Sun Microelectronics
184
UltraSPARC User’s Manual
11.3.4 UltraSPARC Data Buffer (UDB) Error Register
For implementation efficiency, the UltraSPARC Data Buffer (UDB) error and con-
trol registers are physically separated into upper half and lower half registers.
Separate ASIs are used for reading (7F
16
) and writing (77
16
) the UDB registers.
Software should check the status of each register when an ECC error is reported.
If software attempts to clear these bits at the same time that an error occurs, the
appropriate error bit will be set to avoid losing error information.
Name
: ASI_UDBH_ERROR_REG_WRITE
ASI=77
16
, VA<63:0>=0
16
Name
: ASI_UDBH_ERROR_REG_READ
ASI=7F
16
, VA<63:0>=0
16
Name
: ASI_UDBL_ERROR_REG_WRITE
ASI=77
16
, VA<63:0>=18
16
Name
: ASI_UDBL_ERROR_REG_READ
ASI=7F
16
, VA<63:0>=18
16
E_SYNDR
: ECC syndrome for correctable errors from system. In case of multiple
outstanding errors, only the first is recorded.
Bits <9:8> are sticky error bits that record the most recently detected errors. These
bits accumulate errors that have been detected since the last write to clear to this
register. The UDB error registers are not cleared automatically during a read.
Writes to this register with bits eight or nine set will clear the corresponding bits
in the error register. Writes to the error register with particular bits clear will not
affect the corresponding bits in the error register. The syndrome field is read only
and writes to this field are ignored.
Note:
A recorded correctable error may be overwritten by an uncorrectable
error.
Table 11-7
UDB Error Register Format
Bits
Field
Use
RW
<63:10>
Reserved
—
R
<9>
UE
If set, UE has occurred
RW
<8>
CE
If set, CE has occurred
RW
<7:0>
E_SYNDR
ECC syndrome from system
R
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