eva-image-tool

Parser, builder, and CLI for the Fritz!Box EVA kernel image format — the TI record container used by AVM's EVA bootloader to hold LZMA-compressed Linux kernels. Pure Python standard library, zero runtime dependencies.

See docs/format-spec.md for the full format specification and docs/format-quickref.md for a one-page summary.

Install

pipx install eva-kernel-image     # recommended for CLI-only use
pip  install eva-kernel-image     # for library use

No external binaries required — everything runs on Python's stdlib lzma, zlib, struct, and argparse.

CLI quickstart

# Inspect an image
eva-image info kernel.image

# Verify checksums (exit 0 if valid, non-zero otherwise)
eva-image verify kernel.image

# Extract kernels + metadata.json to a directory
eva-image extract kernel.image -o extracted/

# Rebuild an image, optionally replacing kernel(s)
eva-image repack kernel.image -o new.image
eva-image repack kernel.image -o new.image \
    --kernel1 patched-primary.bin

# Pack an image from raw kernel binaries
eva-image pack -o new.image \
    --kernel1 kernel1.bin --load1 0x80500000 --entry1 0x80C8B500 \
    --kernel2 kernel2.bin --load2 0x8DFFFFFC --entry2 0x8E691770

Library quickstart

from pathlib import Path
from eva_kernel_image import parse_image, build_image

image = parse_image(Path("kernel.image").read_bytes())

print(f"dual-kernel: {image.dual_header is not None}")
print(f"primary entry: 0x{image.primary.entry_addr:08X}")
print(f"primary uncompressed size: {image.primary.lzma.uncompressed_len}")

# Validate checksums (parser itself does not auto-validate)
for issue in image.validate():
    print(f"warning: {issue}")

# Decompress a kernel
Path("kernel1.bin").write_bytes(image.primary.decompress())

# Replace a kernel and rebuild
image.primary.replace_kernel(Path("patched.bin").read_bytes())
Path("patched.kernel.image").write_bytes(build_image(image))

Supported models

Verified against 18 reference images spanning six product lines:

Both single-kernel (FEED1281) and dual-kernel (FEED9112) variants are handled, including the legacy inner-signature quirk found on older Fritz!Box 7560 and 7580 builds.

License

see LICENSE.