generate-config.pl's auto modules feature answers "m" to any Kconfig question it thinks supports being a module. It detected this by seeing if the help shown by make config (called "alts" by the script) contained the string "/m", which it would in the case of e.g a tristate option, where alts would be "N/m/y/?". But then along came CONFIG_MODPROBE_PATH in Linux 5.13, with a default value, shown in the make config help, of "/sbin/modprobe". generate-config.pl would see the "/m" substring, and answer "m" to the question, meaning (I think) that the built kernel would expect the modprobe binary to be at /m. This broke the (non-NixOS) VM images I build with Nix. NixOS was unaffected because it uses a different mechanism to set the modprobe path. With the current architecture, we can't 100% determine whether a Kconfig option is a string or a tristate, but we can get a lot closer by using a better regex. My new regex only accepts single word characters, separated by slashes, with a "/?" at the end. This is much less likely to ever end up as the default value of a string option. Tested by building linux_latest.configfile before and after my changes, and checking the only difference is the correct default for CONFIG_MODPROBE_PATH.
155 lines
5.4 KiB
Perl
155 lines
5.4 KiB
Perl
# This script runs `make config' to generate a Linux kernel
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# configuration file. For each question (i.e. kernel configuration
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# option), unless an override is provided, it answers "m" if possible,
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# and otherwise uses the default answer (as determined by the default
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# config for the architecture). Overrides are read from the file
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# $KERNEL_CONFIG, which on each line contains an option name and an
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# answer, e.g. "EXT2_FS_POSIX_ACL y". The script warns about ignored
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# options in $KERNEL_CONFIG, and barfs if `make config' selects
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# another answer for an option than the one provided in
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# $KERNEL_CONFIG.
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use strict;
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use IPC::Open2;
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use Cwd;
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# exported via nix
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my $debug = $ENV{'DEBUG'};
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my $autoModules = $ENV{'AUTO_MODULES'};
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my $preferBuiltin = $ENV{'PREFER_BUILTIN'};
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my $ignoreConfigErrors = $ENV{'ignoreConfigErrors'};
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my $buildRoot = $ENV{'BUILD_ROOT'};
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my $makeFlags = $ENV{'MAKE_FLAGS'};
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$SIG{PIPE} = 'IGNORE';
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# Read the answers.
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my %answers;
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my %requiredAnswers;
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open ANSWERS, "<$ENV{KERNEL_CONFIG}" or die "Could not open answer file";
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while (<ANSWERS>) {
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chomp;
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s/#.*//;
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if (/^\s*([A-Za-z0-9_]+)(\?)?\s+(.*\S)\s*$/) {
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$answers{$1} = $3;
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$requiredAnswers{$1} = !(defined $2);
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} elsif (!/^\s*$/) {
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die "invalid config line: $_";
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}
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}
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close ANSWERS;
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sub runConfig {
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# Run `make config'.
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my $pid = open2(\*IN, \*OUT, "make -C $ENV{SRC} O=$buildRoot config SHELL=bash ARCH=$ENV{ARCH} CC=$ENV{CC} HOSTCC=$ENV{HOSTCC} HOSTCXX=$ENV{HOSTCXX} $makeFlags");
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# Parse the output, look for questions and then send an
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# appropriate answer.
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my $line = ""; my $s;
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my %choices = ();
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my ($prevQuestion, $prevName);
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while (!eof IN) {
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read IN, $s, 1 or next;
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$line .= $s;
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#print STDERR "LINE: $line\n";
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if ($s eq "\n") {
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print STDERR "GOT: $line" if $debug;
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# Remember choice alternatives ("> 1. bla (FOO)" or " 2. bla (BAR) (NEW)").
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if ($line =~ /^\s*>?\s*(\d+)\.\s+.*?\(([A-Za-z0-9_]+)\)(?:\s+\(NEW\))?\s*$/) {
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$choices{$2} = $1;
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} else {
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# The list of choices has ended without us being
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# asked. This happens for options where only one value
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# is valid, for instance. The results can foul up
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# later options, so forget about it.
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%choices = ();
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}
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$line = "";
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}
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elsif ($line =~ /###$/) {
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# The config program is waiting for an answer.
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# Is this a regular question? ("bla bla (OPTION_NAME) [Y/n/m/...] ")
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if ($line =~ /(.*) \(([A-Za-z0-9_]+)\) \[(.*)\].*###$/) {
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my $question = $1; my $name = $2; my $alts = $3;
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my $answer = "";
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# Build everything as a module if possible.
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$answer = "m" if $autoModules && $alts =~ qr{\A(\w/)+m/(\w/)*\?\z} && !($preferBuiltin && $alts =~ /Y/);
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$answer = $answers{$name} if defined $answers{$name};
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print STDERR "QUESTION: $question, NAME: $name, ALTS: $alts, ANSWER: $answer\n" if $debug;
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print OUT "$answer\n";
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die "repeated question: $question" if $prevQuestion && $prevQuestion eq $question && $name eq $prevName;
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$prevQuestion = $question;
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$prevName = $name;
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}
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# Is this a choice? ("choice[1-N]: ")
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elsif ($line =~ /choice\[(.*)\]: ###$/) {
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my $answer = "";
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foreach my $name (keys %choices) {
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$answer = $choices{$name} if ($answers{$name} || "") eq "y";
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}
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print STDERR "CHOICE: $1, ANSWER: $answer\n" if $debug;
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print OUT "$answer\n" if $1 =~ /-/;
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}
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# Some questions lack the option name ("bla bla [Y/n/m/...] ").
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elsif ($line =~ /(.*) \[(.*)\] ###$/) {
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print OUT "\n";
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}
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else {
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warn "don't know how to answer this question: $line\n";
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print OUT "\n";
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}
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$line = "";
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%choices = ();
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}
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}
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close IN;
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waitpid $pid, 0;
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}
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# Run `make config' several times to converge on the desired result.
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# (Some options may only become available after other options are
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# set in a previous run.)
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runConfig;
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runConfig;
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# Read the final .config file and check that our answers are in
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# there. `make config' often overrides answers if later questions
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# cause options to be selected.
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my %config;
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open CONFIG, "<$buildRoot/.config" or die "Could not read .config";
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while (<CONFIG>) {
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chomp;
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if (/^CONFIG_([A-Za-z0-9_]+)="(.*)"$/) {
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# String options have double quotes, e.g. 'CONFIG_NLS_DEFAULT="utf8"' and allow escaping.
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($config{$1} = $2) =~ s/\\([\\"])/$1/g;
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} elsif (/^CONFIG_([A-Za-z0-9_]+)=(.*)$/) {
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$config{$1} = $2;
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} elsif (/^# CONFIG_([A-Za-z0-9_]+) is not set$/) {
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$config{$1} = "n";
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}
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}
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close CONFIG;
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my $ret = 0;
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foreach my $name (sort (keys %answers)) {
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my $f = $requiredAnswers{$name} && $ignoreConfigErrors ne "1"
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? sub { warn "error: " . $_[0]; $ret = -1; } : sub { warn "warning: " . $_[0]; };
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&$f("unused option: $name\n") unless defined $config{$name};
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&$f("option not set correctly: $name (wanted '$answers{$name}', got '$config{$name}')\n")
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if $config{$name} && $config{$name} ne $answers{$name};
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}
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exit $ret;
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