Severin Teona - SAOC Milestone 1 Update 2 - Druntime for Microcontrollers

[kinke]

On Wednesday, 30 September 2020 at 16:35:05 UTC, Severin Teona 
wrote:
> 1. During the installation, because I was using 
> ‘arm-none-eabi-gcc’, I got the following messages:
>
> — The C compiler identification is GNU 9.3.1
> — Detecting C compiler ABI info
> — Detecting C compiler ABI info - failed
> — Detecting C compile features
> — Detecting C compile features - done
> — The ASM compiler identification is GNU
> — Found assembler: 
> /home/teona/gcc-arm-none-eabi-9-2020-q2-update/bin/arm-none-eabi-gcc
> — Looking for sys/types.h
> — Looking for sys/types.h - not found
> — Looking for stdint.h
> — Looking for stdint.h - not found
> — Looking for stddef.h
> — Looking for stddef.h - not found
> — Check size of void*
> — Check size of void* - failed
> — Looking for unistd.h
> — Looking for unistd.h - not found
> — Configuring done
> — Generating done
>
> Both the build and the linking parts were succesful, but I 
> wanted to ask you if I should care about those messages, or if 
> they appear because I wasn’t using ‘gcc’.

Seems okay for the moment, although the failing `size of void*` 
test certainly isn't ideal (IIRC, we make use of it in the CMake 
script). But no need to worry for now if things seem to be 
working.

> 2. Also, I tried building the runtime without 
> ‘BUILD_SHARED_LIBS=OFF’ and it failed, as it was looking for 
> some dynamic libraries (-lpthread, -ldl, -lrt, and so on). My 
> question here is, does abynody here know if there exists a set 
> of dynamic libraries, compiled for this architecture? With 
> TockOS, I’ve been using newlib([2]) as C standard library, but 
> newlib is a static library. Would it make a big difference if I 
> used a dynamic library?

I strongly suggest not caring about the shared druntime/Phobos 
libs for now, those introduce lots of complexity, especially wrt. 
TLS, so focus on the static libs first (or even exclusively).

> My plan for next week is:
> - to try to emulate a Cortex-M4 device using qemu - the biggest 
> issue I have here is that there are just 2 Cortex-M4 based 
> devices that can be emulated, and the resources(64KB of RAM and 
> 256KB of flash) are way smaller than what I need (>2.5MB flash 
> - the current size of the compiled runtime).

I'm definitely no qemu expert, but are you sure you can't use the 
generic `virt` machine via something like `-M virt -m 1024 -cpu 
cortex-m4`?

For reference, here's what I use for emulating AArch64 (on a 
Windows host), giving it 3 cores and 6 GB of RAM:

"C:\Program Files\qemu\qemu-system-aarch64" -M virt -m 6144 -cpu 
cortex-a57 -smp 3 -kernel vmlinuz -initrd initrd.img -append 
"root=/dev/vda1" -drive if=none,file=disk.raw,format=raw,id=hd 
-device virtio-blk-device,drive=hd -netdev 
user,id=mynet,hostfwd=tcp::2222-:22 -device 
virtio-net-device,netdev=mynet