
MOTOROLA
Chapter 2. Register Model
2-13
Register Set
Table 2-6 shows how HID0[BCLK], HID0[ECLK], and core_hreset are used to configure
core_clk_out. See Section 8.3.15.2, “Test Clock Output (core_clk_out),” for more
information.
21
DCFI
Data cache flash invalidate
0 The data cache is not invalidated. The bit is cleared when the invalidation operation begins
(usually the next cycle after the write operation to the register). The data cache must be enabled
for the invalidation to occur.
1 An invalidate operation is issued that marks the state of each data cache block as invalid
without writing back modified cache blocks to memory. Cache access is blocked during this
time. Bus accesses to the cache are signaled as a miss during invalidate-all operations. Setting
DCFI clears all the valid bits of the blocks and the PLRU bits to point to way L0 of each set.
For the G2 core, the proper use of the ICFI and DCFI bits is to set and clear them with two
consecutive
mtspr
operations.
22–23
—
Reserved, should be cleared.
24
IFEM
Enable M bit on 60x bus for instruction fetches
0 M bit not reflected on bus for instruction fetches. Instruction fetches are treated as nonglobal
on the bus.
1 Instruction fetches reflect the M bit from the WIM settings
25–26
—
Reserved, should be cleared.
27
FBIOB
Force branch indirect on bus
0 Register indirect branch targets are fetched normally
1 Forces register indirect branch targets to be fetched externally
28
ABE
Address broadcast enable. Controls whether certain address-only operations (such as cache
operations) are broadcast on the 60x bus.
0 Address-only operations affect only local caches and are not broadcast
1 Address-only operations are broadcast on the 60x bus
Affected instructions are
dcbi
,
dcbf
, and
dcbst
. Note that these cache control instruction
broadcasts are not snooped by the G2 core. Refer to Section 4.3.3, “Data Cache Control,” for
more information.
29–30
—
Reserved, should be cleared.
31
NOOPTI
No-op the data cache touch instructions
0 The
dcbt
and
dcbtst
instructions are enabled
1 The
dcbt
and
dcbtst
instructions are no-oped globally
1
See Chapter 10, “Power Management.”
2
See Chapter 4, “Instruction and Data Cache Operation.”
Table 2-5. HID0 Bit Functions (continued)
Bits
Name
Function
F
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n
.