + modprobe ipmi_ssif.o + addr=<i2caddr1>[,<i2caddr2>[,...]] + adapter=<adapter1>[,<adapter2>[...]] + dbg=<flags1>,<flags2>... + slave_addrs=<addr1>,<addr2>,... + tryacpi=[0|1] trydmi=[0|1] + [dbg_probe=1] + alerts_broken + +The addresses are normal I2C addresses. The adapter is the string +name of the adapter, as shown in /sys/class/i2c-adapter/i2c-<n>/name. +It is *NOT* i2c-<n> itself. Also, the comparison is done ignoring +spaces, so if the name is "This is an I2C chip" you can say +adapter_name=ThisisanI2cchip. This is because it's hard to pass in +spaces in kernel parameters. + +The debug flags are bit flags for each BMC found, they are: +IPMI messages: 1, driver state: 2, timing: 4, I2C probe: 8 + +The tryxxx parameters can be used to disable detecting interfaces +from various sources. + +Setting dbg_probe to 1 will enable debugging of the probing and +detection process for BMCs on the SMBusses. + +The slave_addrs specifies the IPMI address of the local BMC. This is +usually 0x20 and the driver defaults to that, but in case it's not, it +can be specified when the driver starts up. + +alerts_broken does not enable SMBus alert for SSIF. Otherwise SMBus +alert will be enabled on supported hardware. + +Discovering the IPMI compliant BMC on the SMBus can cause devices on +the I2C bus to fail. The SMBus driver writes a "Get Device ID" IPMI +message as a block write to the I2C bus and waits for a response. +This action can be detrimental to some I2C devices. It is highly +recommended that the known I2C address be given to the SMBus driver in +the smb_addr parameter unless you have DMI or ACPI data to tell the +driver what to use. + +When compiled into the kernel, the addresses can be specified on the +kernel command line as:: + + ipmb_ssif.addr=<i2caddr1>[,<i2caddr2>[...]] + ipmi_ssif.adapter=<adapter1>[,<adapter2>[...]] + ipmi_ssif.dbg=<flags1>[,<flags2>[...]] + ipmi_ssif.dbg_probe=1 + ipmi_ssif.slave_addrs=<addr1>[,<addr2>[...]] + ipmi_ssif.tryacpi=[0|1] ipmi_ssif.trydmi=[0|1] + +These are the same options as on the module command line. + +The I2C driver does not support non-blocking access or polling, so +this driver cannod to IPMI panic events, extend the watchdog at panic +time, or other panic-related IPMI functions without special kernel +patches and driver modifications. You can get those at the openipmi +web page. + +The driver supports a hot add and remove of interfaces through the I2C +sysfs interface. + +Other Pieces +------------ + +Get the detailed info related with the IPMI device +-------------------------------------------------- + +Some users need more detailed information about a device, like where +the address came from or the raw base device for the IPMI interface. +You can use the IPMI smi_watcher to catch the IPMI interfaces as they +come or go, and to grab the information, you can use the function +ipmi_get_smi_info(), which returns the following structure:: + + struct ipmi_smi_info { + enum ipmi_addr_src addr_src; + struct device *dev; + union { + struct { + void *acpi_handle; + } acpi_info; + } addr_info; + }; + +Currently special info for only for SI_ACPI address sources is +returned. Others may be added as necessary. + +Note that the dev pointer is included in the above structure, and +assuming ipmi_smi_get_info returns success, you must call put_device +on the dev pointer. + + +Watchdog +-------- + +A watchdog timer is provided that implements the Linux-standard +watchdog timer interface. It has three module parameters that can be +used to control it:: + + modprobe ipmi_watchdog timeout=<t> pretimeout=<t> action=<action type> + preaction=<preaction type> preop=<preop type> start_now=x + nowayout=x ifnum_to_use=n panic_wdt_timeout=<t> + +ifnum_to_use specifies which interface the watchdog timer should use. +The default is -1, which means to pick the first one registered. + +The timeout is the number of seconds to the action, and the pretimeout +is the amount of seconds before the reset that the pre-timeout panic will +occur (if pretimeout is zero, then pretimeout will not be enabled). Note +that the pretimeout is the time before the final timeout. So if the +timeout is 50 seconds and the pretimeout is 10 seconds, then the pretimeout +will occur in 40 second (10 seconds before the timeout). The panic_wdt_timeout +is the value of timeout which is set on kernel panic, in order to let actions +such as kdump to occur during panic. + +The action may be "reset", "power_cycle", or "power_off", and +specifies what to do when the timer times out, and defaults to +"reset". + +The preaction may be "pre_smi" for an indication through the SMI +interface, "pre_int" for an indication through the SMI with an +interrupts, and "pre_nmi" for a NMI on a preaction. This is how +the driver is informed of the pretimeout. + +The preop may be set to "preop_none" for no operation on a pretimeout, +"preop_panic" to set the preoperation to panic, or "preop_give_data" +to