User`s guide

The XMI
2.5.7 Disown Write Mask Transactions
The Disown Write Mask (DWMASK) transaction (see Figure 2–18) is used
with the Ownership Read transaction to implement the block ownership
writeback protocol. The OREAD and DWMASK commands are used by
the CPU nodes that contain writeback caches.
Figure 2–18 Disown Write Mask Command
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90
WRITE MASK ADDRESS<29:0>
LENGTH 00 = Hexword
10 = Quadword
11 = Octaword
msb−p191−89
0100 MBZ
ADDRESS<39:30>
DISOWN WRITE MASK COMMAND
When a CPU needs to free up a cache block that it owns, it uses a
DWMASK transaction to return the block to main memory. A successful
DWMASK transaction results in returning the block to the "free"
state. The XMI supports quadword, octaword, and hexword DWMASK
transactions.
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