AMD Geode LX 800@0.9W - Manual (Page 163)

AMD Geode™ LX Processors Data Book 163
CPU Core Register Descriptions 33234H
5.5.2.65 Data Memory Subsystem Prefetch Lock MSR (DM_PFLOCK_MSR)
20 NOPFXEVCT No Prefetch Prefix Evictions. This bit disables clean line eviction in the case where a
new allocation occurs on a load/store miss when a move string operation uses the
REPNZ prefix instead of the normal REP prefix (restricted cache move feature, see PFX-
LOCK, bits [15:0]). When NOPFXEVCT is set, cache lines replaced by a load instruction
using the restricted cache prefix (REPNZ) will not be evicted if they are clean. (See EVC-
TONRPL bit description in DM_CONFIG0_MSR (MSR 00001800h[14]) for clean line
eviction feature). Clean line evictions of this type can be disabled in order to protect the
Victim mode L2 cache from being polluted by the transient data being moved. If this bit is
a 0, then normal clean line eviction occurs on any line replacement if enabled by the
EVCTONRPL bit. Note that any dirty line that is replaced will be evicted regardless of the
state of this bit. (Default = 0)
19:16 ARRAYDIS Array Disable. Mask used to disable individual cache arrays (way groups) in the DM to
save power or to avoid array defects. When an array is disabled, the DM will not read or
write the data array or tag array associated with this way group, reducing power. Any
data in the cache must be flushed before disabling an array or it will be lost.
Bit 19: Ways 15-12
Bit 18: Ways 11-8
Bit 17: Ways 7-4
Bit 16: Ways 3-0
0: Enable. (Default)
1: Disable.
15:0 PFXLOCK Prefetch Prefix Instructions Lock. Bit mask of ways that cannot be allocated or
replaced on a load miss when a move string operation uses the REPNZ prefix (instead of
the normal REP prefix). If all ways are locked, caching is effectively disabled, though the
cache will still be interrogated. Note that the REPNZ prefix has no effect on PREFETCH
instructions or writes to a write-allocate region that miss the cache and cause a write-
allocate. (Default = 0)
MSR Address 00001804h
Type R/W
Reset Value 00000000_00000000h
DM_CONFIG1_MSR Bit Descriptions (Continued)
Bits Name Description
DM_PFLOCK_MSR Register Map
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
PFLOCKT2 PFLOCKT1
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PFLOCKT0 PFLOCKNTA