Solaris DDI specific (Solaris DDI)

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.

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.

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;
    }
    ...
}

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

ddi_check_acc_handle(9F), ddi_check_dma_handle(9F), ddi_get_devstate(9F)