Agilex™ 7 Hard Processor System Technical Reference Manual
Visible to Intel only — GUID: bxq1481129241476
Ixiasoft
Visible to Intel only — GUID: bxq1481129241476
Ixiasoft
3.5.12. Cache Protection
The L1 instruction cache provides parity checking with single error detection (SED). Double bit errors are not detected or corrected.
The L1 data cache and L2 cache provide single error correction and double error detection (SECDED). If a single-bit error is detected, the access that caused the error is stalled while the correction takes place. After correction, the access that was stalled continues or is retried.
RAM | Protection Type | Protection Granule | Correction Behavior |
---|---|---|---|
L1 Instruction cache tag | Parity, SED | 31 bits | Both lines in the cache set are invalidated, and then the line requested is refetched from L2 cache or external memory. |
L1 Instruction cache data | Parity, SED | 20 bits | Both lines in the cache set are invalidated, and then the line requested is refetched from L2 cache or external memory. |
TLB | Parity, SED | 52 bits | The entry is invalidated, and a new pagewalk is started to refetch it. |
L1 Data cache tag | Parity, SED | 32 bits | The line is cleaned and invalidated from the L1 cache. SCU duplicate tags are used to get the correct address. The line is refetched from L2 cache or external memory. |
L1 Data cache data | ECC, SECDED | 32 bits | The line is cleaned and invalidated from the L1 cache, with single bit errors corrected as part of the eviction. The line is refetched from L2 cache or external memory. |
L1 data cache dirty bit | Parity, SED with correction by re-loading data | 1 bit | The line is cleaned and invalidated from the L1 cache, with detection of dirty bit corruption through parity checking. Only the dirty bit is protected. The other bits are performance hints, therefore do not cause a functional failure if they are incorrect. Error is corrected by reloading the data. |
SCU L1 duplicate tag | ECC, SECDED | 33 bits | The tag is rewritten with the correct value, and the access is retried. If the error is uncorrectable then the tag is invalidated. |
L2 tag | ECC, SECDED | 33 bits | The tag is rewritten with the correct value, and the access is retried. If the error is uncorrectable then the tag is invalidated. |
L2 data | ECC, SECDED | 64 bits | Data is corrected inline, and the access might stall for an additional cycle or two while the correction takes place. After correction, the line might be evicted from the processor. |