Messages in this thread | | | Subject | Re: [GIT PULL 1/2] asm-generic: rework PCI I/O space access | From | John Garry <> | Date | Tue, 3 Aug 2021 12:23:55 +0100 |
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>> 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.
Great
> >> 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,
ok, it would be nice to see that.
> 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.
That seems reasonable. And asm-generic io.h should be ifdef'ed by HAS_IOPORT. In your patch you had it under CONFIG_IOPORT - was that intentional?
On another point, I noticed SCSI driver AHA152x depends on ISA, but is not an isa driver - however it does use port IO. Would such dependencies need to be changed to depend on HAS_IOPORT?
I did notice that arm32 support CONFIG_ISA - not sure why.
> > 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.
Yeah, that sounds the same as what I was thinking. Maybe IOPORT_NATIVE could work as a name. I would think that only x86/ia64 would define it. A concern though is that someone could argue that is a functional dependency, rather than just a build dependency.
Thanks, John
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