x86image pluginΒΆ

x86 image build element

A ScriptElement implementation for creating x86 disk images

The x86image default configuration:
#x86 image default configuration

variables:
  # Size of the disk to create
  #
  # Should be able to calculate this based on the space
  # used, however it must be a multiple of (63 * 512) bytes
  # as mtools wants a size that is devisable by sectors (512 bytes)
  # per track (63).
  boot-size: 252000K
  rootfs-size: 4G
  swap-size: 1G
  sector-size: 512

  kernel-args: root=/dev/sda2 rootfstype=ext4 rootdelay=20 init=/sbin/init

config:
  # The element that should be staged into "/". It must contain
  # all the tools required to generate the image
  # base: image-tools.bst

  # The element that should be staged into %{build-root}. It is expected
  # to be the system that you're planning to turn into an image.
  # input: foo-system.bst

  filesystem-tree-setup-commands:
  - |
    # XXX Split up the boot directory and the other
    #
    # This should be changed so that the /boot directory
    # is created separately.
  
    cd /buildstream
    mkdir -p /buildstream/boot
    mv %{build-root}/boot/* /buildstream/boot
  
  - |
    # Generate an fstab
    cat > %{build-root}/etc/fstab << EOF
    /dev/sda2   /       ext4   defaults,rw,noatime   0 1
    /dev/sda1   /boot   vfat   defaults              0 2
    /dev/sda3   none    swap   defaults              0 0
    EOF
  
  - |
    # Create the syslinux config
    mkdir -p /buildstream/boot/syslinux
    cat > /buildstream/boot/syslinux/syslinux.cfg << EOF
    PROMPT 0
    TIMEOUT 5
  
    ALLOWOPTIONS 1
    SERIAL 0 115200
  
    DEFAULT boot
    LABEL boot
  
    KERNEL /vmlinuz
    INITRD /initramfs.gz
  
    APPEND %{kernel-args}
    EOF
  filesystem-image-creation-commands:
  - |
    # Create the vfat image
    truncate -s %{boot-size} /buildstream/sda1.img
    mkdosfs /buildstream/sda1.img

  - |
    # Copy all that stuff into the image
    mcopy -D s -i /buildstream/sda1.img -s /buildstream/boot/* ::/

  - |
    # Install the bootloader on the image, it should get the config file
    # from inside the vfat image, I think
    syslinux --directory /syslinux/ /buildstream/sda1.img

  - |
    # Now create the root filesys on sda2
    truncate -s %{rootfs-size} /buildstream/sda2.img
    mkfs.ext4 -F -i 8192 -L root -d %{build-root} /buildstream/sda2.img

  - |
    # Create swap
    truncate -s %{swap-size} /buildstream/sda3.img
    mkswap -L swap /buildstream/sda3.img

  partition-commands:
  - |
    ########################################
    #         Partition the disk           #
    ########################################

    # First get the size in bytes
    sda1size=$(stat -c "%s" /buildstream/sda1.img | head -c -1)
    sda2size=$(stat -c "%s" /buildstream/sda2.img | head -c -1)
    sda3size=$(stat -c "%s" /buildstream/sda3.img | head -c -1)

    # Now convert to sectors
    sda1sec=$(( ${sda1size} / %{sector-size} ))
    sda2sec=$(( ${sda2size} / %{sector-size} ))
    sda3sec=$(( ${sda3size} / %{sector-size} ))

    # Now get the offsets in sectors, first sector is MBR
    sda1offset=1
    sda2offset=$(( ${sda1offset} + ${sda1sec} ))
    sda3offset=$(( ${sda2offset} + ${sda2sec} ))

    # Get total disk size in sectors and bytes
    sdasectors=$(( ${sda3offset} + ${sda3sec} ))
    sdabytes=$(( ${sdasectors} * %{sector-size} ))

    # Create the main disk and do the partitioning
    truncate -s ${sdabytes} /buildstream/sda.img
    parted -s /buildstream/sda.img mklabel msdos
    parted -s /buildstream/sda.img unit s mkpart primary fat32 ${sda1offset} $(( ${sda1offset} + ${sda1sec} - 1 ))
    parted -s /buildstream/sda.img unit s mkpart primary ext2 ${sda2offset} $(( ${sda2offset} + ${sda2sec} - 1 ))
    parted -s /buildstream/sda.img unit s mkpart primary linux-swap ${sda3offset} $(( ${sda3offset} + ${sda3sec} - 1 ))

    # Make partition 1 the boot partition
    parted -s /buildstream/sda.img set 1 boot on

    # Now splice the existing filesystems directly into the image
    dd if=/buildstream/sda1.img of=/buildstream/sda.img \
        ibs=%{sector-size} obs=%{sector-size} conv=notrunc \
        count=${sda1sec} seek=${sda1offset}

    dd if=/buildstream/sda2.img of=/buildstream/sda.img \
        ibs=%{sector-size} obs=%{sector-size} conv=notrunc \
        count=${sda2sec} seek=${sda2offset}

    dd if=/buildstream/sda3.img of=/buildstream/sda.img \
        ibs=%{sector-size} obs=%{sector-size} conv=notrunc \
        count=${sda3sec} seek=${sda3offset}
  final-commands:
  - |
    # Move the image where it will be collected
    mv /buildstream/sda.img %{install-root}
    chmod 0644 %{install-root}/sda.img