[RFC Patch v2] binman: add support for creating dummy files for external blobs

[Simon Glass]

Hi Heiko,

On Mon, 29 Nov 2021 at 02:48, Heiko Thiery <heiko.thiery at gmail.com> wrote:
>
> While converting to binman for an imx8mq board, it has been found that
> building in the u-boot CI fails. This is because an imx8mq requires an
> external binary (signed_hdmi_imx8m.bin). If this file cannot be found
> mkimage fails.
> To be able to build this board in the u-boot CI a binman option
> (--fake-ext-blobs) is introduced that can be switched on via the u-boot
> makefile option BINMAN_FAKE_EXT_BLOBS. With that the needed dummy files are
> created.
>
> Signed-off-by: Heiko Thiery <heiko.thiery at gmail.com>
> ---
> v2:
>  - pass allow_fake_blobs to ProcessImage()
>  - set AllowAllowFakeBlob() to images/entries
>  - create fake blob in Entry_blot.ObtainContents() when file is missing and
>    creation is allowed
>
>  still missing:
>   - unittest
>   - option to set BINMAN_FAKE_EXT_BLOBS in Makefile via environment
>         variable. With that we could simply set this env variable in the CI
>         (gitlab-ci.yml) with adding support to buildman.
>
>  Makefile                       |  1 +
>  tools/binman/cmdline.py        |  2 ++
>  tools/binman/control.py        |  9 +++++++--
>  tools/binman/entry.py          | 11 +++++++++++
>  tools/binman/etype/blob.py     |  7 +++++++
>  tools/binman/etype/blob_ext.py |  8 ++++++++
>  tools/binman/etype/mkimage.py  |  9 +++++++++
>  tools/binman/etype/section.py  |  9 +++++++++
>  8 files changed, 54 insertions(+), 2 deletions(-)

This looks good to me! The only thing is that instead of the warning
you should just print a single line at the end saying which blobs were
faked. See missing_list in ProcessImage() for how that could work. You
can set self.fake_blob in your blob.ObtainContents() and then have a
similar thing to CheckMissing() to actually collect the list of
entries which were faked.

Also, for the real version can you please add a test (so 'binman test
-T' stays at 100% test coverage) and some docs in binman.rst ? You can
use testMissingBlob() as a template.

Regards,
Simon