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Subject[Announce] Stream line modules from .config with

Hi all,

I'm not sure if someone else did this, but I wrote this simple script that
turns off the modules from your config file that you are not currently
using. After downloading a new kernel I usually use the .config from my
Debian distribution. But this usually has way too many modules turned on
and my compile takes much longer than I prefer. So instead of searching
for all the modules that I need in "make *config" I wrote this script to
do it for me.

It's a small simple perl script (that's why it's attached and not on some
web site), and it can easily have options added to it, but it's good
enough for me, so that's where I left it.

Here's how it works and what it does.

1. Boot up the kernel that has the modules you want to load.
2. cd to the directory that holds the source of the kernel you
just booted.
3. If it's not already there, copy the config file you want to start
with to this directory, as .config.
4. Make sure all the modules you want/need are loaded.
5. run this script redirecting the output to another file.
6. copy this other file to .config (backing up your old one if you want).
7. Run "make oldconfig".

What this script does is simply, reads all the makefiles in the current
directory tree (find . -name Makefile). Searches each of these Makefiles
for the string "obj-$(CONFIG.*) += ..." (the real regular expression is
more complex, and the file is attached if you want to see it). It then
stores the object files associated to the CONFIG_.* and it handles
multiple lines that end with "\".

Then it runs "lsmod" to get what modules are loaded.

Finally it reads the .config file in the directory and prints it to
standard output. When it finds a CONFIG_.*=m it checks to see if that
config had an object from lsmod associated to it, if so, then it prints it
as is, otherwise it turns it off.

Here's what I did with my Debian distribution:

cd /usr/src/linux-2.6.10
cp /boot/config-2.6.10-1-686-smp .config
~/bin/streamline_config > config_strip
mv .config config_sav
mv config_strip .config
make oldconfig
Now this is the config file that I start with when downloading other

Obviously if you don't load all the modules you want, or later buy a
new device that needs a module that wasn't loaded, you will need to figure
out what module to add and compile it. Or use the saved config again
(you did save it?) and do this all over.

Well, do what you want with this, it's an unrescricted license. Comments?

If someone else had already done something like this, let me know. But I
wrote this and a colleage of mine suggested to send it here. So here it


-- Steve

#!/usr/bin/perl -w
# Copywrite 2005 - Steven Rostedt
# This code has no restrictions and NO WARRANTY.
# Use it at your own risk, do what you want with it,
# Just don't blame me.
# It's simple enough to figure out how this works.
# If not, then you can ask me at
# What it does?
# If you have installed a Linux kernel from a distribution
# that turns on way too many modules than you need, and
# you only want the modules you use, than this program
# is perfect for you.
# It gives you the ability to turn off all the modules that are
# not loaded on your system.
# Howto:
# 1. Boot up the kernel that you want to stream line the config on.
# 2. Change directory to the directory holding the source of the
# kernel that you just booted.
# 3. Copy the configuraton file to this directory as .config
# 4. Have all your devices that you need modules for connected and
# operational (make sure that their corresponding modules are loaded)
# 5. Run this script redirecting the output to some other file
# like config_strip.
# 6. Back up your old config (if you want too).
# 7. copy the config_strip file to .config
# 8. Run "make oldconfig"
# Now your kernel is ready to be built with only the modules that
# are loaded.
# Here's what I did with my Debian distribution.
# cd /usr/src/linux-2.6.10
# cp /boot/config-2.6.10-1-686-smp .config
# ~/bin/streamline_config > config_strip
# mv .config config_sav
# mv config_strip .config
# make oldconfig
my $config = ".config";
my $linuxpath = ".";
open(CIN,$config) || die "Can't open current config file: $config";
my @makefiles = `find $linuxpath -name Makefile`;
my %objects;
my $var;
my $cont = 0;
foreach my $makefile (@makefiles) {
chomp $makefile;
open(MIN,$makefile) || die "Can't open $makefile";
while (<MIN>) {
my $catch = 0;
if ($cont && /(\S.*)$/) {
$objs = $1;
$catch = 1;
$cont = 0;
if (/obj-\$\((CONFIG_[^)]*)\)\s*[+:]?=\s*(.*)/) {
$var = $1;
$objs = $2;
$catch = 1;
if ($catch) {
if ($objs =~ m,(.*)/$,) {
$objs = $1;
$cont = 1;
foreach my $obj (split /\s+/,$objs) {
$obj =~ s/-/_/g;
if ($obj =~ /(.*)\.o$/) {
$objects{$1} = $var;
my %modules;
open(LIN,"/sbin/lsmod|") || die "Cant lsmod";
while (<LIN>) {
next if (/^Module/); # Skip the first line.
if (/^(\S+)/) {
$modules{$1} = 1;
close (LIN);
my %configs;
foreach my $module (keys(%modules)) {
if (defined($objects{$module})) {
$configs{$objects{$module}} = $module;
} else {
print STDERR "$module config not found!!\n";
while(<CIN>) {
if (/^(CONFIG.*)=m/) {
if (defined($configs{$1})) {
} else {
print "# $1 is not set\n";
} else {
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