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All Rights Reserved. .\" Copyright 2016 Nexenta Systems, Inc. .\" .Dd Dec 1, 2016 .Dt CMN_ERR 9F .Os .Sh NAME .Nm cmn_err, dev_err, vcmn_err, zcmn_err, vzcmn_err .Nd display an error message or panic the system .Sh SYNOPSIS .In sys/cmn_err.h .In sys/ddi.h .In sys/sunddi.h .Ft void .Fo cmn_err .Fa "int level" .Fa "char *format" .Fa ... .Fc .Ft void .Fo dev_err .Fa "dev_info_t *dip" .Fa "int level" .Fa "char *format" .Fa ... .Fc .In sys/varargs.h .Ft void .Fo vcmn_err .Fa "int level" .Fa "char *format" .Fa "va_list ap" .Fc .In sys/types.h .Ft void .Fo zcmn_err .Fa "zoneid_t zoneid" .Fa "int level" .Fa "char *format" .Fa ... .Fc .Ft void .Fo vzcmn_err .Fa "zoneid_t zoneid" .Fa "int level" .Fa "char *format" .Fa "va_list ap" .Fc .Sh INTERFACE LEVEL Architecture independent level 1 (DDI/DKI). .Sh PARAMETERS .Ss Fn cmn_err .Bl -tag -width Ds .It Fa level A constant indicating the severity of the error condition. .It Fa format Message to be displayed. .El .Ss Fn dev_err The .Fn dev_err function works exactly like .Fn cmn_err , but includes an additional argument: .Bl -tag -width Ds .It Fa dip A pointer to the device's .Ft dev_info structure. .El .Ss Fn vcmn_err The .Fn vcmn_err function takes .Fa level and .Fa format as described for .Fn cmn_err , but its third argument is different: .Bl -tag -width Ds .It Fa ap Variable argument list passed to the function. .El .Ss Fn zcmn_err The .Fn zcmn_err function works exactly like .Fn cmn_err , but includes an additional argument: .Bl -tag -width Ds .It Fa zoneid Zone to which log messages should be directed. See .Xr zones 5 . .El .Ss Fn vzcmn_err The .Fn vzcmn_err function works exactly like .Fn vcmn_err , but includes an additional argument: .Bl -tag -width Ds .It Fa zoneid Zone to which log messages should be directed. See .Xr zones 5 . .El .Sh DESCRIPTION .Ss Fn cmn_err The .Fn cmn_err function displays a specified message on the console. .Fn cmn_err can also panic the system. When the system panics, it attempts to save recent changes to data, display a .Qq panic message on the console, attempt to write a core file, and halt system processing. See the .Sy CE_PANIC .Fa level below. .Pp .Fa level is a constant indicating the severity of the error condition. The four severity levels are: .Bl -tag -width "CE_PANIC" .It Sy CE_CONT Used to continue another message or to display an informative message not associated with an error. Note that multiple .Sy CE_CONT messages without a newline may or may not appear on the system console or in the system log as a single line message. A single line message may be produced by constructing the message with .Xr sprintf 9F or .Xr vsprintf 9F before calling .Fn cmn_err . .It Sy CE_NOTE Used to display a message preceded with .Sy NOTICE . This message is used to report system events that do not necessarily require user action, but may interest the system administrator. For example, a message saying that a sector on a disk needs to be accessed repeatedly before it can be accessed correctly might be noteworthy. .It Sy CE_WARN Used to display a message preceded with .Sy WARNING . This message is used to report system events that require immediate attention, such as those where if an action is not taken, the system may panic. For example, when a peripheral device does not initialize correctly, this level should be used. .It Sy CE_PANIC Used to display a message preceded with .Qq Sy panic , and to panic the system. Drivers should specify this level only under the most severe conditions or when debugging a driver. A valid use of this level is when the system cannot continue to function. If the error is recoverable, or not essential to continued system operation, do not panic the system. .El .Pp The .Fa format is identical to the one described in .Xr sprintf 9F with additional meaning of the first character affecting where the message will be written: .Bl -tag -width Ds .It \&! The message goes only to the system log. .It Sy ^ The message goes only to the console. .It \&? If .Fa level is also .Sy CE_CONT , the message is always sent to the system log, but is only written to the console when the system has been booted in verbose mode. See .Xr kernel 1M . If neither condition is met, the .Qq Sy \&? character has no effect and is simply ignored. .El .Pp Refer to .Xr syslogd 1M to determine where the system log is written. .Pp The .Fn cmn_err function sends log messages to the log of the global zone. .Fn cmn_err appends a .Sy \en to each .Fa format , except when .Fa level is .Sy CE_CONT . .Ss Fn dev_err With the exception of its first argument .Pq Fa dip , .Fn dev_err is identical to .Fn cmn_err . .Fa dip is a pointer to a device's .Ft dev_info structure, which is used to prepend the driver name and instance number to the message. The driver name and instance number are retrieved using .Xr ddi_driver_name 9F and .Xr ddi_get_instance 9F . .Ss Fn vcmn_err The .Fn vcmn_err function is identical to .Fn cmn_err except that its last argument, .Fa ap , is a pointer to a variable list of arguments. .Fa ap contains the list of arguments used by the conversion specifications in .Fa