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SPARC JPS1 Implementation Supplement:
Fujitsu SPARC64 V
• Release 1.0, 1 July 2002
P.9.4 Handling of a U2 Cache Data Error
U2 cache data is protected by 2-bit error detection and 1-bit error correction ECC,
attached to every doubleword.
Correctable Error in U2 Cache Data
When a correctable error is detected in the incoming U2 cache fill data from UPA, the
data is corrected by hardware, stored into U2 cache, and the restrainable error
ASI_AFSR.CE_INCOMED
is detected.
When a correctable error is detected in the data from U2 cache for I1 cache fill, D1
cache fill, copyback to UPA, or writeback to UPA, both the transfer data and source
data in U2 cache are corrected by hardware. The error is not reported to software.
Marked Uncorrectable Error in U2 Cache Data
For U2 cache data, a doubleword with marked
UE
is treated the same as a correct
doubleword. No error is reported when the marked
UE
in U2 cache data is detected.
When a marked uncorrectable error (
UE
) is detected in incoming U2 cache fill data
from UPA, the doubleword with the marked UE is stored without modification in
the target U2 cache line.
When a marked uncorrectable error is detected in incoming data from the D1 cache
to writeback D1 cache line, the doubleword with the marked
UE
is stored without
modification in the target U2 cache line. Note that there is no raw
UE
in D1 writeback
data because error marking is applied for D1 writeback data, as described in
Handling of a D1 Cache Data Error
on page 190.
When a marked
UE
is detected in the data read from the U2 cache for an I1 cache fill,
D1 cache fill, copyback to UPA, or writeback to UPA, the doubleword with the
marked
UE
is transferred without modification.
Raw Uncorrectable Error in U2 Cache Data
When a raw (unmarked)
UE
is detected in incoming U2 cache fill data from UPA,
error marking is applied for the doubleword with the raw
UE
,
using
ERROR_MARK_ID
= 0. The doubleword and its ECC are changed to the marked
UE
data, the changed data is stored into target U2 cache line, and the restrainable error
ASI_AFSR.UE_RAW_L2$FILL
is detected.
When a raw
UE
is detected in data read from U2 cache, such as for I1 cache fill, D1
cache fill, copyback to UPA, or writeback to UPA, then error marking is applied for
the doubleword with the raw
UE
, using
ERROR_MARK_ID
=
ASI_EIDR
. Both the