View source for Config-brainstorming

Brainstorming for enable Kconfig on compat-drivers

<h1>Step 1</h1>

Using the existing kernel's config, generate a Kconfig file that contains all the right symbols for that kernel:

<code>
<pre>
cat .config | genkconf.sh > kernel-kconfig
</pre>
</code>

where the script is this:

<code>
<pre>
#!/bin/bash

while read line ; do
	case "${line:0:7}" in
	"CONFIG_")
		line="${line:7}"
		cfg="${line%%=*}"
		val="${line#*=}"
		cfgtype="skip"
		if [ "$val" = "m" ] ; then
			cfgtype="tristate"
		elif [ "$val" = "y" ] ; then
			cfgtype="bool"
		fi
		if [ "$cfgtype" != "skip" ] ; then
			echo "config $cfg"
			echo "    $cfgtype"
			echo "    default $val"
			echo ""
		fi
		;;
	"# CONFI")
		cfg="${line:9}"
		cfg="${cfg%% is not set}"
		echo "config $cfg"
		echo "    bool"
		echo "    default n"
		echo ""
		;;
	esac
done
</pre>
</code>

<h1>Step 2</h1>

Collect all Kconfig symbols from compat:
<code>
<pre>
find . -name Kconfig | xargs cat | sed 's/^config //;t;d' > symbols
</pre>
</code>

<h1>Step 3</h1>

Instead of patching Makefiles, replaces all CONFIG_ by CONFIG_COMPAT_ in all Makefiles:

<code><pre>
find . -name Makefile | xargs rpl "CONFIG_" "CONFIG_COMPAT_"
</pre></code>

This means that only things that are actually selected in compat will be built.

<h1>Step 4</h1>

Replace all "FOO" with "COMPAT_FOO" symbols in Kconfig and code files:

<code><pre>
for sym in $(cat symbols) ; do
    find . -name Kconfig |\
        xargs rpl -w "$sym" "COMPAT_$sym"

    find . -name '*.c' -o -name '*.h' |\
        xargs rpl -w "CONFIG_$sym" "CONFIG_COMPAT_$sym"
done
</pre></code>

<h1>Step 5</h1>

Build a Kconfig file:

<code><pre>
echo 'source "kernel-kconfig"' > Kconfig
for k in drivers/net/wireless/*/Kconfig ; do echo "source \"$k\"" >> Kconfig ; done
</pre></code>

etc. Currently, mac80211/cfg80211/... Kconfig isn't copied. They will need to be copied and potentially modified for dependencies like WEXT.

<h1>Step 6</h1>
Run menuconfig:

<code><pre>
/lib/modules/$(uname -r)/build/scripts/kconfig/mconf Kconfig
</pre></code>

<h1>Step 7</h1>

Build the thing.

The generated .config can be parsed with either the existing compat-drivers/scripts/gen-compat-autoconf.sh script or scripts/kconfig/confdata.c (conf --silentoldconfig). The generated include/linux/compat_autoconf.h is already included as part of the build of compat-drivers.