On Tue, Aug 3, 2021 at 11:46 AM John Garry <john.garry@xxxxxxxxxx> wrote: > On 05/07/2021 11:06, Arnd Bergmann wrote: > > > > Linus, if you like this approach, then I can work on splitting it up into > > meaningful patches and submit it for a future release. I think the > > CONFIG_LEGACY_PCI option has value on its own, but the others > > do introduce some churn. > > > > Full patch (120KB): https://pastebin.com/yaFSmAuY > > > > Hi Arnd, > > I am not sure if anything is happening here. No, I'm not currently working on this, though I have it applied to my randconfig tree. > Anyway, one thing I mentioned earlier was that we could solve the > problem of drivers accessing unmapped IO ports and crashing systems on > archs which define PCI_IOBASE by building them under some "native port > IO support" flag. Right, that was part of the goal here. > One example of such a driver was F71805F sensor. You put that under > HAS_IOPORT, which would be available for all archs, I think. But I could > not see where config LEGACY_PCI is introduced. Could we further refine > that config to not build for such archs as arm64? > > BTW, I think that the PPC dependency was added there to stop building > for power for that same reason, so hopefully we get rid of that. Good point. It seems that I actually never added the LEGACY_PCI option to my patch, so I'm just not building those drivers any more, and not defining the inb()/outb() helpers either, causing a build failure when I'm missing an option. However it sounds like you are interested in a third option here, which brings us to: LEGACY_PCI: any PCI driver that uses inb()/outb() or is only available on old-style PCI but not PCIe hardware without a bridge. To be disabled for most architectures and possibly distros but can be enabled for kernels that want to use those devices, as long as CONFIG_HAS_IOPORT is set by the architecture. HAS_IOPORT: not a legacy PCI device, but can only be built on architectures that define inb()/outb(). To be disabled for s390 and any other machine that has no useful definition of those functions. HARDCODED_IOPORT: (or another name you might think of,) Used by drivers that unconditionally do inb()/outb() without checking the validity of the address using firmware or other methods first. depends on HAS_IOPORT and possibly architecture specific settings. Arnd
