Messages in this thread | | | Date | Tue, 20 Mar 2007 22:06:51 +0100 (CET) | From | Geert Uytterhoeven <> | Subject | kconfig `bool' (was: Re: [PATCH 13/13] fix ps3fb glue allowing a modular build) |
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On Wed, 14 Mar 2007, Linus Torvalds wrote: > On Wed, 14 Mar 2007, Al Viro wrote: > > Nope. How can kconfig distinguish that from a boolean option in modular > > driver? bool *can* depend on tristate and be selected when tristate is > > set to m. > > Btw, this is one of those things that easily causes problems. > > In many ways it would be nice if we had two different kinds of "bool": one > where "m" in the dependency chain means "y" is ok, and one where "m" means > "n". > > We used to have "dep_bool" and "dep_mbool" for this, a long time ago. It > got dropped in the Kconfig language rewrite, and I think it was a mistake. > > So I think it would be nice to re-introduce it. As it is, we have a number > of Kconfig language constructs that are just unnecessarily hard to > understand, because we end up having to add a "= y" or similar. > > The rule *used* to be: "dep_mbool" was a boolean that was valid even for > modules, while "dep_bool" was a boolean that was valid only for straigth > "y", and a module would turn it off. > > Maybe not "bool" vs "mbool", but it might be nice to have > > bool FB_PS3 > depends strictly on FB > > ie a "depends strictly" refuses to upgrade a bool dependency from "m" to > "y", while a regular depends allows it. > > Or something.. The "depends strictly on X" thing would really be just a > mental shorthand for "depends on (X)=y" (it's actually longer to type, but > I think it's a bit more intuitive, thus "mental shortcut").
I've been thinking about this a bit more...
Kconfig knows about the following types: o bool o tristate o string o hex o int
However, from a semantical point of view, they can be subdivided in 2 classes: 1. driver/subsystem/library enablers (i.e. things that are used in a Makefile to decide whether to compile a unit or not): o tristate (y=builtin, m=loadable, n=disabled) o bool (y=builtin, n=disabled) 2. options (i.e. things that control some features, limits, or default values): o bool (y=true, n=false) o string (literal) o hex (literal) o int (literal)
The confusion arises from the 2 different semantics for `bool': for the former, a `depends on' obviously cannot be `builtin' if the dependency is `modular', while for the latter, it can be `true' if the dependency is `modular'.
It would be nice if Kconfig would make the distinction between the two types of `bool' explicit. Anyone with a good replacement name for the first type of `bool'? I can't find one.
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- Sony Network and Software Technology Center Europe (NSCE) Geert.Uytterhoeven@sonycom.com ------- The Corporate Village, Da Vincilaan 7-D1 Voice +32-2-7008453 Fax +32-2-7008622 ---------------- B-1935 Zaventem, Belgium - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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