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MPC106 PCIB/MC User's Manual
MOTOROLA
Table 3-37. Bit Settings for PICR2—0xAC
Bit
Name
Reset
Value
Description
31
L2_UPDATE_EN
0
L2 update enable. This bit controls whether the
internally-controlled L2 cache can be updated with new data.
Note that this bit has no effect on the external L2 cache
controller operation. Also, note that L2_UPDATE_EN is
accessible at port 0x81C.
0
The L2 cache can only be read or invalidated. The L2
cache cannot be updated. Snoops are serviced to
maintain coherency.
1
The L2 cache can be updated with new data.
30
L2_EN
0
This bit enables/disables the internally-controlled L2 cache.
The L2 cache is only enabled if both this bit and CF_L2_MP
signify that there is an internally-controlled L2 cache in the
system. Note that this bit has no effect on the external L2
cache controller operation. Also, note that L2_EN is
accessible at port 0x81C.
0
The L2 cache is disabled. However, the tags are not
invalidated. No L2 snoop operations or data updates are
performed while this bit is cleared.
1
The L2 cache is enabled.
29
NO_SERIAL_CFG
0
This bit controls whether the MPC106 serializes configuration
writes to PCI devices from the 60x bus.
0
Configuration writes to PCI devices from the 60x bus
cause the MPC106 to serialize and flush the internal
buffers.
1
Configuration writes to PCI devices from the 60x bus do
not cause serialization. The internal buffers are not
flushed.
28
CF_FLUSH_L2
0
L2 cache flush. The transition on this bit from 0 to 1 initiates
an internally-controlled L2 cache flush and invalidate
operation, provided L2_EN = 0b1. Note that this bit has no
effect on the external L2 cache controller operation. Also,
note that CF_FLUSH_L2 is accessible at port 0x81C.
0
Normal cache operation.
1
The transition from 0 to 1 indicates that the L2 cache
should write all modified lines to memory and mark all
lines as invalid.
27
NO_SNOOP_EN
0
This bit controls whether the MPC106 generates snoop
transactions on the 60x bus for PCI-to-system memory
transactions. This is provided as a performance enhancement
for systems that do not need to maintain coherency on
system memory accesses by PCI.
0
Snooping is enabled.
1
Snooping is disabled.