quiz-prepare-kernel

#!/usr/bin/env bash

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

# Copyright (c) 2023, Rob Norris <robn@despairlabs.com>

set -uo pipefail

usage() {
  cat <<EOF
compile a kernel optimised for the quiz microvm
usage: quiz-prepare-kernel [opts]

options:
  -k <kernel>     kernel to build
                    (can be used multiple times)
  -e/-d/-m <key>  set kernel config key to enable/disable/module (Y/N/M)
                    (can be used multiple times)
  -u              update standard config for this kernel minor version
  -L              build with LLVM/Clang
  -C              don't install kernel config before build
  -B              don't build kernel
  -K              build latest of all kernel series with available config
  -h              this help
EOF
  exit 1
}

trace() {
  local STAMP=$(date +%Y%m%d-%H:%M:%S)
  echo "[quiz-prepare-kernel] $STAMP $@" >&2
}

fail() {
  trace "FATAL $@"
  exit 1
}
trap fail ERR


RUNDIR=$(realpath $(dirname $0))
source $RUNDIR/quiz-config
source $RUNDIR/quiz-lib

opt_kernel=""
opt_no_config=""
opt_no_build=""
opt_llvm=""
opt_update_config=""
opt_modify_config=""
opt_all_kernels=""

OPTIND=1
while getopts "k:CBe:d:m:uLKh" opt
do
  case "$opt" in
    'k') opt_kernel="$opt_kernel $OPTARG" ;;
    'C') opt_no_config=1 ;;
    'B') opt_no_build=1 ;;
    'e') opt_modify_config="$opt_modify_config -e $OPTARG" ;;
    'd') opt_modify_config="$opt_modify_config -d $OPTARG" ;;
    'm') opt_modify_config="$opt_modify_config -m $OPTARG" ;;
    'u') opt_update_config=1 ;;
    'L') opt_llvm=1 ;;
    'K') opt_all_kernels=1 ;;
    'h') usage ;;
    *) exit 1 ;;
  esac
done
shift $(expr $OPTIND - 1)

cd $RUNDIR

if [[ -n $opt_kernel && -n $opt_all_kernels ]] ; then
  fail "invalid kernel version options; can't use -k and -K together"
fi
if [[ -z $opt_kernel && -z $opt_all_kernels ]] ; then
  fail "no kernel version supplied; one of -k or -K required"
fi

if [[ -n $opt_all_kernels ]] ; then
    opt_kernel=$(ls kernel/config-* | cut -d- -f2 | sort -V)
fi

makeopts=""
if [[ -n $opt_llvm ]] ; then
  IFS=:
  best_clang=$(find $PATH -maxdepth 1 -executable -name "clang-??" -print | \
    sed -Ee 's/^.+-//' | sort -r | head -1)
  unset IFS
  if [[ -z "$best_clang" ]] ; then
    trace "no specific clang found, setting LLVM=1"
    best_clang=1
  else
    trace "found clang-$best_clang, setting LLVM=-$best_clang"
    best_clang="-$best_clang"
  fi
  makeopts="$makeopts LLVM=$best_clang"
fi

declare -A kernel_sumfile

kernel_versions=""
for kver in $opt_kernel ; do
  _quiz_kernel_vars $kver
  if [[ $_quiz_kmajor && $_quiz_kminor && -z $_quiz_kpatch ]] ; then
    if [[ -z ${kernel_sumfile[$_quiz_kmajor]:-} ]] ; then
      sumfile=build/kernel/sha256sums.$_quiz_kmajor
      trace "fetching list of available kernels for v$_quiz_kmajor.x"
      if [[ ! -e $sumfile ]] ; then
        touch --date=@0 $sumfile
      fi
      curl -# -f -o $sumfile -z $sumfile -R \
        https://cdn.kernel.org/pub/linux/kernel/v$_quiz_kmajor.x/sha256sums.asc
      kernel_sumfile[$_quiz_kmajor]=$sumfile
    fi
    latest=$(cat ${kernel_sumfile[$_quiz_kmajor]} | \
      sed -Ene "/linux-.+\.tar.xz/ { s/.*linux-($kver\.[0-9]+)\.tar\.xz/\1/ p }" | tail -1)
    if [[ -z $latest ]] ; then
      trace "no available kernel for $kver"
      kver=""
    else
      trace "will build $latest for $kver"
      kver=$latest
    fi
  fi
  if [[ $kver ]] ; then
    kernel_versions="$kernel_versions $kver"
  fi
done

