2 machine status save/restore register 1 (srr1) – IBM POWERPC 750GL User Manual

Page 157

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User’s Manual

IBM PowerPC 750GX and GL RISC Microprocessor

gx_04.fm.(1.2)
March 27, 2006

Exceptions

Page 157 of 377

4.3.2 Machine Status Save/Restore Register 1 (SRR1)

SRR1 is used to save machine status (selected MSR bits and possibly other status bits as well) on excep-
tions and to restore those values when a Return from Interrupt (rfi) instruction is executed.

When the 750GX takes a machine-check exception, it will set one or more error bits in SRR1, in Hardware-
Implementation-Dependent Register 2 (HID2), or in the L2 Cache Control Register (L2CR). A parity error in
either the internal L2 tag array or instruction-cache or data-cache tag arrays is indicated by the CP bit. A data-
parity error on the 60x bus is indicated by the DP bit. The MCpin bit indicates that the machine-check pin was
activated. The transfer error acknowledge (TEA) bit indicates the machine check was caused by a TEA
response on the 60x bus. An address-parity error on the 60x bus will set the AP bit.

Reserved

CP

Reserved

L2DBE

RR

MCpin

TE

A

DP AP

Reserved

0

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Bits

Field Name

Description

0:3

Reserved

4

CP

Set when an internal cache parity error is detected.

5:10

Reserved

11

L2DBERR

Set when an L2 data-cache ECC double-bit error is detected.

12

MCpin

Set when the machine-check pin is asserted.

13

TEA

Set when a transfer error acknowledge (TEA) error is detected.

14

DP

Set when a data-bus parity error is detected.

15

AP

Set when an address-bus parity error is detected.

16:31

Reserved

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