illumos: manual page: ddi_dev_report

DDI_DEV_REPORT_FAULT(9F) Kernel Functions for Drivers DDI_DEV_REPORT_FAULT(9F)

NAME

ddi_dev_report_fault - Report a hardware failure

SYNOPSIS

#include <sys/ddi.h>
#include <sys/sunddi.h>

void ddi_dev_report_fault (dev_info_t *dip,
ddi_fault_impact_t impact, ddi_fault_location_t location,
const char *message );

INTERFACE LEVEL

illumos DDI specific (illumos DDI)

PARAMETERS

dip
Pointer to the driver's dev_info structure to which the
fault report relates. (Normally the caller's own dev_info
pointer).

impact
One of a set of enumerated values indicating the impact of
the fault on the device's ability to provide normal service.

location
One of a set of enumerated values indicating the location of
the fault, relative to the hardware controlled by the driver
specified by dip.

message
Text of the message describing the fault being reported.

DESCRIPTION

This function provides a standardized mechanism through which device
drivers can report hardware faults. Use of this reporting mechanism
enables systems equipped with a fault management system to respond to
faults discovered by a driver. On a suitably equipped system, this might
include automatic failover to an alternative device and/or scheduling
replacement of the faulty hardware.

The driver must indicate the impact of the fault being reported on its
ability to provide service by passing one of the following values for the
impact parameter:

DDI_SERVICE_LOST
Indicates a total loss of service. The driver
is unable to implement the normal functions of
its hardware.

DDI_SERVICE_DEGRADED
The driver is unable to provide normal service,
but can provide a partial or degraded level of
service. The driver may have to make repeated
attempts to perform an operation before it
succeeds, or it may be running at less than its
configured speed. A driver may use this value
to indicate that an alternative device should
be used if available, but that it can continue
operation if no alternative exists.

DDI_SERVICE_UNAFFECTED
The service provided by the device is currently
unaffected by the reported fault. This value
may be used to report recovered errors for
predictive failure analysis.

DDI_SERVICE_RESTORED
The driver has resumed normal service,
following a previous report that service was
lost or degraded. This message implies that
any previously reported fault condition no
longer exists.

The location parameter should be one of the following values:

DDI_DATAPATH_FAULT
The fault lies in the datapath between the driver
and the device. The device may be unplugged, or a
problem may exist in the bus on which the device
resides. This value is appropriate if the device
is not responding to accesses, (for example, the
device may not be present) or if a call to
ddi_check_acc_handle(9F) returns DDI_FAILURE.

DDI_DEVICE_FAULT
The fault lies in the device controlled by the
driver. This value is appropriate if the device
returns an error from a selftest function, or if
the driver is able to determine that device is
present and accessible, but is not functioning
correctly.

DDI_EXTERNAL_FAULT
The fault is external to the device. For example,
an Ethernet driver would use this value when
reporting a cable fault.

If a device returns detectably bad data during
normal operation (an "impossible" value in a
register or DMA status area, for example), the
driver should check the associated handle using
ddi_check_acc_handle(9F) or
ddi_check_dma_handle(9F) before reporting the
fault. If the fault is associated with the handle,
the driver should specify DDI_DATAPATH_FAULT
rather than DDI_DEVICE_FAULT. As a consequence of
this call, the device's state may be updated to
reflect the level of service currently available.
See ddi_get_devstate(9F).

Note that if a driver calls ddi_get_devstate(9F)
and discovers that its device is down, a fault
should not be reported- the device is down as the
result of a fault that has already been reported.
Additionally, a driver should avoid incurring or
reporting additional faults when the device is
already known to be unusable. The
ddi_dev_report_fault() call should only be used to
report hardware (device) problems and should not be
used to report purely software problems such as
memory (or other resource) exhaustion.

EXAMPLES

An Ethernet driver receives an error interrupt from its device if various
fault conditions occur. The driver must read an error status register to
determine the nature of the fault, and report it appropriately:

static int
xx_error_intr(xx_soft_state *ssp)
{
...
error_status = ddi_get32(ssp->handle, &ssp->regs->xx_err_status);
if (ddi_check_acc_handle(ssp->handle) != DDI_SUCCESS) {
ddi_dev_report_fault(ssp->dip, DDI_SERVICE_LOST,
DDI_DATAPATH_FAULT, "register access fault");
return DDI_INTR_UNCLAIMED;
}
if (ssp->error_status & XX_CABLE_FAULT) {
ddi_dev_report_fault(ssp->dip, DDI_SERVICE_LOST,
DDI_EXTERNAL_FAULT, "cable fault")
return DDI_INTR_CLAIMED;
}
if (ssp->error_status & XX_JABBER) {
ddi_dev_report_fault(ssp->dip, DDI_SERVICE_DEGRADED,
DDI_EXTERNAL_FAULT, "jabbering detected")
return DDI_INTR_CLAIMED;
}
...
}

CONTEXT

The ddi_dev_report_fault() function may be called from user, kernel, or
interrupt context.