9-4
MPC106 PCIB/MC User's Manual
MOTOROLA
The MPC106 holds MCP asserted until the 60x processor has taken the exception. The
MPC106 decodes an interrupt acknowledge cycle by detecting 60x processor reads from
the two possible machine check exception addresses at 0x0000_0200–0x0000_0207 and
0xFFF0_0200–0xFFF0_0207.
The MCP signal can be configured, by programming PMCR2[SHARED_MCP], as an
output-only or as an open drain output signal. When configured for output-only, the
MPC106 always drives the MCP signal. When configured for open drain output, the
MPC106 drives the MCP signal only when signalling a detected error. Otherwise, the
MPC106 releases MCP to a high-impedance state. The open drain configuration allows
other devices to signal MCP to the 60x processor without contention.
9.2.2.2 Transfer Error Acknowledge (TEA)
The MPC106 asserts TEA to signal to the 60x processor that a nonrecoverable error has
occurred during data transfer on the 60x processor data bus. The assertion of TEA depends
upon whether the error handling registers of the MPC106 are set to report the specific error.
Assertion of TEA terminates the data transaction in progress; that is, it is not necessary to
assert TA because it will be ignored by the target processor. An unsupported transaction
causes the assertion of TEA (provided TEA is enabled). Unsupported transactions include:
A direct-store access
A graphics read or write (
eciwx
or
ecowx
)
A write to the PCI interrupt-acknowledge space (map A or map B)
A write to system ROM space, when Flash writes are disabled
An aborted processor-to-PCI transaction
The assertion of TEA causes the 60x processor to conditionally take a machine check
exception or enter the checkstop state based on the setting of the MSR[ME] bit in the 60x
processor.
The TEA signal may be asserted on any cycle that DBB is asserted. The assertion of TEA
terminates the data tenure immediately, even if in the middle of a burst. The MPC106
asserts TEA for only one clock. Note that the assertion of TEA does not prevent corrupt
data from being written into the cache or GPRs of the 60x processor.
The programmable parameter PICR1[TEA_EN] is used to enable or disable the assertion
of TEA by the MPC106. If PICR1[TEA_EN] is programmed to disable the assertion of
TEA, and a 60x processor data transfer error occurs, then the MPC106 asserts TA the
appropriate number of times to complete the transaction, but the data is unpredictable.