500
March 2002 Release
1-800-255-7778
Virtex-II Pro™ Platform FPGA Documentation
Chapter 7:
Exceptions and Interrupts
R
See the specific instruction for details.
SRR3 is loaded with a copy of the MSR when a critical interrupt occurs. An
rfci
instruction
restores the machine state by copying the contents of SRR3 into the MSR (defined and
reserved MSR fields are updated).
SRR2 is a privileged SPR with an address of 990 (0x3DE) and SRR3 is a privileged SPR with
an address of 991 (0x3DF). Both registers are read and written using the
mfspr
and
mtspr
instructions.
Exception-Vector Prefix Register
The exception-vector prefix register (EVPR) is a 32-bit register that contains the base
address of the interrupt-handler table. Software can locate the interrupt-handler table
anywhere in physical-address space, with a base address that falls on a 64KB-aligned
boundary. When an exception occurs, the high-order 16 bits in EVPR are concatenated on
the left with the 16-bit exception-vector offset (the low-order 16 reserved bits in the EVPR
are ignored by the processor). The resulting 32-bit exception-vector physical address is
used by the interrupt mechanism to transfer control to the appropriate interrupt handler.
shows the format of the EVPR register. The fields in the EVPR are defined as
shown in
The EVPR is a privileged SPR with an address of 982 (0x3D6) and is read and written using
the
mfspr
and
mtspr
instructions.
Exception-Syndrome Register
The exception-syndrome register (ESR) is a 32-bit register used to identify the cause of the
following exceptions:
•
Program exception.
•
Instruction machine-check exception.
•
Instruction-storage exception.
•
Data-storage exception.
•
Data TLB-miss exception.
shows the format of the ESR register. The fields in the ESR are defined as shown
0
15 16
31
EVP
Figure 7-4:
Exception-Vector Prefix Register (EVPR)
Table 7-4:
Exception-Vector Prefix Register (EVPR) Field Definitions
Bit
Name
Function
Description
0:15
EVP
Exception-Vector Prefix
Used to locate the interrupt-handler table base address on an
arbitrary 64KB physical-address boundary.
16:31
Reserved
0
1
3
4
5
6
7
8
9
10 11
12
13
14 15
16
17
31
MCI
PIL PPR PTR PEU DST DIZ
PFP PAP
U0F
Figure 7-5:
Exception-Syndrome Register (ESR)
Содержание Virtex-II Pro PPC405
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