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PCI Deadlock Situations
94 Interphase Corporation
Example: The PCI host sets the DMA buffer descriptors into the local memory, and then
it runs the DMA (a write into a PowerSpan register). The DMA starts before the effective
completion of the buffer descriptors writes into the local 60x memory, so it loads a bad
addresses, a bad byte count, etc., and accomplishes the transfer with this bad data.
In this case, the PCI host must ensure that its latest write into the memory is effectively
finished locally, before starting the DMA.
PCI Deadlock Situations
Several deadlock situations can occur on the PCI bus. These situations will statistically
rarely occur, but they need to be treated by exception handlers, in order not to lock the
system.