1#!/usr/bin/perl -w
2#
3# Copyright 2005-2009 - Steven Rostedt
4# Licensed under the terms of the GNU GPL License version 2
5#
6#  It's simple enough to figure out how this works.
7#  If not, then you can ask me at stripconfig@goodmis.org
8#
9# What it does?
10#
11#   If you have installed a Linux kernel from a distribution
12#   that turns on way too many modules than you need, and
13#   you only want the modules you use, then this program
14#   is perfect for you.
15#
16#   It gives you the ability to turn off all the modules that are
17#   not loaded on your system.
18#
19# Howto:
20#
21#  1. Boot up the kernel that you want to stream line the config on.
22#  2. Change directory to the directory holding the source of the
23#       kernel that you just booted.
24#  3. Copy the configuraton file to this directory as .config
25#  4. Have all your devices that you need modules for connected and
26#      operational (make sure that their corresponding modules are loaded)
27#  5. Run this script redirecting the output to some other file
28#       like config_strip.
29#  6. Back up your old config (if you want too).
30#  7. copy the config_strip file to .config
31#  8. Run "make oldconfig"
32#
33#  Now your kernel is ready to be built with only the modules that
34#  are loaded.
35#
36# Here's what I did with my Debian distribution.
37#
38#    cd /usr/src/linux-2.6.10
39#    cp /boot/config-2.6.10-1-686-smp .config
40#    ~/bin/streamline_config > config_strip
41#    mv .config config_sav
42#    mv config_strip .config
43#    make oldconfig
44#
45use strict;
46
47my $config = ".config";
48
49my $uname = `uname -r`;
50chomp $uname;
51
52my @searchconfigs = (
53	{
54	    "file" => ".config",
55	    "exec" => "cat",
56	},
57	{
58	    "file" => "/proc/config.gz",
59	    "exec" => "zcat",
60	},
61	{
62	    "file" => "/boot/config-$uname",
63	    "exec" => "cat",
64	},
65	{
66	    "file" => "/boot/vmlinuz-$uname",
67	    "exec" => "scripts/extract-ikconfig",
68	    "test" => "scripts/extract-ikconfig",
69	},
70	{
71	    "file" => "vmlinux",
72	    "exec" => "scripts/extract-ikconfig",
73	    "test" => "scripts/extract-ikconfig",
74	},
75	{
76	    "file" => "/lib/modules/$uname/kernel/kernel/configs.ko",
77	    "exec" => "scripts/extract-ikconfig",
78	    "test" => "scripts/extract-ikconfig",
79	},
80	{
81	    "file" => "kernel/configs.ko",
82	    "exec" => "scripts/extract-ikconfig",
83	    "test" => "scripts/extract-ikconfig",
84	},
85	{
86	    "file" => "kernel/configs.o",
87	    "exec" => "scripts/extract-ikconfig",
88	    "test" => "scripts/extract-ikconfig",
89	},
90);
91
92sub find_config {
93    foreach my $conf (@searchconfigs) {
94	my $file = $conf->{"file"};
95
96	next if ( ! -f "$file");
97
98	if (defined($conf->{"test"})) {
99	    `$conf->{"test"} $conf->{"file"} 2>/dev/null`;
100	    next if ($?);
101	}
102
103	my $exec = $conf->{"exec"};
104
105	print STDERR "using config: '$file'\n";
106
107	open(CIN, "$exec $file |") || die "Failed to run $exec $file";
108	return;
109    }
110    die "No config file found";
111}
112
113find_config;
114
115# Get the build source and top level Kconfig file (passed in)
116my $ksource = $ARGV[0];
117my $kconfig = $ARGV[1];
118my $lsmod_file = $ARGV[2];
119
120my @makefiles = `find $ksource -name Makefile 2>/dev/null`;
121chomp @makefiles;
122
123my %depends;
124my %selects;
125my %prompts;
126my %objects;
127my $var;
128my $iflevel = 0;
129my @ifdeps;
130
131# prevent recursion
132my %read_kconfigs;
133
134sub read_kconfig {
135    my ($kconfig) = @_;
136
137    my $state = "NONE";
138    my $config;
139    my @kconfigs;
