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

Geert Uytterhoeven
2007-06-28T18:27:32Z

On Thu, 28 Jun 2007, Andrew Morton wrote:
> On Thu, 28 Jun 2007 15:37:15 +0200 Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
>
> > From: Heiko Carstens <heiko.carstens@de.ibm.com>
> >
> > check_signature() uses readb() and therefore should only be build on
> > CONFIG_HAS_IOMEM.
> >
> > Otherwise breaks s390:
> > lib/check_signature.c: In function `check_signature':
> > lib/check_signature.c:19: error: implicit declaration of function `readb'
> >
>
> Ah, right, I've been discussing identical m68k breakage with Roman and Geert.
>
> > ---
> > lib/Makefile | 5 ++---
> > 1 files changed, 2 insertions(+), 3 deletions(-)
> >
> > Index: linux-2.6.22-rc6-mm1/lib/Makefile
> > ===================================================================
> > --- linux-2.6.22-rc6-mm1.orig/lib/Makefile
> > +++ linux-2.6.22-rc6-mm1/lib/Makefile
> > @@ -5,8 +5,7 @@
> > lib-y := ctype.o string.o vsprintf.o cmdline.o \
> > rbtree.o radix-tree.o dump_stack.o \
> > idr.o int_sqrt.o bitmap.o extable.o prio_tree.o \
> > - sha1.o irq_regs.o reciprocal_div.o argv_split.o \
> > - check_signature.o
> > + sha1.o irq_regs.o reciprocal_div.o argv_split.o
> >
> > lib-$(CONFIG_MMU) += ioremap.o pagewalk.o
> > lib-$(CONFIG_SMP) += cpumask.o
> > @@ -22,7 +21,7 @@ CFLAGS_kobject_uevent.o += -DDEBUG
> > 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.

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