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assembler/qcow2: only require loopback for grub2

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Create and instantiate the ext4 filesystem directly on the device, without
ever mounting it. This means that only grub2 now requires loopback devices
to function properly.

Signed-off-by: Tom Gundersen <teg@jklm.no>
This commit is contained in:
Tom Gundersen 2019-07-11 00:03:34 +02:00 • committed by Lars Karlitski
parent a428572382
commit 7ea901928d
1 changed files with 14 additions and 10 deletions
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24
assemblers/io.weldr.qcow2
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@ -61,18 +61,22 @@ def main(tree, output_dir, options):
# Set up the partition table of the image
partition_table = "label: mbr\nlabel-id: {partition_table_id}\nbootable, type=83"
subprocess.run(["sfdisk", "-q", image], input=partition_table, encoding='utf-8', check=True)
r = subprocess.run(["sfdisk", "--json", image], stdout=subprocess.PIPE, encoding='utf-8', check=True)
partition_table = json.loads(r.stdout)
partition = partition_table["partitiontable"]["partitions"][0]
partition_offset = partition["start"] * 512
partition_size = partition["size"] * 512
# Populate the first partition of the image with an ext4 fs and fill it with the contents of the
# tree we are operating on.
subprocess.run(["mkfs.ext4", "-d", tree, "-U", root_fs_uuid, "-E", f"offset={partition_offset}", image, f"{int(partition_size / 1024)}k"], input="y", encoding='utf-8', check=True)
# Mount the created image as a loopback device
with loop_device(image, size) as loop:
# Populate the first partition of the image with an ext4 fs and fill it with the contents of the
# tree we are operating on.
subprocess.run(["mkfs.ext4", "-d", tree, "-U", root_fs_uuid, f"{loop}p1"], check=True)
# Install grub2 into the boot sector of the image
# It is unclear why chrooting into the image is required.
with mount(f"{loop}p1", mountpoint):
with mount_api(mountpoint):
subprocess.run(["chroot", mountpoint, "grub2-install", "--no-floppy", "--target", "i386-pc", loop], check=True)
with loop_device(image, size) as loop, \
mount(f"{loop}p1", mountpoint):
# Install grub2 into the boot sector of the image, and copy the grub2 imagise into /boot/grub2
with mount_api(mountpoint):
subprocess.run(["chroot", mountpoint, "grub2-install", "--no-floppy", "--target", "i386-pc", loop], check=True)
subprocess.run(["qemu-img", "convert", "-O" "qcow2", "-c", image, f"{output_dir}/{filename}"], check=True)