kconfig: add streamline_config.pl to scripts

streamline_config.pl is a very powerful tool. For those that install
a kernel to a new box using the config file from the distribution know that
it can take forever to compile the kernel.

Making a custom config file that will still boot your box, but bring
down the compile time of the kernel can be quit painful, and to ask
someone that reported a bug to do this can be a large burdon since that
person may not even know how to build a kernel.

This script will perform "lsmod" to find all the modules loaded on the
current running system. It will read all the Makefiles to map which
CONFIG enables a module. It will read the Kconfig files to find the
dependencies and selects that may be needed to support a CONFIG.
Finally, it reads the .config file and removes any module "=m" that is
not needed to enable the currently loaded modules. The output goes to
standard out.

Here's a way to run the script. From the Linux directory that holds
a distribution .config.

 $ scripts/kconfig/streamline_config.pl arch/x86/Kconfig > config-sl
 $ mv .config config-save
 $ mv config-sl .config
 $ make oldconfig

Now you have a .config that will still build all your modules, but also
take much less time to build the kernel.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

scripts/kconfig/streamline_config.pl

+#!/usr/bin/perl -w
+#
+# Copywrite 2005-2009 - Steven Rostedt
+# Licensed under the terms of the GNU GPL License version 2
+#
+#  It's simple enough to figure out how this works.
+#  If not, then you can ask me at stripconfig@goodmis.org
+#
+# 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, then 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 %depends;
+my %selects;
+my %prompts;
+my %objects;
+my $var;
+my $cont = 0;
+
+# Get the top level Kconfig file (passed in)
+my $kconfig = $ARGV[0];
+
+# prevent recursion
+my %read_kconfigs;
+
+sub read_kconfig {
+    my ($kconfig) = @_;
+
+    my $state = "NONE";
+    my $config;
+    my @kconfigs;
+
+    open(KIN, $kconfig) || die "Can't open $kconfig";
+    while (<KIN>) {
+	chomp;
+
+	# collect any Kconfig sources
+	if (/^source\s*"(.*)"/) {
+	    $kconfigs[$#kconfigs+1] = $1;
+	}
+
+	# configs found
+	if (/^\s*config\s+(\S+)\s*$/) {
+	    $state = "NEW";
+	    $config = $1;
+
+	# collect the depends for the config
+	} elsif ($state eq "NEW" && /^\s*depends\s+on\s+(.*)$/) {
+	    $state = "DEP";
+	    $depends{$config} = $1;
+	} elsif ($state eq "DEP" && /^\s*depends\s+on\s+(.*)$/) {
+	    $depends{$config} .= " " . $1;
+
+	# Get the configs that select this config
+	} elsif ($state ne "NONE" && /^\s*select\s+(\S+)/) {
+	    if (defined($selects{$1})) {
+		$selects{$1} .= " " . $config;
+	    } else {
+		$selects{$1} = $config;
+	    }
+
+	# configs without prompts must be selected
+	} elsif ($state ne "NONE" && /^\s*tristate\s\S/) {
+	    # note if the config has a prompt
+	    $prompt{$config} = 1;
+
+	# stop on "help"
+	} elsif (/^\s*help\s*$/) {
+	    $state = "NONE";
+	}
+    }
+    close(KIN);
+
+    # read in any configs that were found.
+    foreach $kconfig (@kconfigs) {
+	if (!defined($read_kconfigs{$kconfig})) {
+	    $read_kconfigs{$kconfig} = 1;
+	    read_kconfig($kconfig);
+	}
+    }
+}
+
+if ($kconfig) {
+    read_kconfig($kconfig);
+}
+
+# Read all Makefiles to map the configs to the objects
+foreach my $makefile (@makefiles) {
+    chomp $makefile;
+
+    open(MIN,$makefile) || die "Can't open $makefile";
+    while (<MIN>) {
+	my $objs;
+
+	# is this a line after a line with a backslash?
+	if ($cont && /(\S.*)$/) {
+	    $objs = $1;
