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MPC8240 Integrated Processor User’s Manual
Exceptions and Error Signals
The internal machine check signal indicates to the processor that a nonrecoverable error has
occurred during system operation. The state of mcp is provided externally on the MCP
output signal. The assertion of mcp depends upon whether the error handling registers of
the MPC8240 are set to report the specific error. The programmable parameter
PICR1[MCP_EN] is used to enable or disable the assertion of mcp by the MPC8240 for all
error conditions. Assertion of mcp causes the processor core to take a machine check
exception conditionally or enter the checkstop state based on the value of the processor’s
MSR[ME] bit.
The machine check signal may be asserted to the processor core on any cycle. Whether the
current transaction is aborted depends upon the software configuration.
The MPC8240 holds mcp asserted until the processor core has taken the exception. The
MPC8240 decodes a machine check acknowledge cycle by detecting processor reads from
the two possible machine check exception addresses at 0x0000_0200–0x0000_0207 and
0xFFF0_0200–0xFFF0_0207, and negates mcp. Note that if the MPC8240 is configured for
remote ROM (that is, ROM space is located in the PCI memory space), then a processor
read from 0xFFF0_0200 will not negate the mcp signal. In this case, the machine check
exception handler must perform a dummy read from 0x0000_0200 to cause the negation of
mcp.
13.2.3 PCI Bus Error Signals
The MPC8240 uses three error signals to interact with the PCI bus—SERR, PERR, and
NMI.
13.2.3.1 System Error (SERR)
The SERR signal is used to report PCI system errors—PCI address parity error, PCI data
parity error on a special-cycle command, target-abort, or any other error where the result is
potentially catastrophic. The SERR signal is also asserted for master-abort, except for PCI
configuration accesses or special-cycle transactions.
The agent responsible for driving AD[31–0] on a given PCI bus phase is responsible for
driving even parity one PCI clock cycle later on the PAR signal. That is, the number of 1s
on AD[31–0], C/BE[3–0], and PAR equals an even number.
The SERR signal is driven for a single PCI clock cycle by the agent that is reporting the
error. The target agent is not allowed to terminate with retry or disconnect if SERR is
activated due to an address parity error.
Bit 8 of the PCI command register controls whether the MPC8240 asserts SERR upon
detecting any PCI system error. Whenever the MPC8240 asserts SERR to report a system
error on the PCI bus, bit 14 of the PCI status register is set.
Bit 7 of ErrEnR1 enables the reporting (via mcp, if enabled) of SERR assertion by an
external agent on the PCI bus. If ErrEnR1[7] = 1 with MPC8240 acting as the initiator, and
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...