140
141    my $cont = 0;
142    my $line;
143
144    my $source = "$ksource/$kconfig";
145    my $last_source = "";
146
147    # Check for any environment variables used
148    while ($source =~ /\$(\w+)/ && $last_source ne $source) {
149	my $env = $1;
150	$last_source = $source;
151	$source =~ s/\$$env/$ENV{$env}/;
152    }
153
154    open(KIN, "$source") || die "Can't open $kconfig";
155    while (<KIN>) {
156	chomp;
157
158	# Make sure that lines ending with \ continue
159	if ($cont) {
160	    $_ = $line . " " . $_;
161	}
162
163	if (s/\\$//) {
164	    $cont = 1;
165	    $line = $_;
166	    next;
167	}
168
169	$cont = 0;
170
171	# collect any Kconfig sources
172	if (/^source\s*"(.*)"/) {
173	    $kconfigs[$#kconfigs+1] = $1;
174	}
175
176	# configs found
177	if (/^\s*(menu)?config\s+(\S+)\s*$/) {
178	    $state = "NEW";
179	    $config = $2;
180
181	    for (my $i = 0; $i < $iflevel; $i++) {
182		if ($i) {
183		    $depends{$config} .= " " . $ifdeps[$i];
184		} else {
185		    $depends{$config} = $ifdeps[$i];
186		}
187		$state = "DEP";
188	    }
189
190	# collect the depends for the config
191	} elsif ($state eq "NEW" && /^\s*depends\s+on\s+(.*)$/) {
192	    $state = "DEP";
193	    $depends{$config} = $1;
194	} elsif ($state eq "DEP" && /^\s*depends\s+on\s+(.*)$/) {
195	    $depends{$config} .= " " . $1;
196
197	# Get the configs that select this config
198	} elsif ($state ne "NONE" && /^\s*select\s+(\S+)/) {
199	    if (defined($selects{$1})) {
200		$selects{$1} .= " " . $config;
201	    } else {
202		$selects{$1} = $config;
203	    }
204
205	# configs without prompts must be selected
206	} elsif ($state ne "NONE" && /^\s*tristate\s\S/) {
207	    # note if the config has a prompt
208	    $prompts{$config} = 1;
209
210	# Check for if statements
211	} elsif (/^if\s+(.*\S)\s*$/) {
212	    my $deps = $1;
213	    # remove beginning and ending non text
214	    $deps =~ s/^[^a-zA-Z0-9_]*//;
215	    $deps =~ s/[^a-zA-Z0-9_]*$//;
216
217	    my @deps = split /[^a-zA-Z0-9_]+/, $deps;
218
219	    $ifdeps[$iflevel++] = join ':', @deps;
220
221	} elsif (/^endif/) {
222
223	    $iflevel-- if ($iflevel);
224
225	# stop on "help"
226	} elsif (/^\s*help\s*$/) {
227	    $state = "NONE";
228	}
229    }
230    close(KIN);
231
232    # read in any configs that were found.
233    foreach $kconfig (@kconfigs) {
234	if (!defined($read_kconfigs{$kconfig})) {
235	    $read_kconfigs{$kconfig} = 1;
236	    read_kconfig($kconfig);
237	}
238    }
239}
240
241if ($kconfig) {
242    read_kconfig($kconfig);
243}
244
245# Read all Makefiles to map the configs to the objects
246foreach my $makefile (@makefiles) {
247
248    my $cont = 0;
249
250    open(MIN,$makefile) || die "Can't open $makefile";
251    while (<MIN>) {
252	my $objs;
253
254	# is this a line after a line with a backslash?
255	if ($cont && /(\S.*)$/) {
256	    $objs = $1;
257	}
258	$cont = 0;
259
260	# collect objects after obj-$(CONFIG_FOO_BAR)
261	if (/obj-\$\((CONFIG_[^\)]*)\)\s*[+:]?=\s*(.*)/) {
262	    $var = $1;
263	    $objs = $2;
264	}
265	if (defined($objs)) {
266	    # test if the line ends with a backslash
267	    if ($objs =~ m,(.*)\\$,) {
268		$objs = $1;
269		$cont = 1;
270	    }
271
272	    foreach my $obj (split /\s+/,$objs) {
273		$obj =~ s/-/_/g;
274		if ($obj =~ /(.*)\.o$/) {
275		    # Objects may be enabled by more than one config.
276		    # Store configs in an array.
277		    my @arr;
278
279		    if (defined($objects{$1})) {
280			@arr = @{$objects{$1}};
281		    }
282
283		    $arr[$#arr+1] = $var;
284
285		    # The objects have a hash mapping to a reference
286		    # of an array of configs.
