From: John Garry <email@example.com>
To: Arnd Bergmann <firstname.lastname@example.org>
Cc: Linus Torvalds <email@example.com>,
"Linux Kernel Mailing List" <firstname.lastname@example.org>,
Niklas Schnelle <email@example.com>
Subject: Re: [GIT PULL 1/2] asm-generic: rework PCI I/O space access
Date: Tue, 3 Aug 2021 12:23:55 +0100 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
>> 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,
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
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
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
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.
next prev parent reply other threads:[~2021-08-03 11:24 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-02 13:47 [GIT PULL 1/2] asm-generic: rework PCI I/O space access Arnd Bergmann
2021-07-02 13:49 ` [GIT PULL 2/2] asm-generic: Unify asm/unaligned.h around struct helper Arnd Bergmann
2021-07-02 20:13 ` pr-tracker-bot
2021-07-02 19:42 ` [GIT PULL 1/2] asm-generic: rework PCI I/O space access Linus Torvalds
2021-07-03 12:12 ` Arnd Bergmann
2021-07-05 10:06 ` Arnd Bergmann
2021-08-03 9:46 ` John Garry
2021-08-03 10:06 ` Arnd Bergmann
2021-08-03 11:23 ` John Garry [this message]
2021-08-03 12:15 ` Arnd Bergmann
2021-08-04 7:55 ` John Garry
2021-08-04 8:52 ` Arnd Bergmann
2021-08-10 9:19 ` John Garry
2021-08-10 11:33 ` Arnd Bergmann
2021-09-03 8:31 ` Niklas Schnelle
2021-12-17 13:19 ` Niklas Schnelle
2021-12-17 13:32 ` Arnd Bergmann
2021-12-17 13:52 ` Niklas Schnelle
2021-12-17 14:05 ` Arnd Bergmann
2021-12-17 14:27 ` John Garry
2021-12-17 14:32 ` Arnd Bergmann
2021-12-17 15:27 ` John Garry
2021-12-17 15:55 ` Arnd Bergmann
2021-12-17 16:30 ` John Garry
2021-12-20 9:27 ` Niklas Schnelle
2021-12-21 16:48 ` John Garry
2021-12-21 16:57 ` Niklas Schnelle
2021-12-19 14:23 ` David Laight
2021-12-21 16:21 ` John Garry
2021-07-05 12:40 ` Niklas Schnelle
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