+	}
+	$cont = 0;
+
+	# collect objects after obj-$(CONFIG_FOO_BAR)
+	if (/obj-\$\((CONFIG_[^\)]*)\)\s*[+:]?=\s*(.*)/) {
+	    $var = $1;
+	    $objs = $2;
+	}
+	if (defined($objs)) {
+	    # test if the line ends with a backslash
+	    if ($objs =~ m,(.*)\\$,) {
+		$objs = $1;
+		$cont = 1;
+	    }
+
+	    foreach my $obj (split /\s+/,$objs) {
+		$obj =~ s/-/_/g;
+		if ($obj =~ /(.*)\.o$/) {
+		    # Objects may bes enabled by more than one config.
+		    # Store configs in an array.
+		    my @arr;
+
+		    if (defined($objects{$1})) {
+			@arr = @{$objects{$1}};
+		    }
+
+		    $arr[$#arr+1] = $var;
+
+		    # The objects have a hash mapping to a reference
+		    # of an array of configs.
+		    $objects{$1} = \@arr;
+		}
+	    }
+	}
+    }
+    close(MIN);
+}
+
+my %modules;
+
+# see what modules are loaded on this system
+open(LIN,"/sbin/lsmod|") || die "Cant lsmod";
+while (<LIN>) {
+	next if (/^Module/);  # Skip the first line.
+	if (/^(\S+)/) {
+		$modules{$1} = 1;
+	}
+}
+close (LIN);
+
+# add to the configs hash all configs that are needed to enable
+# a loaded module.
+my %configs;
+foreach my $module (keys(%modules)) {
+    if (defined($objects{$module})) {
+	@arr = @{$objects{$module}};
+	foreach my $conf (@arr) {
+	    $configs{$conf} = $module;
+	}
+    } else {
+	# Most likely, someone has a custom (binary?) module loaded.
+	print STDERR "$module config not found!!\n";
+    }
+}
+
+my $valid = "A-Za-z_0-9";
+my $repeat = 1;
+
+#
+# Note, we do not care about operands (like: &&, ||, !) we want to add any
+# config that is in the depend list of another config. This script does
+# not enable configs that are not already enabled. If we come across a
+# config A that depends on !B, we can still add B to the list of depends
+# to keep on. If A was on in the original config, B would not have been
+# and B would not be turned on by this script.
+#
+sub parse_config_dep_select
+{
+    my ($p) = @_;
+
+    while ($p =~ /[$valid]/) {
+
+	if ($p =~ /^[^$valid]*([$valid]+)/) {
+	    my $conf = "CONFIG_" . $1;
+
+	    $p =~ s/^[^$valid]*[$valid]+//;
+
+	    if (!defined($configs{$conf})) {
+		# We must make sure that this config has its
+		# dependencies met.
+		$repeat = 1; # do again
+		$configs{$conf} = 1;
+	    }
+	} else {
+	    die "this should never happen";
+	}
+    }
+}
+
+while ($repeat) {
+    $repeat = 0;
+
+    foreach my $config (keys %configs) {
+	$config =~ s/^CONFIG_//;
+
+	if (!defined($depends{$config})) {
+	    next;
+	}
+
+	# This config has dependencies. Make sure they are also included
+	parse_config_dep_select $depends{$config};
+
+	if (defined($prompt{$config}) || !defined($selects{$config})) {
+	    next;
+	}
+
+	# config has no prompt and must be selected.
+	parse_config_dep_select $selects{$config};
+    }
+}
+
+my %setconfigs;
+
+# Finally, read the .config file and turn off any module enabled that
+# we could not find a reason to keep enabled.
+while(<CIN>) {
+	if (/^(CONFIG.*)=m/) {
+		if (defined($configs{$1})) {
+		    $setconfigs{$1} = 1;
+		    print;
+		} else {
+		    print "# $1 is not set\n";
+		}
+	} else {
+		print;
+	}
+}
+close(CIN);
+
+# Integrity check, make sure all modules that we want enabled do
+# indeed have their configs set.
+loop:
+foreach my $module (keys(%modules)) {
+    if (defined($objects{$module})) {
+	my @arr = @{$objects{$module}};
+	foreach my $conf (@arr) {
+	    if (defined($setconfigs{$conf})) {
+		next loop;
+	    }
+	}
+	print STDERR "module $module did not have configs";
+	foreach my $conf (@arr) {
+	    print STDERR " " , $conf;
+	}
+	print STDERR "\n";
+    }
+}