Sun Microelectronics
96
UltraSPARC User’s Manual
6.
SC should cancel a P_WRB_REQ transaction when a P_RDO_REQ
(S_CPI_REQ to UltraSPARC) or P_WRI_REQ (S_INV_REQ to UltraSPARC)
from any other UltraSPARC invalidates the Writeback line.
7.
UltraSPARC will not issue a read request for a line that is already in its
cache (this includes P_RDD_REQ).
Figure 7-20 on page 95 shows that some transitions are caused by the
PREFETCH{A} instructions, which are not supported by all UltraSPARC models.
Table 7-8 shows which UltraSPARC models support the PREFETCH{A} instruc-
tions.
Table 7-8
PREFETCH{A} Instruction Support
UltraSPARC-I
UltraSPARC-II
PREFETCH{A}
✓
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