nixpkgs/pkgs/os-specific/linux/kernel/generate-config.pl
Alyssa Ross fb079c3110 linux.configfile: fix alts containing "/m"
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.
2022-03-10 11:13:11 +00:00

155 lines
5.4 KiB
Perl

# This script runs `make config' to generate a Linux kernel
# configuration file. For each question (i.e. kernel configuration
# option), unless an override is provided, it answers "m" if possible,
# and otherwise uses the default answer (as determined by the default
# config for the architecture). Overrides are read from the file
# $KERNEL_CONFIG, which on each line contains an option name and an
# answer, e.g. "EXT2_FS_POSIX_ACL y". The script warns about ignored
# options in $KERNEL_CONFIG, and barfs if `make config' selects
# another answer for an option than the one provided in
# $KERNEL_CONFIG.
use strict;
use IPC::Open2;
use Cwd;
# exported via nix
my $debug = $ENV{'DEBUG'};
my $autoModules = $ENV{'AUTO_MODULES'};
my $preferBuiltin = $ENV{'PREFER_BUILTIN'};
my $ignoreConfigErrors = $ENV{'ignoreConfigErrors'};
my $buildRoot = $ENV{'BUILD_ROOT'};
my $makeFlags = $ENV{'MAKE_FLAGS'};
$SIG{PIPE} = 'IGNORE';
# Read the answers.
my %answers;
my %requiredAnswers;
open ANSWERS, "<$ENV{KERNEL_CONFIG}" or die "Could not open answer file";
while (<ANSWERS>) {
chomp;
s/#.*//;
if (/^\s*([A-Za-z0-9_]+)(\?)?\s+(.*\S)\s*$/) {
$answers{$1} = $3;
$requiredAnswers{$1} = !(defined $2);
} elsif (!/^\s*$/) {
die "invalid config line: $_";
}
}
close ANSWERS;
sub runConfig {
# Run `make config'.
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");
# Parse the output, look for questions and then send an
# appropriate answer.
my $line = ""; my $s;
my %choices = ();
my ($prevQuestion, $prevName);
while (!eof IN) {
read IN, $s, 1 or next;
$line .= $s;
#print STDERR "LINE: $line\n";
if ($s eq "\n") {
print STDERR "GOT: $line" if $debug;
# Remember choice alternatives ("> 1. bla (FOO)" or " 2. bla (BAR) (NEW)").
if ($line =~ /^\s*>?\s*(\d+)\.\s+.*?\(([A-Za-z0-9_]+)\)(?:\s+\(NEW\))?\s*$/) {
$choices{$2} = $1;
} else {
# The list of choices has ended without us being
# asked. This happens for options where only one value
# is valid, for instance. The results can foul up
# later options, so forget about it.
%choices = ();
}
$line = "";
}
elsif ($line =~ /###$/) {
# The config program is waiting for an answer.
# Is this a regular question? ("bla bla (OPTION_NAME) [Y/n/m/...] ")
if ($line =~ /(.*) \(([A-Za-z0-9_]+)\) \[(.*)\].*###$/) {
my $question = $1; my $name = $2; my $alts = $3;
my $answer = "";
# Build everything as a module if possible.
$answer = "m" if $autoModules && $alts =~ qr{\A(\w/)+m/(\w/)*\?\z} && !($preferBuiltin && $alts =~ /Y/);
$answer = $answers{$name} if defined $answers{$name};
print STDERR "QUESTION: $question, NAME: $name, ALTS: $alts, ANSWER: $answer\n" if $debug;
print OUT "$answer\n";
die "repeated question: $question" if $prevQuestion && $prevQuestion eq $question && $name eq $prevName;
$prevQuestion = $question;
$prevName = $name;
}
# Is this a choice? ("choice[1-N]: ")
elsif ($line =~ /choice\[(.*)\]: ###$/) {
my $answer = "";
foreach my $name (keys %choices) {
$answer = $choices{$name} if ($answers{$name} || "") eq "y";
}
print STDERR "CHOICE: $1, ANSWER: $answer\n" if $debug;
print OUT "$answer\n" if $1 =~ /-/;
}
# Some questions lack the option name ("bla bla [Y/n/m/...] ").
elsif ($line =~ /(.*) \[(.*)\] ###$/) {
print OUT "\n";
}
else {
warn "don't know how to answer this question: $line\n";
print OUT "\n";
}
$line = "";
%choices = ();
}
}
close IN;
waitpid $pid, 0;
}
# Run `make config' several times to converge on the desired result.
# (Some options may only become available after other options are
# set in a previous run.)
runConfig;
runConfig;
# Read the final .config file and check that our answers are in
# there. `make config' often overrides answers if later questions
# cause options to be selected.
my %config;
open CONFIG, "<$buildRoot/.config" or die "Could not read .config";
while (<CONFIG>) {
chomp;
if (/^CONFIG_([A-Za-z0-9_]+)="(.*)"$/) {
# String options have double quotes, e.g. 'CONFIG_NLS_DEFAULT="utf8"' and allow escaping.
($config{$1} = $2) =~ s/\\([\\"])/$1/g;
} elsif (/^CONFIG_([A-Za-z0-9_]+)=(.*)$/) {
$config{$1} = $2;
} elsif (/^# CONFIG_([A-Za-z0-9_]+) is not set$/) {
$config{$1} = "n";
}
}
close CONFIG;
my $ret = 0;
foreach my $name (sort (keys %answers)) {
my $f = $requiredAnswers{$name} && $ignoreConfigErrors ne "1"
? sub { warn "error: " . $_[0]; $ret = -1; } : sub { warn "warning: " . $_[0]; };
&$f("unused option: $name\n") unless defined $config{$name};
&$f("option not set correctly: $name (wanted '$answers{$name}', got '$config{$name}')\n")
if $config{$name} && $config{$name} ne $answers{$name};
}
exit $ret;