5–12 Internal Processor Registers
Alpha 21264/EV67 Hardware Reference Manual
Ibox IPRs

Table 5–7 describes the interrupt summary register fields.

5.2.12 Hardware Interrupt Clear Register – HW_INT_CLR

The hardware interrupt clear register (HW_INT_ C LR) is a write-only register used to

clear edge-sensitive interrupt requests. See Section D.31 for more inf ormation abo ut the

PALcode restriction concerning this regis te r. Figure 5–19 shows the hardware interrupt

clear register.

Figure 5–19 Hardware Interrupt Clear Register
Table 5–7 Interrupt Summary Register Fields Description
Name Extent Type Description
Reserved [63:39] ——
EI[5:0] [38:33] RO External Interrupts
SL [32] RO Serial Line Interrupt
CR [31] RO Corrected Read Error Interrupts
PC[1:0] [30:29] RO Performance Counter Interrupts
PC0 when PC[0] is set.
PC1 when PC[1] is set.
SI[15:1] [28:14] RO Software Interrupt s
Reserved [13:11] —
ASTU, ASTS [10],[9] RO AST Interrupts
For each processor mode, the bit is set if an associated AST
interrupt is pending. This includes the mode’s ASTER and
ASTRR bits and whether the processor mode value held in the
IER_CM register is greater than or equal to the value for the
mode.
Reserved [8:5] —
ASTE, ASTK [4],[3] RO AST Interrupts
For each processor mode, the bit is set if an associated AST
interrupt is pending. This includes the mode’s ASTER and
ASTRR bits and whether the processor mode value held in the
IER_CM register is greater than or equal to the value for the
mode.
Reserved [2:0] —
63 292827 26 25333231 30 0
SL
CR
PC[1:0]
MCHK_D
FBTP
LK
99
-
00
2
5
A