Config brainstorming

Brainstorming for enable Kconfig on compat-drivers

Step 1

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

cat .config | genkconf.sh > kernel-kconfig

where the script is this:

#!/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

Step 2

Collect all Kconfig symbols from compat:

find . -name Kconfig | xargs cat | sed 's/^config //;t;d' > symbols

Step 3

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

find . -name Makefile | xargs rpl "CONFIG_" "CONFIG_COMPAT_"

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

Step 4

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

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

Step 5

Build a Kconfig file:

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

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

Step 6

Run menuconfig:

/lib/modules/$(uname -r)/build/scripts/kconfig/mconf Kconfig

Step 7

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.