Re: [Xen-devel] [RFC 3/7] linux-stubdomain: Build a disk image

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 3 Feb 2015, Eric Shelton wrote:
> This patch builds a disk image intended to be mounted as rootfs by the
> Linux stub domain.  It is assembled using dracut and genext2fs.
> 
> Signed-off-by: Eric Shelton <eshelton@xxxxxxxxx>
> ---
>  stubdom-linux/.gitignore          |  4 ++
>  stubdom-linux/Makefile            | 45 +++++++++++++++++++-
>  stubdom-linux/extra/initscript    | 25 +++++++++++
>  stubdom-linux/extra/qemu-ifup     |  7 +++
>  stubdom-linux/gen-stubdom-disk.sh | 89 
> +++++++++++++++++++++++++++++++++++++++
>  5 files changed, 168 insertions(+), 2 deletions(-)
>  create mode 100644 stubdom-linux/extra/initscript
>  create mode 100644 stubdom-linux/extra/qemu-ifup
>  create mode 100755 stubdom-linux/gen-stubdom-disk.sh
> 
> diff --git a/stubdom-linux/.gitignore b/stubdom-linux/.gitignore
> index 891f0c8..b8f2e26 100644
> --- a/stubdom-linux/.gitignore
> +++ b/stubdom-linux/.gitignore
> @@ -4,3 +4,7 @@
>  /linux-*.tar.xz
>  /linux-*/
>  /vmlinuz-stubdom
> +/initramfs
> +/stubdom-disk.img
> +/dracut-???*
> +/genext2fs-*
> diff --git a/stubdom-linux/Makefile b/stubdom-linux/Makefile
> index 31bfbee..a46f5b0 100644
> --- a/stubdom-linux/Makefile
> +++ b/stubdom-linux/Makefile
> @@ -12,7 +12,19 @@ LINUX_V=linux-3.17.8
>  VMLINUZ=$(LINUX_V)/arch/x86/boot/bzImage
>  LINUX_URL=ftp://ftp.kernel.org/pub/linux/kernel/v3.x/$(LINUX_V).tar.xz
>  
> -all: $(VMLINUZ)
> +DRACUT_URL="http://www.kernel.org/pub/linux/utils/boot/dracut";
> +DRACUT_V=dracut-033
> +
> +GENEXT2FS_V = 1.4.1
> +GENEXT2FS_URL="http://sourceforge.net/projects/genext2fs/files/genext2fs/$(GENEXT2FS_V)/genext2fs-$(GENEXT2FS_V).tar.gz/download"

I don't think that we need to download install these tools. They are
available on all major distros.
I think we could add them as dependency to the xen-unstable configure
script.


