Re: I like to add arm-none-eabi support to crosstool-ng

[Erico Nunes <nunes dot erico at gmail dot com>]

Hi Jasmin,

On Thu, Aug 27, 2015 at 8:44 PM, Jasmin J. <jasmin@anw.at> wrote:
> Now I want to add the required configuration for arm-none-eabi. This GCC
> version is developed on a branch
>   https://gcc.gnu.org/svn/gcc/branches/ARM/embedded-4_9-branch/

As I understand, a toolchain for the arm-none-eabi target could just
be built from the regular gcc releases, and not only from the
"embedded" gcc branch, couldn't it?
Then how to use specific gcc branches to build a toolchain is a
different (and broader) question.

Doesn't the arm-unknown-eabi sample fit your requirements?

> To enable custom, it is required to enable EXPERIMENTAL. custom will enable
> CC_GCC_latest and this will enable CC_GCC_5_1_or_later.
> Because the ARM embedded GCC is a 4.9.x variant, it requires CLooG and this is
> not built for GCC 5.1.x.

This seems like a bug to me, I don't think you shouldn't be forced to
use 5.1 or later by having enabled EXPERIMENTAL.
Can you please re-test it with i.e. crosstool-ng 1.20 ? If it is a
regression, please file an Issue in
https://github.com/crosstool-ng/crosstool-ng .

> There are now several possibilities.
> 1)
> i-  I can add a new configuration similar to GCC_SHOW_LINARO for the ARM
>     embedded versions and pack my own arm-embedded GCC tarballs and post them
>     on sourceforge.net or somewhere else (e.g. gcc-4.9-arm-224057.tar.bz2).
> ii- Then I define the supported GCC version in the config (e.g.
>     CC_GCC_V_arm_embedded_4_9_<svn-number> and then I need to add arm_embedded
>     to 100-gcc.sh. And maybe more, which I will discover ;)
>
> 2)
> i-  See above.
> ii- I add an configuration, which opens a complete free gcc configuration with
>     gcc version, tar-name, download location, and the GCC version flags (e.g.
>     CC_GCC_4_9, CC_GCC_4_8, ... ).
>
> 3)
> i-  I make a new configuration option when custom is selected to select the
>     GCC version flag (e.g. CC_GCC_4_9, CC_GCC_4_8, ... ) and get rid of the
>     hard coded CC_GCC_latest (which would be still the default).

Is your intention to provide a configuration for arm-none-eabi only,
or one that uses the "embedded" gcc branch?
If it is the former and arm-unknown-eabi doesn't meet your needs, I
guess that providing a sample which builds for the arm-none-eabi
target with just the regular gcc release could be a nice start.

For the latter, I believe that the best option would be to make
crosstool-ng support remote repositories to be cloned and used for the
build, similar to what Buildroot does with 'git' and 'svn' download
methods for sources.
I too have missed this feature at least once, to distribute a
configuration which uses a custom remote source in a format more
portable than a path to a local directory (from my machine).

> What is the recommended procedure to achieve what I like to do an which will
> be accepted as patch?

You should follow the github flow and submit a pull request in:
https://github.com/crosstool-ng/crosstool-ng

Erico

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