Re: [RFC] Extending kbuild syntax

From: Sam Ravnborg
Date: Sun Sep 30 2007 - 06:28:00 EST

On Sun, Sep 30, 2007 at 05:02:58AM +0200, Adrian Bunk wrote:
> On Sat, Sep 29, 2007 at 10:11:45PM +0200, Sam Ravnborg wrote:
> >...
> > The second is the more controversial suggestion.
> > In several Makefile we have simple if expression of the variants:
> > if ($(CONFIG_FOO),y)
> > obj-$(CONFIG_BAR) += fubar.o
> > endif
> >
> > The pattern varies over this theme.
> > The suggestion here is to introduce a few helpers:
> >
> > obj-y-if-$(CONFIG_FOO) += fubar.o
> > This one shall read:
> > if $(CONFIG_FOO) is y or m then set += to obj-y
> IMHO for people who are not kbuild junkies the pattern is more clear
> with the current syntax.
> But you should better ask some guinea pigs who have not already seen as
> many kernel Makefiles as I have...

Target group are for kernel developers and people who have
actually read Documentation/kbuild/makefiles.txt

But point taken - this is too 'magic'.
I will try to think of something that looks a bit more straightforward.

> Some of the cases have the following pattern:
> config X86_POWERNOW_K8_ACPI
> bool
> depends on X86_POWERNOW_K8 && ACPI_PROCESSOR
> depends on !(X86_POWERNOW_K8 = y && ACPI_PROCESSOR = m)
> default y
> Your suggested syntax has to be enhanced with three additional
> variables for handling such cases.
> The complicated cases can be handled either in kconfig or in kbuild,
> and I think kconfig is the better place for them:

The kbuild enhancements are for the cases where it
makes less sense to express this in Kconfig.
They are not thought as replacing Kconfig dependencies in any way.

I will try to come up with a new proposal later today.

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