Fujitsu Fujitsu SPARC64 V Handling of a U2 Cache Data Error, Correctable Error in U2 Cache Data

ASI_AFSR.CE_INCOMED

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

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

192 SPARC JPS1 Implementation Supplement: Fujitsu SPARC64 V • Release 1.0, 1 July 2002