On Monday 15 October 2007 11:29:58 pm Sam Ravnborg wrote:
> Hi Rob & Jan.
>
> On Fri, Oct 12, 2007 at 11:44:08PM +0200, Jan Engelhardt wrote:
> > Allow config variables in .config to override earlier ones in the same
> > file. In other words,
> >
> > # CONFIG_SECURITY is not defined
> > CONFIG_SECURITY=y
> >
> > will activate it. This makes it a bit easier to do
> >
> > (cat original-config myconfig myconfig2 ... >.config)
> >
> > and run menuconfig as expected.
>
> How far is this from the miniconfig functionality?
> Is it the same or can we achieve the miniconfig support
> by extending Jan's patch?
>
> See: http://lkml.org/lkml/2007/10/12/391
Way way back (2.6.10 or thereabouts) I first did a miniconfig via running
allnoconfig, concatenating a miniconfig to the result, and running "make
oldconfig" on that. This concatenation method had two main problems:
1) Around 2.6.15 the kconfig infrastructure changed so the first instance
symbol won rather than the last symbol. It looks like this patch just sets
the behavior back to what we had in 2.6.14 and earlier.
2) When a symbol activates new subsymbols (opening a new menu, for example),
those dependant symbols would be activated at their oldconfig default values,
not their allnoconfig default values. This meant there might be a valid
configuration that you couldn't specify without saying "symbol=n" to turn
some of them off in your miniconfig, which is something a miniconfig should
never have to do. (This happens when allnoconfig and oldconfig are run in
two separate passes. The oldconfig pass uses the wrong default values for
newly enabled symbols. Menuconfig has the same defaults as oldconfig, which
are _not_ the same defaults as allnoconfig.)
Note that the infrastructure I'm using to _read_ miniconfig files is just a
repurpose of the existing KCONFIG_ALLCONFIG as applied to allnoconfig.
That's in kconfig already, has been since 2.6.15-ish, and works fine. The
syntax is nonobvious (two patches from me to improve said syntax and add some
error checking were rejected), but the functionality is there and easy enough
to trigger:
make allnoconfig KCONFIG_ALLCONFIG=mini.conf
That expands a mini.conf into a .config, and does the other setup necessary.
(You can feed that O= to build out of tree, or ARCH= to build another
architecture... Anything you can currently do with allnoconfig.)
It's the "shrinking a .config into a mini.conf" side of things that uses a
hideous shell script that's not in the tree:
http://landley.net/hg/firmware/raw-file/tip/sources/toys/miniconfig.sh
To use it:
make ARCH=arm defconfig
mv .config tempname
ARCH=arm ./miniconfig.sh tempname
ls -l mini.config
(Obviously, the ARCH=arm is optional and you don't have to start with
defconfig.)
If I had unlimited spare time I might teach kconfig to automatically write a
mini.conf every time it writes a .config, and have it use whichever was newer
in the update commands (oldconfig/menuconfig/etc). But after two rejected
patches on this topic already, with the shell script meeting my needs, that's
impressively far down on my todo list.
Rob
--
"One of my most productive days was throwing away 1000 lines of code."
- Ken Thompson.
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