AMD-761 Datasheet, PDF (74/264 Pages) Advanced Micro Devices – AMD-761-TM System Controller Software/BIOS Design Guide

Preliminary Information
AMD-761™ System Controller Software/BIOS Design Guide
24081D—February 2002
Bit Definitions
Bit Name
31 Prb_En
30
29
28
27–25
Reserved
Reserved
Reserved
Xca_Prb_Cnt
24–22 Xca_RD_Cnt
21–19 Xca_WR_Cnt
18 Halt_Discon_En
17 Stp_Grant_
Discon_En
16–14 Prb_Limit
13–10 Ack_Limit
Function
Probe Enable
0 = Probes are not sent to this processor.
BIU0 Status/Control (Dev0:F0:0x60)
1 = Probes are sent to this processor.
This bit must be programmed to zero for normal operation.
This bit must be programmed to zero for normal operation.
This bit must be programmed to zero for normal operation.
Xca Probe Count
This bit field represents the maximum number of consecutive AMD Athlon™ processor
system bus grants for probe data movement types that are allowed before letting another
type have the bus.BIOS must program this field to a non-zero value for proper operation.
The recommended value to be loaded in this field by BIOS software is 0x2.
Xca Read Count
This bit field represents the maximum number of consecutive AMD Athlon processor
system bus grants for read data movement types that are allowed before letting another
type have the bus.BIOS must program this field to a non-zero value for proper operation.
The recommended value to be loaded in this field by BIOS software is 0x6.
Xca Write Count
This bit field represents the maximum number of consecutive AMD Athlon processor
system bus grants for write data movement types that are allowed before letting another
type have the bus.BIOS must program this field to a non-zero value for proper operation.
The recommended value to be loaded in this field by BIOS software is 0x6.
Halt Disconnect Enable
0 = No AMD Athlon system bus disconnect is performed following HALT.
1 = AMD Athlon system bus disconnects after receiving a HALT special cycle.
Stop Grant Disconnect Enable
0 = No AMD Athlon processor system bus disconnect is performed following STOP/GRANT.
1 = AMD Athlon processor system bus disconnects after receiving a STOP/GRANT special cycle.
Probe Limit
BIOS software initializes this field with the maximum number of outstanding probes that
the given CPU can handle. The default is a single probe. Encoding is as follows:
0b000 = 1 probe
0b001 = 2 probes
................................
0b111 = 8 probes
Ack Limit
BIOS software reads this field to determine how many outstanding unacknowledged
AMD Athlon processor system bus commands can be sent to the AMD-761™ system
controller. The AMD-761 system controller allows a maximum of four unacknowledged
commands. Encoding is as follows:
0b0000 = 1 unacknowledged command
0b0001 = 2 unacknowledged commands
..........................................................
0b1111 = 16 unacknowledged commands
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AMD-761™ System Controller Programmer’s Interface
Chapter 2