We're running a 1062Q rack with an 8370+8371 and MXI-e x4 cable. No other cards are present in the rack (with the exception of the ones we are trying to test; see below).The host PCs (3 tested) are based on either Gigabyte or ASUS motherboards (all latest BIOS and drivers installed).We have developed two PCIe card; one a standard PCIe card (PC based, selectable as either 1-lane or 4-lane) and the other a PXIe card for the 1062Q rack (only 1-lane).The PCIe based card works flawlessly in the PC. The PXIe card also works in the PC (via an in-house adaptor). Either card in the PC or 1062Q works in as much as host PCIe enumeration is sucessful and their internal operational control registers and memory can be written and read.The problem arrises when the PXIe plug-in card attempts to perform MEMW TLPs (that is, DMA writes to the host memory) when it is in the 1062Q rack. The DMA writes never arrive at the host and eventually the host will lock-up.When either card is directly connected to the host, then the DMA works fine.We're currently at a loss in explaining this, and have started to look for a PXIe bus exerciser.Any pointers for what we can do next?

PXI

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And thanks to everyone that posted suggestions.

Still, I know this isn't the place to discuss the PCIe spec, but why is there a limitation on the addressing mode when the address is below 4GB?

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