Re: How to configure GNAT GPL on x86-64 Linux for ARM ELF development

[Adam Jensen <hanzer@riseup.net>]

On Wed, 23 May 2018 09:07:51 +0100, Simon Wright wrote:

> Adam Jensen <hanzer@riseup.net> writes:
> 
>> $ arm-eabi-gcc -c -mcpu=cortex-m4 -mthumb program.adb fatal error,
>> run-time library not installed correctly cannot locate file system.ads
>> compilation abandoned
> 
>> Any advice on how to proceed would be very much appreciated!
> 
> I think that the reason why the tutorial works and your attempt doesn't
> is that the tutorial was developed on a Raspberry Pi, which is already
> an ARM-based machine, so the native compiler actually has a runtime
> (i.e. system.ads etc etc) visible to it.
> 
> Yours doesn't, and gcc-for-ada must see an RTS.
> 
> I managed to get a compilation using this over-the-top incantation:
> 
>    $ gprbuild -c -u -f program.adb --target=arm-eabi --RTS=zfp-stm32f4
> 

Many thanks, this works! I do not yet know why it works - what it is 
doing - but the hint is a valuable. It occurred to me that I should be 
looking for Adacore documentation. I have yet to find a "getting started" 
tutorial for embedded development aimed at scientists, engineers and 
other technically mature people (ideally, such a tutorial would be 
comprehensive, to the point, and regularly tested), but I did find:

GPRbuild and GPR Companion Tools User’s Guide
<https://docs.adacore.com/gprbuild-docs/html/gprbuild_ug.html>

and

GNAT User’s Guide Supplement for Cross Platforms
<http://docs.adacore.com/live/wave/gnat_ugx/html/gnat_ugx/gnat_ugx.html>

By mining these two documents it might be possible to extract a basic 
explanation for these very first steps of the embedded development 
process.

It is curious that the Ada technology's utilization of the system 
engineering approach has not [yet] been extended into the pedagogical 
component. After all, software development is a very human-centric 
process.

But I digress. Thanks again for the guidance! After extracting the basics 
of project management from the core documentation, I hope to find a build 
process that enables the use of a Ravenscar profile. And after that I 
hope to configure the development environment to include Spark process 
components in the real-time embedded system. Does this seem reasonable? 
 

> but a simpler (more memorable!) procedure might be to construct your
> own:
> 
> 1. Create directories adainclude/, adalib/
> 
> 2. Copy $prefix/arm-eabi/lib/gnat/zfp-stm32f4/gnat/system.ads to your
>    adainclude/ ($prefix is the root of your compiler installation, I
>    think ~/.local/gnat-arm)
> 
> The zfp- (zero footprint) runtime is the closest to what you need, and
> the fact that the -stm32f4 part isn't quite right shouldn't matter; I
> suspect that system.ads is the same for all the zfp runtimes.
> 
> Now,
> 
>    $ arm-eabi-gcc --RTS=. -c program.adb