Comment 4 for bug 1862121

------- Comment From <email address hidden> 2020-02-19 02:53 EDT-------
Some additional comments about the impact of the patches. They only impact powerpc and more specifically the powernv platform. Opencapi devices are only supported on the powernv platform, and require a Power9 processor.

The first 5 patches (powerpc/powernv/pci-ioda) impact the opencapi PCI devices, and to a much lesser extent the nvlink (GPU) devices.
Patch 05dd7da76986 ("powerpc/powernv/ioda: Fix ref count for devices with their own PE") technically impacts nvlink (GPUs) PCI devices, but I'm only replacing a refcounting leak by a (oh so slightly) less ugly leak.
Patch 80f1ff83fa11("powerpc/powernv/ioda: Protect PE list") is for both nvlink and opencapi, but it looks pretty safe. nvlink devices are discovered at boot and never go away. Opencapi devices, with that series, can now come and go, that's why I'm adding the extra lock protection.
The 3 other patches for powerpc/powernv/pci-ioda really impact opencapi PCI devices only.

The second part of the series is for the powernv PCI hotplug driver (pnv-php) but there's little there other than adding the new opencapi slots. For existing PCI slots, it's mostly cosmetics.

Finally, the last patch is to add a dependency on the PCI hotplug framework for the ocxl driver. Ocxl is the opencapi driver. As mentioned above, it is only used of Power9 and it's the driver I'm maintaining.

I hope it clarifies things. I do believe the impact is fairly limited outside of opencapi device support and I'm trying pretty hard to make that work.