RE: [RESEND PATCH] arm: Enlarge IO_SPACE_LIMIT needed for some SoC

David Laight
2021-05-09T16:55:09Z

...
> 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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