format . .Fa ap must be initialized by calling .Xr va_start 9F . .Xr va_end 9F is used to clean up and must be called after each traversal of the list. Multiple traversals of the argument list, each bracketed by .Xr va_start 9F and .Xr va_end 9F , are possible. .Ss Fn zcmn_err With the exception of its first argument .Pq Fa zoneid , .Fn zcmn_err is identical to .Fn cmn_err . .Fa zoneid is the numeric ID of the zone to which the message should be directed. Note that .Fa zoneid only has an effect if the message is sent to the system log. Using .Fa zoneid will cause messages to be sent to the log associated with the specified local zone rather than the log in the global zone. This is accomplished by the message being received and processed by the .Xr syslogd 1M process running in the specified zone instead of the one running in the global zone. You can retrieve a process zone ID from its credential structure using .Xr crgetzoneid 9F . .Ss Fn vzcmn_err With the exception of its first argument .Pq Fa zoneid , .Fn vzcmn_err is identical to .Fn vcmn_err . See the description of .Fn zcmn_err above for an explanation on how the .Fa zoneid argument is handled. .Sh CONTEXT The .Fn cmn_err function can be called from user, kernel, interrupt, or high-level interrupt context. .Sh RETURN VALUES None. However, if an unknown .Fa level is passed to .Fn cmn_err , the following panic error message is displayed: .Bd -literal panic: unknown level in cmn_err (level=level, msg=format) .Ed .Sh EXAMPLES .Bl -tag -width Ds .It Sy Example 1 No Using Fn cmn_err This first example shows how .Fn cmn_err can record tracing and debugging information only in the system log .Pq lines 17 ; display problems with a device only on the system console .Pq line 23 ; or display problems with the device on both the system console and in the system log .Pq line 28 . .Bd -literal 1 struct reg { 2 uchar_t data; 3 uchar_t csr; 4 }; 5 6 struct xxstate { 7 ... 8 dev_info_t *dip; 9 struct reg *regp; 10 ... 11 }; 12 13 dev_t dev; 14 struct xxstate *xsp; 15 ... 16 #ifdef DEBUG /* in debugging mode, log function call */ 17 cmn_err(CE_CONT, "!%s%d: xxopen function called.", 18 ddi_binding_name(xsp->dip), getminor(dev)); 19 #endif /* end DEBUG */ 20 ... 21 /* display device power failure on system console */ 22 if ((xsp->regp->csr & POWER) == OFF) 23 cmn_err(CE_NOTE, "^OFF.", 24 ddi_binding_name(xsp->dip), getminor(dev)); 25 ... 26 /* display warning if device has bad VTOC */ 27 if (xsp->regp->csr & BADVTOC) 28 cmn_err(CE_WARN, "%s%d: xxopen: Bad VTOC.", 29 ddi_binding_name(xsp->dip), getminor(dev)); .Ed .It Sy Example 2 No Using the %b conversion specification This example shows how to use the .Sy %b conversion specification. Because of the leading .Qq Sy \&? character in the format string, this message will always be logged, but it will only be displayed when the kernel is booted in verbose mode. .Bd -literal cmn_err(CE_CONT, "?reg=0x%b\en", regval, "\e020\e3Intr\e2Err\e1Enable"); .Ed .It Sy Example 3 No Using Fa regval When .Fa regval is set to .Pq decimal 13, the following message would be displayed: .Bd -literal reg=0xd .Ed .It Sy Example 4 No Error Routine This example shows an error reporting routine which accepts a variable number of arguments and displays a single line error message both in the system log and on the system console. Note the use of .Fn vsprintf to construct the error message before calling .Fn cmn_err . .Bd -literal #include #include #include #define MAX_MSG 256; void xxerror(dev_info_t *dip, int level, const char *fmt, ...) { va_list ap; int instance; char buf[MAX_MSG], *name; instance = ddi_get_instance(dip); name = ddi_binding_name(dip); /* format buf using fmt and arguments contained in ap */ va_start(ap, fmt); vsprintf(buf, fmt, ap); va_end(ap); /* pass formatted string to cmn_err(9F) */ cmn_err(level, "%s%d: %s", name, instance, buf); } .Ed .It Sy Example 5 No Log to Current Zone This example shows how messages can be sent to the log of the zone in which a thread is currently running, when applicable. Note that most hardware-related messages should instead be sent to the global zone using .Fn cmn_err . .Bd -literal zcmn_err(crgetzoneid(ddi_get_cred()), CE_NOTE, "out of processes"); .Ed .El .Sh SEE ALSO .Xr dmesg 1M , .Xr kernel 1M , .Xr zones 5 , .Xr ddi_binding_name 9F , .Xr ddi_cred 9F , .Xr ddi_driver_name 9F , .Xr ddi_get_instance 9F , .Xr sprintf 9F , .Xr va_arg 9F , .Xr va_end 9F , .Xr va_start 9F .Pp Writing Device Drivers .Sh WARNINGS The .Fn cmn_err function with the .Sy CE_CONT argument can be used by driver developers as a driver code debugging tool. However, using .Fn cmn_err in this capacity can change system timing characteristics. .Sh NOTES Messages of arbitrary length can be generated using .Fn cmn_err , but if the call to .Fn cmn_err is made from high-level interrupt context and insufficient memory is available to create a buffer of the specified size, the message will be truncated to LOG_MSGSIZE bytes .Pq see Pa sys/log.h . For this reason, callers of .Fn cmn_err that require complete and accurate message generation should post down from high-level interrupt context before calling .Fn cmn_err .