MicroBlaze Processor Reference Guide
67
UG081 (v14.7)
Reset, Interrupts, Exceptions, and Break
•
Unaligned Exception
•
Data Bus Exception
•
Divide Exception
•
FPU Exception
•
Stream Exception
Exception Causes
•
Stream Exception
The stream exception (FSL or AXI) is caused by executing a
get
or
getd
instruction with the
‘e’ bit set to ‘1’ when there is a control bit mismatch.
•
Instruction Bus Exception
The instruction bus exception is caused by errors when reading data from memory.
♦
The instruction peripheral AXI4 interface (M_AXI_IP) exception is caused by an error
response on
M_AXI_IP_RRESP
.
♦
The instruction cache AXI4 interface (M_AXI_IC) is caused by an error response on
M_AXI_IC_RRESP
. The exception can only occur when
C_ICACHE_ALWAYS_USED
is
set to 1 and the cache is turned off. In all other cases the response is ignored.
♦
The instruction Processor Local Bus (PLB) exception is caused by an active error signal
from the slave (
IPLB_MRdErr
) or timeout signal from the arbiter (
IPLB_MTimeout
).
♦
The instructions side local memory (ILMB) can only cause instruction bus exception
when
C_FAULT_TOLERANT
is set to 1, and either an uncorrectable error occurs in the
LMB memory, as indicated by the
IUE
signal, or
C_ECC_USE_CE_EXCEPTION
is set
to 1 and a correctable error occurs in the LMB memory, as indicated by the
ICE
signal.
♦
The CacheLink (IXCL) interfaces cannot cause instruction bus exceptions.
•
Illegal Opcode Exception
The illegal opcode exception is caused by an instruction with an invalid major opcode (bits 0
through 5 of instruction). Bits 6 through 31 of the instruction are not checked. Optional
processor instructions are detected as illegal if not enabled. If the optional feature
C_OPCODE_0x0_ILLEGAL
is enabled, an illegal opcode exception is also caused if the
instruction is equal to 0x00000000.
•
Data Bus Exception
The data bus exception is caused by errors when reading data from memory or writing data to
memory.
♦
The data peripheral AXI4 interface (M_AXI_DP) exception is caused by an error
response on
M_AXI_DP_RRESP
or
M_AXI_DP_BRESP
.
♦
The data cache AXI4 interface (M_AXI_DC) exception is caused by:
-
An error response on
M_AXI_DC_RRESP
or
M_AXI_DC_BRESP
,
-
OKAY
response on
M_AXI_DC_RRESP
in case of an exclusive access using
LWX
.
The exception can only occur when
C_DCACHE_ALWAYS_USED
is set to 1 and the cache
is turned off, or when an exclusive access using
LWX
or
SWX
is performed. In all other cases
the response is ignored.
♦
The data Processor Local Bus exception is caused by an active error signal from the slave
(
DPLB_MRdErr
or
DPLB_MWrErr
) or timeout signal from the arbiter
(
DPLB_MTimeout
).