Re: [PATCH v2 09/10] fdtfactor: Support compressed DTB inputs and outputs

[Simon Glass]

On 2026-10-28T21:46:49, Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
> fdtfactor: Support compressed DTB inputs and outputs
>
> Firmware and FIT image build pipelines frequently store device tree
> blobs compressed with LZ4, LZMA/XZ, or gzip (e.g., `.dtb.lz4`).
>
> Extend `fdtfactor` to detect compressed input blobs by magic bytes or
> file extension, transparently decompress them before factoring, and
> compress the resulting `.dtbo` and `base.dtb` outputs when appropriate:
>
> - Support `.lz4` (including legacy `-l` frames via the `lz4` CLI),
>   `.lzma`/`.xz` (via Python's `lzma` module, using `CHECK_CRC32` for XZ
>   compatibility with kernel/bootloader decompressors), and `.gz` (via
>   Python's `gzip` module).
> - Preserve the input compression format on generated `.dtbo` files and
>   compress `base.dtb` according to `--base-compression` (which defaults
>   to `auto`, auto-detecting from `--base-dtb`'s filename extension such
>   as `-b base.dtb.lz4`).
> - Report compressed size savings alongside uncompressed savings when
>   `-s`/`--stats` is specified.
>
> On the 47 Qualcomm SC7180 Trogdor Chromebook `.dtb.lz4` files,
> `fdtfactor -S` reduces total LZ4-compressed size from 1.71 MB to 213 KB
> (87.5% savings).
>
> Assisted-by: Gemini:gemini-pro-prerelease
> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
>
>  README.md            |  17 ++-
>  fdtfactor            | 312 +++++++++++++++++++++++++++++++++++++++++++++++----
>  tests/Makefile.tests |   5 +-
>  tests/run_tests.sh   |  77 ++++++++++++-
>  4 files changed, 379 insertions(+), 32 deletions(-)

Reviewed-by: Simon Glass <sjg@xxxxxxxxxxxx>