nixpkgs/pkgs/os-specific/linux/kernel/generate-config.pl
Shea Levy f95d214cfd Implement generic kernel build via manual-config
This has three major benefits:

1. We no longer have two kernel build processes to maintain

2. The build process is (IMO) cleaner and cleaves more closely to
upstream. In partuclar, we use make install to install the kernel and
development source/build trees, eliminating the guesswork about which
files to copy.

3. The derivation has multiple outputs: the kernel and modules are in
the default `out' output, while the build and source trees are in a
`dev' output. This makes it possible for the full source and build tree
to be kept (which is expected by out-of-tree modules) without bloating
the closure of the system derivation.

In addition, if a solution for how to handle queries in the presence of
imports from derivations ever makes it into nix, a framework for
querying the full configuration of the kernel in nix expressions is
already in place.

Signed-off-by: Shea Levy <shea@shealevy.com>
2014-01-01 09:21:25 -05:00

142 lines
4.5 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;
my $wd = getcwd;
my $debug = $ENV{'DEBUG'};
my $autoModules = $ENV{'AUTO_MODULES'};
$SIG{PIPE} = 'IGNORE';
# Read the answers.
my %answers;
my %requiredAnswers;
open ANSWERS, "<$ENV{KERNEL_CONFIG}" or die;
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 $ENV{SRC} O=$wd config SHELL=bash ARCH=$ENV{ARCH}");
# 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;
}
$line = "";
}
elsif ($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 =~ /\/m/;
$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 $pid, 0;
}
# Run `make config' several times to converge on the desired result.
# (Some options may only become available after other options are
# set in a previous run.)
runConfig;
runConfig;
# Read the final .config file and check that our answers are in
# there. `make config' often overrides answers if later questions
# cause options to be selected.
my %config;
open CONFIG, "<.config" or die;
while (<CONFIG>) {
chomp;
if (/^CONFIG_([A-Za-z0-9_]+)=(.*)$/) {
$config{$1} = $2;
} elsif (/^# CONFIG_([A-Za-z0-9_]+) is not set$/) {
$config{$1} = "n";
}
}
close CONFIG;
foreach my $name (sort (keys %answers)) {
my $f = $requiredAnswers{$name} && $ENV{'ignoreConfigErrors'} ne "1"
? sub { die @_; } : sub { warn @_; };
&$f("unused option: $name\n") unless defined $config{$name};
&$f("option not set correctly: $name\n")
if $config{$name} && $config{$name} ne $answers{$name};
}