Compaq 21264, EV67 specifications Mbox Control Register Mctl, For, Acv

Models: 21264 EV67

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Mbox IPRs

Table 5–18 Memory Management Status Register Fields Description (Continued)

Name

Extent

Type

Description

 

 

 

 

FOR

[2]

RO

This bit is set when a fault-on-read error occurs during a read

 

 

 

transaction and PTE[FOR] was set.

ACV

[1]

RO

This bit is set when an access violation occurs during a transac-

 

 

 

tion. Access violations include a bad virtual address.

WR

[0]

RO

This bit is set when an error occurs during a write transaction.

 

 

 

 

Note: The Ra field of the instruction that triggered the error can be obtained from the Ibox EXC_SUM register.

5.3.9 Mbox Control Register – M_CTL

The Mbox control register (M_CTL) is a write-only register. Its contents are cleared by chip reset. Figure 5–32shows the Mbox control register.

Figure 5–32 Mbox Control Register

63

6

5

4

3

1

0

 

 

 

 

 

 

 

SMC[1:0]

SPE[2:0]

LK99-0040A

Alpha 21264/EV67 Hardware Reference Manual

Internal Processor Registers 5–29

Page 171
Image 171
Compaq 21264, EV67 specifications Mbox Control Register Mctl, For, Acv