Custom kernel .config options - best practice?

cas

What is the best way to maintain your own kernel .config options?

I recently added an RTC (DS3231) which involves adding RTC support and driver to the O2+ kernel.

Currently I hacked a couple of scripts which I can run after resetting the config files with git. These set the necessary options manually in both the kernel and package config files, but is there a better (proper?) way to do this?

Probably the different options should be set manually after running make menuconfig? But I don't know if the resulting .config file (after make menuconfig and saving .config) will build the same kernel as the one built with the .config from the Onion source repo. I'm doubtful that it will.

fwiw, here are the scripts I wrote in case anyone else finds them useful. I did some light testing, so use at own risk:

set-kerneloptions-RTCds1307.sh
#! /bin/sh

setoption() {
 local loption=$1
 local lstate=$2
 local lconfigfile=$3

 grep "${loption}\(=\| \)" ${lconfigfile} > /dev/null
 if [ $? -eq 0 ]; then
  # set it to the required value
  echo -n Set: ${loption}
  sed -i -r "s/^(${loption}=.*|# ${loption} is not set)/${loption}=${lstate}/" ${lconfigfile}
 else
  # Add the option
  echo -n Add: ${loption}
  echo "${loption}=${lstate}" >> ${lconfigfile}
 fi
 echo " Now: `grep "${loption}\(=\| \)" ${lconfigfile}`"
}

unsetoption() {
 local loption=$1
 local lconfigfile=$2

 grep "${loption}\(=\| \)" ${lconfigfile} > /dev/null
 if [ $? -eq 0 ]; then
  # set it to the required value
  echo -n Unset: ${loption}
  sed -i -r "s/^(${loption}=.*)/# ${loption} is not set/" ${lconfigfile}
 else
  # Add the option
  echo -n Add: ${loption}
  echo "# ${loption} is not set" >> ${lconfigfile}
 fi
 echo " Now: `grep "${loption}\(=\| \)" ${lconfigfile}`"
}

CONFIGFILE="target/linux/ramips/mt7688/config-4.4"

for configoption in CONFIG_RTC_CLASS \
                        CONFIG_RTC_DRV_DS1307 \
                        CONFIG_RTC_SUPPORT
do
 setoption "${configoption}" "y" "${CONFIGFILE}"
done

unsetoption "CONFIG_RTC_HCTOSYS" "${CONFIGFILE}"

Execution is as follows:

root@122126d368fa:~/source# git checkout target/linux/ramips/mt7688/config-4.4
root@122126d368fa:~/source# ./set-kerneloptions-RTCds1307.sh
Add: CONFIG_RTC_CLASS Now: CONFIG_RTC_CLASS=y
Add: CONFIG_RTC_DRV_DS1307 Now: CONFIG_RTC_DRV_DS1307=y
Add: CONFIG_RTC_SUPPORT Now: CONFIG_RTC_SUPPORT=y
Add: CONFIG_RTC_HCTOSYS Now: # CONFIG_RTC_HCTOSYS is not set
root@122126d368fa:~/source#

set-packages-RTCds1307.sh
#! /bin/sh

setoption() {
 local loption=$1
 local lstate=$2
 local lconfigfile=$3

 grep "${loption}\(=\| \)" ${lconfigfile} > /dev/null
 if [ $? -eq 0 ]; then
  # set it to the required value
  echo -n Set: ${loption}
  sed -i -r "s/^(${loption}=.*|# ${loption} is not set)/${loption}=${lstate}/" ${lconfigfile}
 else
  # Add the option
  echo -n Add: ${loption}
  echo "${loption}=${lstate}" >> ${lconfigfile}
 fi
 echo " Now: `grep "${loption}\(=\| \)" ${lconfigfile}`"
}

unsetoption() {
 local loption=$1
 local lconfigfile=$2

 grep "${loption}\(=\| \)" ${lconfigfile} > /dev/null
 if [ $? -eq 0 ]; then
  # set it to the required value
  echo -n Unset: ${loption}
  sed -i -r "s/^(${loption}=.*)/# ${loption} is not set/" ${lconfigfile}
 else
  # Add the option
  echo -n Add: ${loption}
  echo "# ${loption} is not set" >> ${lconfigfile}
 fi
 echo " Now: `grep "${loption}\(=\| \)" ${lconfigfile}`"
}

CONFIGFILE=".config"

for configoption in CONFIG_PACKAGE_kmod-i2c-core \
                        CONFIG_PACKAGE_kmod-i2c-algo-bit \
                        CONFIG_PACKAGE_kmod-i2c-gpio \
                        CONFIG_PACKAGE_kmod-i2c-gpio-custom \
                        CONFIG_PACKAGE_hwclock \
                        CONFIG_PACKAGE_i2c-tools \
                        CONFIG_PACKAGE_kmod-rtc-ds1307
do
 setoption "${configoption}" "y" "${CONFIGFILE}"
done

Execution is as follows:

root@122126d368fa:~/source# git checkout .config
root@122126d368fa:~/source# ./set-packages-RTCds1307.sh
Set: CONFIG_PACKAGE_kmod-i2c-core Now: CONFIG_PACKAGE_kmod-i2c-core=y
Set: CONFIG_PACKAGE_kmod-i2c-algo-bit Now: CONFIG_PACKAGE_kmod-i2c-algo-bit=y
Set: CONFIG_PACKAGE_kmod-i2c-gpio Now: CONFIG_PACKAGE_kmod-i2c-gpio=y
Set: CONFIG_PACKAGE_kmod-i2c-gpio-custom Now: CONFIG_PACKAGE_kmod-i2c-gpio-custom=y
Set: CONFIG_PACKAGE_hwclock Now: CONFIG_PACKAGE_hwclock=y
Set: CONFIG_PACKAGE_i2c-tools Now: CONFIG_PACKAGE_i2c-tools=y
Add: CONFIG_PACKAGE_kmod-rtc-ds1307 Now: CONFIG_PACKAGE_kmod-rtc-ds1307=y
root@122126d368fa:~/source#