AMD AMD-K6-2/400 User Guide - Page 288

L2 Cache Data Reads, L2 Tag or Data Location for the AMD-K6™-2E+ Processor-EDX

Page 288 highlights

Preliminary Information AMD-K6™-2E+ Embedded Processor Data Sheet 23542A/0-September 2000 page 266 describes the operation that is performed based on the instruction and the T/D bit. Symbol Description T/D Selects Tag (1) or Data (0) access Way Selects desired cache way Bit 20 17-16 31 21 20 19 18 17 16 15 14 T / Way D Reserved Symbol Description Bit Set Selects the desired cache set 14-6 Line Selects Line1 (1) or Line0 (0) 5 Octet Selects one of four octets 4-3 Dword Selects upper (1) or lower (0) dword 2 6 5 4 32 1 0 L D Set i n e Octet w o r d Figure 93. L2 Tag or Data Location for the AMD-K6™-2E+ Processor-EDX L2 Cache Data Reads Table 53. Tag versus Data Selector Instruction T/D (EDX[20]) Operation RDMSR 0 Read dword from L2 data array into EAX. Dword location is specified by EDX. RDMSR 1 Read tag, line state and LRU information from L2 tag array into EAX. Location of tag is specified by EDX. WRMSR 0 Write dword to the L2 data array using data in EAX. Dword location is specified by EDX. WRMSR 1 Write tag, line state and LRU information into L2 tag array from EAX. Location of tag is specified by EDX. When the L2AAR is read or written, EDX is left unchanged. This facilitates multiple accesses when testing the entire cache/tag array. If the L2 cache data is read (as opposed to reading the tag information), the result (dword) is placed in EAX in the format 266 Test and Debug Chapter 13

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266
Test and Debug
Chapter 13
AMD-K6™-2E+ Embedded Processor Data Sheet
23542A/0—September 2000
Preliminary Information
page 266 describes the operation that is performed based on
the instruction and the T/D bit.
Figure 93.
L2 Tag or Data Location for the AMD-K6™-2E+ Processor—EDX
When the L2AAR is read or written, EDX is left unchanged.
This facilitates multiple accesses when testing the entire
cache/tag array.
L2 Cache Data Reads
If the L2 cache
data
is read (as opposed to reading the tag
information), the result (dword) is placed in EAX in the format
Reserved
0
Set
21
31
20 19
17
16
5
15
18
Way
4
3
2
1
6
Symbol
Description
Bit
Set
Selects the desired cache set
14-6
Line
Selects Line1 (1) or Line0 (0)
5
Octet
Selects one of four octets
4-3
Dword
Selects upper (1) or lower (0) dword
2
L
i
n
e
Octet
D
w
o
r
d
T
/
D
Symbol
Description
Bit
T/D
Selects Tag (1) or Data (0) access
20
Way
Selects desired cache way
17-16
14
Table 53.
Tag versus Data Selector
Instruction
T/D
(EDX[20])
Operation
RDMSR
0
Read dword from L2 data array into EAX. Dword location
is specified by EDX.
RDMSR
1
Read tag, line state and LRU information from L2 tag array
into EAX. Location of tag is specified by EDX.
WRMSR
0
Write dword to the L2 data array using data in EAX. Dword
location is specified by EDX.
WRMSR
1
Write tag, line state and LRU information into L2 tag array
from EAX. Location of tag is specified by EDX.