kernel_versions=$(echo $kernel_versions | xargs -n1 | sort -V | uniq | xargs)
trace "will build kernel versions: $kernel_versions"

for kver in $kernel_versions ; do
  quiz_kernel_vars $kver

  case $_quiz_ktype in
  release)
    ktar=linux-$_quiz_ksrcver.tar.xz
    kurl=https://cdn.kernel.org/pub/linux/kernel/v$_quiz_kmajor.x/$ktar
    kzopt=J
    ;;
  rc)
    ktar=linux-$_quiz_ksrcver.tar.gz
    kurl=https://git.kernel.org/torvalds/t/$ktar
    kzopt=z
    ;;
  *)
    fail "unknown kernel source type $_quiz_type"
  esac

  trace "preparing build: $_quiz_kver ($_quiz_ktype)"

  mkdir -p build
  if [[ -d build/kernel/linux-$_quiz_ksrcver ]] ; then
    trace "using existing source dir: build/kernel/linux-$_quiz_ksrcver"
  else
    trace "setting up for build in: build/kernel/linux-$_quiz_ksrcver"
    mkdir -p build/kernel
    pushd build/kernel > /dev/null
    if [[ -f $ktar ]] ; then
      trace "using existing tarball: $ktar"
    else
      trace "downloading: $kurl"
      curl -# -fOL $kurl
    fi
    tar xf$kzopt $ktar
    popd > /dev/null
  fi

  kcfg=config-$_quiz_kmajor.$_quiz_kminor
  if [[ -z $opt_no_config ]] ; then
    working_kcfg=$kcfg
    if [[ ! -f kernel/$working_kcfg ]] ; then
      trace "config not found: $working_kcfg"
      working_kcfg=$(ls kernel/config-$_quiz_kmajor.* | cut -f2 -d/ | tail -1)
    fi
    if [[ ! -f kernel/$working_kcfg ]] ; then
      trace "config not found: $working_kcfg"
      working_kcfg=$(ls kernel/config-* | cut -f2 -d/ | tail -1)
    fi
    if [[ ! -f kernel/$working_kcfg ]] ; then
      trace "config not found: $working_kcfg"
      fatal "no usable config found!"
    fi
    if [[ $kcfg != $working_kcfg ]] ; then
      trace "specific config not found, using fallback: $working_kcfg"
    fi

    trace "installing config: $working_kcfg"
    cp kernel/$working_kcfg build/kernel/linux-$_quiz_ksrcver/.config
  else
    trace "NOT installing config as requested"
  fi

  pushd build/kernel/linux-$_quiz_ksrcver > /dev/null

  if [[ -n $opt_modify_config ]] ; then
    trace "updating config from commandline switches"
    scripts/config $opt_modify_config
  fi

  trace "compiling config: $_quiz_ksrcver"

  make -s -j6 olddefconfig $makeopts

  if [[ -z $opt_no_build ]] ; then
    trace "building kernel: $_quiz_ksrcver"
    make -j6 $makeopts
  else
    trace "NOT building kernel as requested"
  fi

  popd > /dev/null

  if [[ -n $opt_update_config ]] ; then
    trace "updating standard config: $kcfg"
    cp build/kernel/linux-$_quiz_ksrcver/.config kernel/$kcfg
  fi

  if [[ -z $opt_no_build ]] ; then
    trace "moving completed kernel into quiz system dir: $_quiz_kver"

    mkdir -p system
    cp build/kernel/linux-$_quiz_ksrcver/arch/x86/boot/bzImage system/bzImage-$_quiz_kver
  fi

  trace "build finished: $_quiz_kver"
done

# vim: ft=bash