Compaq 21264, EV67 specifications Interrupt Summary Register Isum

Models: 21264 EV67

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Ibox IPRs

Figure 5–17 Software Interrupt Request Register

63

29 28

14 13

0

 

 

 

 

 

 

SIR[15:1]

LK99-0023A

Table 5–6describes the software interrupt request register fields.

Table 5–6 Software Interrupt Request Register Fields Description

Name

Extent

Type

Description

 

 

 

 

Reserved

[63:29]

SIR[15:1]

[28:14]

RW

Software Interrupt Requests

Reserved

[13:0]

 

 

 

 

5.2.11 Interrupt Summary Register – ISUM

The interrupt summary register (ISUM) is a read-only register that records all pending hardware, software, and AST interrupt requests that have their corresponding enable bit set.

If a new interrupt (hardware, serial line, crd, or performance counters) occurs simulta- neously with an ISUM read, the ISUM read returns zeros. That condition is normally assumed to be a passive release condition. The interrupt is signaled again when the PALcode returns to native mode. The effects of this condition can be minimized by reading ISUM twice and ORing the results.

Usage of ISUM in performance monitoring is described in Section 6.10. Figure 5–18shows the interrupt summary register.

Figure 5–18 Interrupt Summary Register

63

39 38

33 32 31 30 29 28

14 13

11 10 9

8

5

4

3

2

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EI[5:0]

SL

CR

PC[1:0]

SI[15:1]

ASTU

ASTS

ASTE

ASTK

LK99-0024A

Alpha 21264/EV67 Hardware Reference Manual

Internal Processor Registers 5–11

Page 153
Image 153
Compaq 21264, EV67 specifications Interrupt Summary Register Isum, 6describes the software interrupt request register fields