On Fri, Dec 17, 2021 at 2:19 PM Niklas Schnelle <schnelle@xxxxxxxxxxxxx> wrote: > > I've had some time to look into this a bit. As a refreshed starting > point I have rebased Arnd's patch to v5.16-rc5. Since I'm not sure how > to handle authorship and it's very early I haven't sent it as RFC but > it's available as a patch from my GitHub here: > https://gist.github.com/niklas88/a08fe76bdf9f5798500fccea6583e275 > > I have incorporated the following findings from this thread already: > > - Added HAS_IOPORT to arch Kconfigs > - Added "config LEGACY_PCI" to drivers/pci/Kconfig > - Fixed CONFIG_HAS_IOPORT typo in asm-generic/io.h > - Removed LEGACY_PCI dependency of i2c-i801. > Which is also used in current gen Intel platforms > and depends on x86 anyway. > > I have tested this on s390 with HAS_IOPORT=n and allyesconfig as well > as running it with defconfig. I've also been using it on my Ryzen 3990X > workstation with LEGACY_PCI=n for a few days. I do get about 60 MiB > fewer modules compared with a similar config of v5.15.8. Hard to say > which other systems might miss things of course. > > I have not yet worked on the discussed IOPORT_NATIVE flag. Mostly I'm > wondering two things. For one it feels like that could be a separate > change on top since HAS_IOPORT + LEGACY_PCI is already quite big. > Secondly I'm wondering about good ways of identifying such drivers and > how much this overlaps with the ISA config flag. > > I'd of course appreciate feedback. If you agree this is still > worthwhile to persue I'd think the next step would be trying to > refactor this into more manageable patches. Thanks a lot for restarting this work! I think this all looks reasonable (a lot was my original patch anyway, so of course I think that ;)), but it would be good to split it up into multiple patches. The CONFIG_LEGACY_PCI should take care of a lot of it, and I think that can be a single patch. I'd expand the Kconfig description to explain that this also covers PCIe devices that use the legacy I/O space even if they do not have a PCIe-to-PCI bridge in them. The introduction of CONFIG_HAS_IOPORT, plus selecting it from the respective architectures makes sense as another patch, but I would make that separate from the #ifdef and 'depends on' changes to individual subsystems or drivers, as they are better reviewed separately. Arnd
