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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—Error Handling
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
952
Order Number: 306262-004US
28.2
Responses to Errors
Most memories internal or external to the IXP45X/IXP46X network processors have
some variety of data corruption detection capability. The only significant exception to
this rule is the buffer memory of the USB device controller. The Expansion Bus, AQM,
and MCU (a.k.a DDRI SDRAM Controller) will all send interrupt signals directly to the
interrupt controller indicating data corruption detected by those units. The NPEs will
halt as a result of internal data corruption, which will in turn send interrupt signals.
The interrupt unit has a special mechanism which will allow software to set these sorts
of interruptions as highest priority interruptions.
28.2.1
PCI Responses to Errors
The PCI Unit will interpret AHB Error as AHB Retry. As a result, it will most likely retry
the errored transaction. In the event that the error was caused by a one-time transient
condition, this retry will receive good data the second time, and continue operating
normally. In the event that this is a continuing system issue, the PCI unit will not
receive a valid data response, and will continue this retry until either the condition is
repaired or the PCI unit is reset.
In the event of such an error, although the PCI responds as if a retry had occurred, the
unit which asserted AHB error will be sending an interrupt to the Interrupt Controller.
This allows the Intel XScale processor to know that an error condition exists, and
attempt to solve in whatever manner determined appropriate for the given system.
External PCI errors will not be reflected back on the AHB bus.
28.2.2
NPE Responses to Errors
There are three types of NPE soft errors
• NPE IMEM Parity error
• NPE DMEM Parity error
• NPE Coprocessor errors
Multiple concurrent error handling and recovery is not supported in the IXP45X/IXP46X
network processors. There are two types of NPE Coprocessor errors:
• AHB error
• Switching Coprocessor error
AHB error is valid on all the NPEs. The causes of AHB error include:
• AHB Slave access error
• Read/Write to an invalid AHB address access
• An illegal transfer size access on the AHB Bus.
The AHB Slave access error can be caused by one of four sources:
• an uncorrectable ECC error on DDRI read access
• parity error on a Queue Manager read Access
• a parity error from an Expansion Bus read access
• an error during a PCI unit access
Refer to the PCI unit specification for the cause of errors during a PCI unit access. The
Switching Coprocessor Parity error is valid ONLY for NPE B and is asserted when there
is a parity error in Switching coprocessor content addressable memory.