Register Model
e200z3 Power Architecture Core Reference Manual, Rev. 2
Freescale Semiconductor
2-61
2.14
Branch Target Buffer (BTB) Registers
This section describes the only register that controls the branch target buffer.
2.14.1
Branch Unit Control and Status Register (BUCSR)
BUCSR, shown in
, is for general control and status of the branch target buffer (BTB).
BUCSR fields are described in
.
2.15
L1 Cache Configuration Registers
This section describes the register that helps not to configure the cache.
2.15.1
L1 Cache Configuration Register 0 (L1CFG0)
The L1 cache configuration register 0 (L1CFG0) provides information on how not to configure the e200z3
cache design. For e200z3, reads of this register return a value of all zeros.
32
53
54
55
62
63
Field
—
BBFI —
BPEN
Reset
All zeros
R/W
R/W
SPR
SPR 1013
Figure 2-42. Branch Unit Control and Status Register (BUCSR)
Table 2-27. Branch Unit Control and Status Register
Bits
Name
Description
32–53
—
Reserved, should be cleared.
54
BBFI
Branch target buffer flash invalidate. When set, BBFI flash clears the valid bit of all BTB entries; clearing
occurs regardless of the value of the enable bit (BPEN).
Note
: BBFI is always read as 0.
55–62
—
Reserved, should be cleared.
63
BPEN Branch target buffer (BTB) enable.
0 BTB prediction disabled. No hits are generated from the BTB and no new entries are allocated. Entries are
not automatically invalidated when BPEN is cleared; BBFI controls entry invalidation.
1 BTB prediction enabled (enables BTB to predict branches).
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