Sable CPU Module Specification

Table 76: B-Cache Uncorrectable Errors
Copyright © 1993 Digital Equipment Corporation.
Transaction Causing
Probe Access Reason Error Recovery Activity
System-bus READ (Dirty)
or Exchange (Read Dirty)
System-bus READ / EX-
CHANGE Dirty
System-bus Write Probe If HIT System-bus write data
has either bad parity or has
CUCERR L
Assert System-bus CUCERR L with the data
returned to the System-bus.
The B-Cache Uncorrectable Error (BCUE) and
B-Cache Uncorrectable Error Address Registers
(BCUEA) are frozen and the UNCOR-
RECTABLE ERROR bit set.
The B-Cache is written with BAD EDC.
DECchip 21064 Read Block Victim Processing The System-bus C_ERR L signal is asserted,
the victim written to memory coincident with
the assertion of CUCERR L and the cycle is
acknowledged to the processor with HARD_
ERROR.
The B-Cache is not updated, and B-Cache allocation
is disabled.
The BCUE and BCUEA registers are frozen
and the UNCORRECTABLE ERROR bit set.
System-bus returned data
with bad System-bus parity
or
CUCERR L asserted with
read data
DECchip 21064 Write Block Victim Processing / Shared
Masked Write
The System-bus C_ERR L signal is asserted,
bad "second" read data from the System-bus
is returned to the processor, bad "second" data
from the System-bus is written with "bad EDC"
in the B-Cache,
The BCUE and BCUEA registers are frozen
and the UNCORRECTABLE ERROR bit set,
processor is acknowledged with HARD_ERROR.
The System-bus C_ERR L signal is asserted,
the victim / shared write is written to memory
coincident with the assertion of CUCERR L,
and the B-Cache is updated with the new data.
In the case of a shared masked write, the B-
Cache longwords with failing EDC that are not
updated by the processor write, will not be rewritten.
The BCUE and BCUEA registers are frozen
and the UNCORRECTABLE ERROR bit set.
Fault Management/Error Recovery 185