[OpenWrt-Devel] SDK enhancement proposal - add external toolchains via feeds

[Jo-Philipp Wich]

Hello Mirko,

> Problem statement
> 
> To support new chipsets, it is sometimes necessary to work with
> vendor-specific toolchains. Until now, the process to add these
> toolchains to the build environment is a manual one. This leads
> companies to create their own automation scripts, creating a parallel SDK. 

can you elaborate a little bit on this manual process? I assume the
mentioned companies already utilize the CONFIG_EXTERNAL_TOOLCHAIN
feature in menuconfig but you intend to steamline the process of setting
related configuration symbols such as CONFIG_TARGET_NAME,
CONFIG_TOOLCHAIN_ROOT, CONFIG_TOOLCHAIN_BIN_PATH etc.?

> Proposed solution
> 
> We propose to extend the build system to enable the addition of external
> toolchains via feeds.

Do you intend to host the actual toolchain executables in such a feed or
just a set of configuration manifests to tie already installed host
toolchains into the buildroot?

Either variant does not align well with the existing feed concept which
basically represents a collection of build recipes organized in a directory.

The toolchain "repository" suggestion aims more into the direction of
buildroot configuration management so /maybe/ something interacting with
scripts/env to prime .config values with appropriate per-toolchain
settings would be a way forward, but first we need to better understand
the requirements.

> Benefit
> 
> This would remove the need for anyone to perform any manual steps or
> maintain their own script. Enabling their addition through feeds would
> streamline the way these toolchains are to be added and make removing
> them later in the development cycle almost transparent and therefore a
> lot less difficult.

Would it be possible for you to provide a more detailed description
regarding the typical manual steps required to hook an external
toolchain into OpenWrt? Are all require modifications strictly .config
changes or are modifications to Makefiles, scripts etc. required?

> Implementation proposal 
> 
> We propose to extend the scripts/feeds script and other parts of the
> build system to detect external toolchains in feeds and adds them
> accordingly.

As written above, the feeds infrastructure might not the place where the
feature should end up, but let us better understand the requirements first.

> Next steps
> 
> If there is support for the idea by the community, member companies of
> prpl start development and will propose a series of patches to this
> mailing list.

Sounds good to me.


Regards,
Jo

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