Sun Microelectronics
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UltraSPARC User’s Manual
7.17.2.4 Physical Address PA<40:4>
Bits PA<40:4> of the 41-bit physical address space accessible to UltraSPARC.
The low order 4 bits PA<3:0> of the physical address are implied in the bytemask
in P_NCRD_REQ and P_NCWR_REQ transactions. All other transactions transfer
64-byte blocks and thus, PA<3:0>=0.
7.17.2.5 Bytemask<15:0>
Bytemask, used only in P_NCRD_REQ and P_NCWR_REQ. This 16-bit field indi-
cates valid bytes on SYSDATA.
The bytemask indicates 1-, 2-, 4-, 8- and 16-byte noncached read requests to Inter-
connect slave ports. Arbitrary bytemasks are allowed for slave writes, including a
bytemask of all zeros to indicate a no-op at the slave.
Bytemask<0> corresponds to byte 0 (bits <127:120> on SYSDATA).
7.17.2.6 DVP
Dirty Victim Pending writeback bit. This bit is set when a coherent read victim-
ized a dirty line. The system uses this bit for victim handling.
7.17.2.7 IVA
Invalidate me Advisory bit (in P_WRI_REQ transaction only). UltraSPARC sets
this bit if it wants SC to send an S_INV_REQ back to it. SC ignores this bit in sys-
tems that support Dtags.
7.17.2.8 NDP
No Duplicate tag Present Bit. SC sets this bit S_REQ packets only; it is zero in
non-coherent P_REQ slave requests. SC sets NDP in systems that do not track the
E-Cache contents; that is, if the coherent request is for a line that may not be in
the E-Cache or writeback buffer. This bit is zero in systems that track the E-Cache
contents.
If NDP=1, UltraSPARC issues replies to copyback requests with P_SNACK if it
does not have the requested block. If NDP=0, UltraSPARC issues P_SACK if it
does not have the requested block. Actually, when NDP=0, UltraSPARC does not
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