Sun Microsystems UltraSPARC-I - Page 145

Sun Microelectronics
130
UltraSPARC User’s Manual
Table 7-23 and Table 7-24, respectively specify the legal request/reply combina-
tions for UltraSPARC and the SC.
1.
UltraSPARC-I supports only one outstanding writeback transaction. The writeback and its concomitant dirty victim
read transaction must both complete before a second writeback or a second dirty victim read is issued. UltraSPARC-II
supports two outstanding writeback transactions.
2.
There is no data transfer for these S_REPLY types.
1.
UltraSPARC can generate P_FERR at any time, even if there is no outstanding system transaction; it should cause SC
to generate a system wide Power-on Reset.UltraSPARC asserts P_FERR when it detects a parity error on the request
packet or the E-Cache tags. There is no data transfer.
2.
SC issues S_REPLY only if there is no error and data is to be transferred to/from UltraSPARC.
Table 7-23 Valid Request and Reply Types—UltraSPARC to SC
UltraSPARC Request Reply from SC
P_RDS_REQ S_RBU or S_RBS or S_ERR
2
or S_RTO
2
P_RDSA_REQ S_RBS or S_ERR
2
or S_RTO
2
P_RDO_REQ S_OAK
2
or S_RBU or S_ERR
2
or S_RTO
2
P_RDD_REQ S_RBS or S_ERR
2
or S_RTO
2
P_WRB_REQ
1
S_WAB or S_WBCAN
2
P_WRI_REQ S_WAB
P_NCBWR_REQ S_WAB
P_NCWR_REQ S_WAS
P_NCBRD_REQ S_RBU or S_ERR
2
or S_RTO
2
P_NCRD_REQ S_RAS or S_ERR
2
or S_RTO
2
P_INT_REQ S_WAB or S_INAK
2
Table 7-24 Valid Request and Reply Types—SC to UltraSPARC
SC Request P_REPLY from UltraSPARC S_REPLY from SC
2
S_INV_REQ P_SACK or P_SACKD or P_SNACK or P_FERR
1
None
S_CPB_REQ P_SACK or P_SACKD or P_SNACK or P_FERR
1
S_CRAB
S_CPD_REQ P_SACK or P_SACKD or P_SNACK or P_FERR
1
S_CRAB
S_CPI_REQ P_SACK or P_SACKD or P_SNACK or P_FERR
1
S_CRAB
P_NCRD_REQ P_RAS or P_FERR
1
S_SRS
P_INT_REQ P_IAK or P_FERR
1
S_SWIB
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