> +# Stubdom disk content
> +STUBDOM_DISK_FILE= \
> +  qemu-build/i386-softmmu/qemu-system-i386 \
> +  extra/initscript \
> +  extra/qemu-ifup
> +
> +all: $(VMLINUZ) stubdom-disk.img
>  
>  qemu-build/Makefile:
>       export GIT=$(GIT); \
> @@ -73,5 +85,34 @@ $(LINUX_V)/Makefile $(LINUX_V)/.config: $(LINUX_V).tar.xz
>  $(VMLINUZ): $(LINUX_V)/.config
>       $(MAKE) -C $(LINUX_V)
>  
> -install: $(VMLINUZ)
> +$(DRACUT_V).tar.xz:
> +     $(FETCHER) $@ $(DRACUT_URL)/$@
> +
> +DRACUT_INSTALL=$(CURDIR)/$(DRACUT_V)/dracut-install
> +$(DRACUT_INSTALL): $(DRACUT_V).tar.xz
> +     tar xf $<
> +     $(MAKE) -C $(DRACUT_V) dracut-install
> +
> +GENEXT2FS = $(shell which genext2fs 2>/dev/null)
> +ifeq ($(GENEXT2FS),)
> +GENEXT2FS = $(CURDIR)/genext2fs-$(GENEXT2FS_V)/genext2fs
> +endif
> +
> +genext2fs-$(GENEXT2FS_V).tar.gz:
> +     $(FETCHER) $@ $(GENEXT2FS_URL)
> +$(CURDIR)/genext2fs-$(GENEXT2FS_V)/genext2fs: genext2fs-$(GENEXT2FS_V).tar.gz
> +     tar xf $<
> +     cd genext2fs-$(GENEXT2FS_V) && ./configure
> +     $(MAKE) -C genext2fs-$(GENEXT2FS_V)
> +
> +gen-stubdom-disk.sh: $(DRACUT_INSTALL) $(GENEXT2FS)
> +
> +export DRACUT_INSTALL
> +export GENEXT2FS
> +stubdom-disk.img: gen-stubdom-disk.sh $(STUBDOM_DISK_FILE)
> +     env -u MAKELEVEL -u MAKEFLAGS -u MFLAGS ./$<
> +     chmod a-w $@
> +
> +install: $(VMLINUZ) stubdom-disk.img
>       cp -f $(VMLINUZ) $(DESTDIR)/usr/local/lib/xen/boot/vmlinuz-stubdom
> +     cp -f stubdom-disk.img $(DESTDIR)/usr/local/lib/xen/boot/
> diff --git a/stubdom-linux/extra/initscript b/stubdom-linux/extra/initscript
> new file mode 100644
> index 0000000..a0f50ad
> --- /dev/null
> +++ b/stubdom-linux/extra/initscript
> @@ -0,0 +1,25 @@
> +#!/bin/busybox sh
> +
> +set -e
> +set -x
> +mount -t sysfs /sys /sys
> +mount -t proc /proc /proc
> +mount -t xenfs -o nodev /proc/xen /proc/xen
> +
> +if test -e /sys/class/net/eth0; then
> +  ip link set eth0 address fe:ff:ff:ff:ff:fe
> +  ip addr flush eth0
> +  ip link set eth0 up
> +  brctl addbr br0
> +  brctl addif br0 eth0
> +  ip link set br0 up
> +else
> +  echo "No network interface named eth0."
> +  ls -l /sys/class/net/
> +fi
> +
> +domid=$(/bin/xenstore-read "target")
> +vm_path=$(xenstore-read "/local/domain/$domid/vm")
> +dm_args=$(xenstore-read "$vm_path/image/dmargs")
> +
> +/bin/qemu $dm_args
> diff --git a/stubdom-linux/extra/qemu-ifup b/stubdom-linux/extra/qemu-ifup
> new file mode 100644
> index 0000000..d71672b
> --- /dev/null
> +++ b/stubdom-linux/extra/qemu-ifup
> @@ -0,0 +1,7 @@
> +#! /bin/busybox sh
> +
> +ip link set "$1" down
> +ip link set "$1" address fe:ff:ff:ff:ff:fd
> +ip addr flush "$1"
> +brctl addif br0 "$1"
> +ip link set "$1" up
> diff --git a/stubdom-linux/gen-stubdom-disk.sh 
> b/stubdom-linux/gen-stubdom-disk.sh
> new file mode 100755
> index 0000000..c209cba
> --- /dev/null
> +++ b/stubdom-linux/gen-stubdom-disk.sh
> @@ -0,0 +1,89 @@
> +#!/bin/bash
> +
> +set -e
> +umask 022
> +
> +script_qemu_ifup="extra/qemu-ifup"
> +script_init="extra/initscript"
> +
> +XEN_ROOT="$(cd ..; pwd)"
> +xenstore_libs="$XEN_ROOT/tools/xenstore"
> +libxc_libs="$XEN_ROOT/tools/libxc"
> +export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$xenstore_libs"
> +export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$libxc_libs"
> +
> +initdir="`pwd`/initramfs/"
> +
> +rm -fr "$initdir"
> +
> +# Using dracut to gather the shared libraries
> +# from https://dracut.wiki.kernel.org/index.php/Main_Page
> +if ! test -x "$DRACUT_INSTALL"; then
> +  echo DRACUT_INSTALL unset or incorrect >&2
> +  exit 1
> +fi
> +if ! test -x "$GENEXT2FS"; then
> +  if ! which genext2fs 2>&1 >/dev/null; then
> +    echo genext2fs not found and GENEXT2FS unset >&2
> +    exit 1
> +  fi
> +else
> +  function genext2fs(){
> +    "$GENEXT2FS" "$@"
> +  }
> +fi
> +
> +
> +inst() {
> +    [[ -e "${initdir}/${2:-$1}" ]] && return 0  # already there
> +    "$DRACUT_INSTALL" -D "$initdir" -l "$@"
> +}
> +
> +mkdir -p "$initdir"/{bin,etc,proc/xen,sys,lib,dev,tmp}
> +
> +echo "Building initrd in $initdir"
> +inst busybox /bin/busybox
> +make DESTDIR="$initdir" -C qemu-build install
> +# this gather libs install on the system for qemu
> +inst "$initdir/bin/qemu-system-i386" /bin/qemu
> +inst "$XEN_ROOT/tools/xenstore/xenstore-read" "/bin/xenstore-read"
> +inst "$script_qemu_ifup" "/etc/qemu-ifup"
> +chmod +x "$initdir/etc/qemu-ifup"
> +inst "$script_init" "/init"
> +chmod 755 "$initdir/init"
> +
> +ln -s busybox "$initdir/bin/mount"
> +
> +for d in "/usr/lib" "$xenstore_libs" "$libxc_libs"; do
> +  d="$initdir/$d"
> +  if test -d "$d"; then
> +    mv "$d"/* "$initdir/lib64/"
> +    if test -L "$d"; then
> +      rm "$d"
> +    else
> +      rmdir --ignore-fail-on-non-empty -p "$d"
> +    fi
> +  fi
> +done
> +
> +mv "$initdir/lib64/gcc"/*/*/* "$initdir/lib64/"
> +rm -rf "$initdir/lib64/gcc"
> +
> +mkdir -p "$initdir/usr"
> +ln -s /lib "$initdir/usr/lib"
> +
> +if false; then
> +  IMAGE="./initramfs.cpio"
> +  rm -f "$IMAGE"
> +  (cd "$initdir"; find . | cpio -H newc --quiet -o) >| "$IMAGE" || exit 1
> +  gzip -f "$IMAGE"
> +else # ext2 fs using:
> +  stubdom_disk=stubdom-disk.img
> +  rm -f "$stubdom_disk"
> +  genext2fs \
> +    --root "$initdir" \
> +    --size-in-blocks $(($(du -s "$initdir"|cut -f1)+2000)) \
> +    --reserved-percentage 0 \
> +    --squash \
> +    "$stubdom_disk"
> +fi
> -- 
> 1.8.5.5
> 

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