[Buildroot] [PATCH 2/6] boot/uboot: support building U-Boot with Python 3.x

Yann E. MORIN
2020-05-03T08:02:31Z

Thomas, All,

On 2020-05-02 23:28 +0200, Thomas Petazzoni spake thusly:
> U-Boot versions newer than 2020.01 use Python 3.x instead of Python
> 2.x in various scripts.
>
> We already had the BR2_TARGET_UBOOT_NEEDS_PYLIBFDT and
> BR2_TARGET_UBOOT_NEEDS_PYELFTOOLS options, but depending on the U-Boot
> version, we now need to indicate if Python 2.x or Python 3.x should be
> used.
>
> In addition, it turns out that some U-Boot configurations need a
> Python interpreter, without needing pylibfdt or pyelftools. Some of
> our defconfigs were abusing the BR2_TARGET_UBOOT_NEEDS_PYLIBFDT option
> to make sure a Python interpreter was built.
>
> To solve both issues, we add a new option
> BR2_TARGET_UBOOT_NEEDS_PYTHON, which itself has a choice to choose
> between Python 2.x and Python 3.x. It defaults to Python 2.x to
> preserve backward compatibility.
>
> The existing BR2_TARGET_UBOOT_NEEDS_PYLIBFDT and
> BR2_TARGET_UBOOT_NEEDS_PYELFTOOLS options select
> BR2_TARGET_UBOOT_NEEDS_PYTHON.
>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> ---
> boot/uboot/Config.in | 29 +++++++++++++++++++++++++++++
> boot/uboot/uboot.mk | 12 +++++++++++-
> 2 files changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/boot/uboot/Config.in b/boot/uboot/Config.in
> index 7a6f5053fd..e10166a113 100644
> --- a/boot/uboot/Config.in
> +++ b/boot/uboot/Config.in
> @@ -147,14 +147,43 @@ config BR2_TARGET_UBOOT_NEEDS_DTC
> Select this option if your U-Boot board configuration
> requires the Device Tree compiler to be available.
>
> +config BR2_TARGET_UBOOT_NEEDS_PYTHON
> + bool "U-Boot needs host Python"
> +
> +if BR2_TARGET_UBOOT_NEEDS_PYTHON
> +
> +choice
> + prompt "Python version"
> + default BR2_TARGET_UBOOT_NEEDS_PYTHON2
> +
> +config BR2_TARGET_UBOOT_NEEDS_PYTHON2
> + bool "python 2.x"
> + help
> + Select this option if U-Boot needs a host Python 2.x
> + interpreter. This is the case for some U-Boot
> + configurations, prior to U-Boot 2020.01.
> +
> +config BR2_TARGET_UBOOT_NEEDS_PYTHON3
> + bool "python 3.x"
> + help
> + Select this option if U-Boot needs a host Python 3.x
> + interpreter. This is the case for some U-Boot
> + configurations, after U-Boot 2020.01.
> +
> +endchoice

I don't like it much that construct, where a boolean hides a choice.
Instead, we can siumply use a choice (options names abbreviated as I'm
lazy to type them full):

choice
"Python support needed"

config UBOOT_PY_NONE
"none"

config UBOOT_PY2
"python2"

config UBOOT_PY3
"python3"

endchoice

> +endif
> +
> config BR2_TARGET_UBOOT_NEEDS_PYLIBFDT
> bool "U-Boot needs pylibfdt"
> + select BR2_TARGET_UBOOT_NEEDS_PYTHON
> help
> Select this option if your U-Boot board configuration
> requires the Python libfdt library to be available.
>
> config BR2_TARGET_UBOOT_NEEDS_PYELFTOOLS
> bool "U-Boot needs pyelftools"
> + select BR2_TARGET_UBOOT_NEEDS_PYTHON

Of course here (both pylibfdt and pyelftools), you'd have to switch to a
depends-on, but that does not change much afterall.

Regards,
Yann E. MORIN.

> help
> Select this option if your U-Boot board configuration
> requires the Python pyelftools library to be available.
> diff --git a/boot/uboot/uboot.mk b/boot/uboot/uboot.mk
> index 7bd9cbae52..1d50e72846 100644
> --- a/boot/uboot/uboot.mk
> +++ b/boot/uboot/uboot.mk
> @@ -159,12 +159,22 @@ ifeq ($(BR2_TARGET_UBOOT_NEEDS_DTC),y)
> UBOOT_DEPENDENCIES += host-dtc
> endif
>
> +ifeq ($(BR2_TARGET_UBOOT_NEEDS_PYTHON2),y)
> +UBOOT_DEPENDENCIES += host-python
> +else ifeq ($(BR2_TARGET_UBOOT_NEEDS_PYTHON3),y)
> +UBOOT_DEPENDENCIES += host-python3
> +endif
> +
> ifeq ($(BR2_TARGET_UBOOT_NEEDS_PYLIBFDT),y)
> -UBOOT_DEPENDENCIES += host-python host-swig
> +UBOOT_DEPENDENCIES += host-swig
> endif
>
> ifeq ($(BR2_TARGET_UBOOT_NEEDS_PYELFTOOLS),y)
> +ifeq ($(BR2_TARGET_UBOOT_NEEDS_PYTHON2),y)
> UBOOT_DEPENDENCIES += host-python-pyelftools
> +else ifeq ($(BR2_TARGET_UBOOT_NEEDS_PYTHON3),y)
> +UBOOT_DEPENDENCIES += host-python3-pyelftools
> +endif
> endif
>
> ifeq ($(BR2_TARGET_UBOOT_NEEDS_OPENSSL),y)
> --
> 2.26.2
>
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