Re: [patch -mm] Make check_signature() depend on CONFIG_HAS_IOMEM

Geert Uytterhoeven
2007-06-28T18:47:42Z

On Thu, 28 Jun 2007, Andrew Morton wrote:
> On Thu, 28 Jun 2007 20:27:22 +0200 (CEST) Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > > endif
> > > >
> > > > obj-$(CONFIG_GENERIC_IOMAP) += iomap.o
> > > > -obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o
> > > > +obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o check_signature.o
> > > > obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o
> > > > obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
> > > > lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
> > >
> > > We didn't think of that.
> > >
> > > Alas, m68k `make allmodconfig' creates CONFIG_ISA=n, CONFIG_PCI=n,
> > > CONFIG_HAS_IOMEM=y, so it will still be busted.
> > >
> > > But this seems to be the correct fix. Perhaps m68k config needs
> > > attention?
> >
> > Euh, I don't think this is the correct fix.
> >
> > CONFIG_HAS_IOMEM is apparently used in two meanings:
> > 1. The architecture has support for memory mapped I/O (s390 obviously
> > hasn't)
> > 2. The architecture has ISA/PCI-style memory mapped I/O (readb() and
> > friends)
> >
> > check_signature() falls under the second category.
> >
> > Setting NO_IOMEM on m68k will make us loose some drivers (e.g.
> > drivers/video/Kconfig depends on HAS_IOMEM).
> >
> > Apart from many Kconfig dependencies on HAS_IOMEM, CONFIG_HAS_IOMEM is
> > further only used to control the build of lib/iomap_copy.c, which
> > doesn't use readb() and friends, but the __raw*() operations.
> >
>
> Well this is fun.
>
> How to fix? Should we add a new CONFIG_HAS_IO? (IOPORTS?)

There already exists a CONFIG_HAS_IOPORT :-) (for ISA/PCI-style I/O port
access).

Just make check_signature() depend on ISA || PCI (and maybe || X86_32).
According to its comment, it's used to `find BIOS signatures', which is
a legacy PC thing. Please don't pollute non-legacy architectures with it ;-)

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds