Errors
Table 6-2.
Link Errors in Normal Operation (Sheet 2 of 2)
Error
Response
Access to unimplemented register
If UNIMPLCFG error type enabled in EMASK Register
1.
2.
3.
Drop Config Write cmds
Capture Addr in RECCFG register if not previously set
Return 0’s data if Config Read (or return -1 if Read addr to unimplemented
function - though currently expect all functions to be used)
UNIMPLCFG error type logged in FERR or NERR registers
Error/Alert Asserted bit set in FBD Status 0 register
4.
5.
Else ignore error
NOTE: The timing of the Error/Alert Asserted bit in FBD Status 0 response for an
unimplemented register is not guaranteed relative to the corresponding Sync/Status
boundaries. For example, if an unimplemented register access occurs in the frame
before a Sync frame, the Error Asserted bit in FBD Status 0 may not be asserted in
northbound Status corresponding to that Sync. But it will be asserted in a later
Status response.
Undefined command
Undefined commands with good CRC are ignored. This is not considered an error
condition, and is not logged. Treat as reserved command or Channel NOP
TID error on config writes
If the TID bit on a config write matches the value of the previous TID bit, the write
is ignored. The TID bit stored in the AMB is left unchanged in this case.
This error does not cause an alert frame, and is not logged.
The purpose of the TID bit is to allow the host to retry a config write command
following a fast reset if it does not know if it had been executed prior to an alert. If
the config write had occurred the TID bit will be the same, the retried write will be
ignored. If it had not occurred, the TID bit will be opposite, and the retried write to
will be executed.
6.1.2
DDR Errors
Table 6-3.
DDR Errors
Error
Response
Failure of software to achieve calibration
DDR voltage does not power up
This is detected through firmware during the calibration routine.
Firmware should treat the DIMM as a repeater if it is an intermediate DIMM or map
it out if it is the last DIMM in the chain
if normal FBD interface comes up, should at least act like a repeater. Does not bring
down FBD channel - like above. DDR cmds directed at DIMM will fail to return valid
responses.
6.1.3
Host Protocol Errors
AMBs are not expected to detect bad protocol from the host.
Table 6-4.
Host Protocol Errors
Error
Response
Illegal combinations of commands
AMB response to illegal command combinations is undefined
•
see Concurrent Command Delivery
Rules section of the FBD Architecture
and Protocol Specification
Commands to multiple AMBs to return
data in the same return frame.
If multiple AMBs attempt to return data in the same frame, the host will see the
data from the northern most AMB which is providing data, as it will replace any data
sent from AMBs to its south. A host controller should not produce commands which
would cause multiple AMBs to respond with data in the same frame. A special case
can occur where Alert frames are being sent by one or more AMBs while another
AMB is returning data from a command. These cases are discussed in the
Architecture and Protocol spec in the Northbound Alert Frame section.
Intel® 6400/6402 Advanced Memory Buffer Datasheet
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INTEL [ INTEL ]