provide data to read from the watchdog device when the pretimeout +occurs. A "pre_nmi" setting CANNOT be used with "preop_give_data" +because you can't do data operations from an NMI. + +When preop is set to "preop_give_data", one byte comes ready to read +on the device when the pretimeout occurs. Select and fasync work on +the device, as well. + +If start_now is set to 1, the watchdog timer will start running as +soon as the driver is loaded. + +If nowayout is set to 1, the watchdog timer will not stop when the +watchdog device is closed. The default value of nowayout is true +if the CONFIG_WATCHDOG_NOWAYOUT option is enabled, or false if not. + +When compiled into the kernel, the kernel command line is available +for configuring the watchdog:: + + ipmi_watchdog.timeout=<t> ipmi_watchdog.pretimeout=<t> + ipmi_watchdog.action=<action type> + ipmi_watchdog.preaction=<preaction type> + ipmi_watchdog.preop=<preop type> + ipmi_watchdog.start_now=x + ipmi_watchdog.nowayout=x + ipmi_watchdog.panic_wdt_timeout=<t> + +The options are the same as the module parameter options. + +The watchdog will panic and start a 120 second reset timeout if it +gets a pre-action. During a panic or a reboot, the watchdog will +start a 120 timer if it is running to make sure the reboot occurs. + +Note that if you use the NMI preaction for the watchdog, you MUST NOT +use the nmi watchdog. There is no reasonable way to tell if an NMI +comes from the IPMI controller, so it must assume that if it gets an +otherwise unhandled NMI, it must be from IPMI and it will panic +immediately. + +Once you open the watchdog timer, you must write a 'V' character to the +device to close it, or the timer will not stop. This is a new semantic +for the driver, but makes it consistent with the rest of the watchdog +drivers in Linux. + + +Panic Timeouts +-------------- + +The OpenIPMI driver supports the ability to put semi-custom and custom +events in the system event log if a panic occurs. if you enable the +'Generate a panic event to all BMCs on a panic' option, you will get +one event on a panic in a standard IPMI event format. If you enable +the 'Generate OEM events containing the panic string' option, you will +also get a bunch of OEM events holding the panic string. + + +The field settings of the events are: + +* Generator ID: 0x21 (kernel) +* EvM Rev: 0x03 (this event is formatting in IPMI 1.0 format) +* Sensor Type: 0x20 (OS critical stop sensor) +* Sensor #: The first byte of the panic string (0 if no panic string) +* Event Dir | Event Type: 0x6f (Assertion, sensor-specific event info) +* Event Data 1: 0xa1 (Runtime stop in OEM bytes 2 and 3) +* Event data 2: second byte of panic string +* Event data 3: third byte of panic string + +See the IPMI spec for the details of the event layout. This event is +always sent to the local management controller. It will handle routing +the message to the right place + +Other OEM events have the following format: + +* Record ID (bytes 0-1): Set by the SEL. +* Record type (byte 2): 0xf0 (OEM non-timestamped) +* byte 3: The slave address of the card saving the panic +* byte 4: A sequence number (starting at zero) + The rest of the bytes (11 bytes) are the panic string. If the panic string + is longer than 11 bytes, multiple messages will be sent with increasing + sequence numbers. + +Because you cannot send OEM events using the standard interface, this +function will attempt to find an SEL and add the events there. It +will first query the capabilities of the local management controller. +If it has an SEL, then they will be stored in the SEL of the local +management controller. If not, and the local management controller is +an event generator, the event receiver from the local management +controller will be queried and the events sent to the SEL on that +device. Otherwise, the events go nowhere since there is nowhere to +send them. + + +Poweroff +-------- + +If the poweroff capability is selected, the IPMI driver will install +a shutdown function into the standard poweroff function pointer. This +is in the ipmi_poweroff module. When the system requests a powerdown, +it will send the proper IPMI commands to do this. This is supported on +several platforms. + +There is a module parameter named "poweroff_powercycle" that may +either be zero (do a power down) or non-zero (do a power cycle, power +the system off, then power it on in a few seconds). Setting +ipmi_poweroff.poweroff_control=x will do the same thing on the kernel +command line. The parameter is also available via the proc filesystem +in /proc/sys/dev/ipmi/poweroff_powercycle. Note that if the system +does not support power cycling, it will always do the power off. + +The "ifnum_to_use" parameter specifies which interface the poweroff +code should use. The default is -1, which means to pick the first one +registered. + +Note that if you have ACPI enabled, the system will prefer using ACPI to +power off. |