9 May
2021
9 May
'21
4:54 p.m.
...
Well, an obvious question would be: do you really need that much IO space? PCs have got away with 64K of IO space without having a problem for years, so 64K per bus should be fine. If you have 3 buses, that should be 3 * 64K or 192K.
Not only that, but most modern PCI (even) cards don't require IO space. Or does this include memory space - which can be much bigger.
I have cut one of our FPGA PCIe slaves down from two 8MB BARs to two 1MB ones, with the extra small BARs (eg for MSI-X) the bridge would have allocated 32MB, now 4MB. Fortunately that card only needs to work on x86-64.
David
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