287		    $objects{$1} = \@arr;
288		}
289	    }
290	}
291    }
292    close(MIN);
293}
294
295my %modules;
296
297if (defined($lsmod_file)) {
298    if ( ! -f $lsmod_file) {
299	die "$lsmod_file not found";
300    }
301    if ( -x $lsmod_file) {
302	# the file is executable, run it
303	open(LIN, "$lsmod_file|");
304    } else {
305	# Just read the contents
306	open(LIN, "$lsmod_file");
307    }
308} else {
309
310    # see what modules are loaded on this system
311    my $lsmod;
312
313    foreach my $dir ( ("/sbin", "/bin", "/usr/sbin", "/usr/bin") ) {
314	if ( -x "$dir/lsmod" ) {
315	    $lsmod = "$dir/lsmod";
316	    last;
317	}
318}
319    if (!defined($lsmod)) {
320	# try just the path
321	$lsmod = "lsmod";
322    }
323
324    open(LIN,"$lsmod|") || die "Can not call lsmod with $lsmod";
325}
326
327while (<LIN>) {
328	next if (/^Module/);  # Skip the first line.
329	if (/^(\S+)/) {
330		$modules{$1} = 1;
331	}
332}
333close (LIN);
334
335# add to the configs hash all configs that are needed to enable
336# a loaded module.
337my %configs;
338foreach my $module (keys(%modules)) {
339    if (defined($objects{$module})) {
340	my @arr = @{$objects{$module}};
341	foreach my $conf (@arr) {
342	    $configs{$conf} = $module;
343	}
344    } else {
345	# Most likely, someone has a custom (binary?) module loaded.
346	print STDERR "$module config not found!!\n";
347    }
348}
349
350my $valid = "A-Za-z_0-9";
351my $repeat = 1;
352
353#
354# Note, we do not care about operands (like: &&, ||, !) we want to add any
355# config that is in the depend list of another config. This script does
356# not enable configs that are not already enabled. If we come across a
357# config A that depends on !B, we can still add B to the list of depends
358# to keep on. If A was on in the original config, B would not have been
359# and B would not be turned on by this script.
360#
361sub parse_config_dep_select
362{
363    my ($p) = @_;
364
365    while ($p =~ /[$valid]/) {
366
367	if ($p =~ /^[^$valid]*([$valid]+)/) {
368	    my $conf = "CONFIG_" . $1;
369
370	    $p =~ s/^[^$valid]*[$valid]+//;
371
372	    if (!defined($configs{$conf})) {
373		# We must make sure that this config has its
374		# dependencies met.
375		$repeat = 1; # do again
376		$configs{$conf} = 1;
377	    }
378	} else {
379	    die "this should never happen";
380	}
381    }
382}
383
384while ($repeat) {
385    $repeat = 0;
386
387    foreach my $config (keys %configs) {
388	$config =~ s/^CONFIG_//;
389
390	if (defined($depends{$config})) {
391	    # This config has dependencies. Make sure they are also included
392	    parse_config_dep_select $depends{$config};
393	}
394
395	if (defined($prompts{$config}) || !defined($selects{$config})) {
396	    next;
397	}
398
399	# config has no prompt and must be selected.
400	parse_config_dep_select $selects{$config};
401    }
402}
403
404my %setconfigs;
405
406# Finally, read the .config file and turn off any module enabled that
407# we could not find a reason to keep enabled.
408while(<CIN>) {
409
410    if (/CONFIG_IKCONFIG/) {
411	if (/# CONFIG_IKCONFIG is not set/) {
412	    # enable IKCONFIG at least as a module
413	    print "CONFIG_IKCONFIG=m\n";
414	    # don't ask about PROC
415	    print "# CONFIG_IKCONFIG_PROC is not set\n";
416	} else {
417	    print;
418	}
419	next;
420    }
421
422    if (/^(CONFIG.*)=(m|y)/) {
423	if (defined($configs{$1})) {
424	    $setconfigs{$1} = $2;
425	} elsif ($2 eq "m") {
426	    print "# $1 is not set\n";
427	    next;
428	}
429    }
430    print;
431}
432close(CIN);
433
434# Integrity check, make sure all modules that we want enabled do
435# indeed have their configs set.
436loop:
437foreach my $module (keys(%modules)) {
438    if (defined($objects{$module})) {
439	my @arr = @{$objects{$module}};
440	foreach my $conf (@arr) {
441	    if (defined($setconfigs{$conf})) {
442		next loop;
443	    }
444	}
445	print STDERR "module $module did not have configs";
446	foreach my $conf (@arr) {
447	    print STDERR " " , $conf;
448	}
449	print STDERR "\n";
450    }
451}
452