29 September 1997 – Subject To Change
Error Detection and Error Handling
8–5
Error Flows
•
CBOX_ADDR: Contains the physical address bits <39:04> of the octaword
associated with the error.
8.1.8 System Read Operations of the Bcache
The 21164PC does not check the parity on outgoing Bcache data. If it is bad, the
receiving processor will detect it.
8.1.9 Fill Timeout (FILL_ERROR_H)
•
For systems in which fill timeout can occur, the system environment should
detect fill timeout and cleanly terminate the reference to 21164PC. If the system
environment expects fill timeout to occur, it should detect them. If it does not
expect them (as might be true in small systems with fixed memory access tim-
ing), it is likely that the internal IDU timeout will eventually detect a stall if a fill
fails to occur. To properly terminate a fill in an error case, the fill_error_h pin is
asserted for one cycle and the normal fill sequence involving the fill_h,
fill_id_h, and dack_h pins is generated by the system environment.
•
A fill_error_h assertion forces a PALcode trap to the MCHK entry point, but
has no other effect.
Note:
No internal status is saved to show that this happened. If necessary, sys-
tems must save this status, and include read operations of the appropriate
status registers in the MCHK PALcode.
8.1.10 System Machine Check
•
The 21164PC has a maskable machine check interrupt input pin. It is used by
system environments to signal fatal errors that are not directly connected to a
read access from the 21164PC. It is masked at IPL 31 and anytime the 21164PC
is in PALmode.
•
ISR: <MCK> is set.
8.1.11 IDU Timeout
•
When the IDU detects a timeout, it causes a PALcode trap to the MCHK entry
point.
•
Simultaneously, a partial internal reset occurs: most states (except the IPR state)
are reset. This should not be depended on by systems in which fill timeouts
occur in typical use (such as, operating system or console code probing locations