RPi compiled code

[Tangerino]

My application runs seamlessly on macOS (for development purposes), Linux (for testing), and ESP32 (on actual devices) using the exact same codebase. For the ESP32, I compile the code into a .mpy file and utilize an OTA (Over-the-Air) system for distributing these files.

Now, I'm contemplating deploying this application on a Raspberry Pi. Can I maintain this portability? Specifically, I'm considering using mp-cross to compile and generate .mpy files tailored for the Raspberry Pi platform. Is this feasible? Directly deploying the source code isn't an option for me.

[rkompass]

Yes, course.
Note that the .mpy format is dependent on the architecture. You will have to specify another arch option for mpy-cross and keep the .mpy files separate.

[jimmo]

Note that the .mpy format is dependent on the architecture.

@rkompass This is only true if you are using native code in your .mpy file. Otherwise the same .mpy file will run on every supported MicroPython target.

@Tangerino Assuming you are not using the @native decorator, you should consider the Raspberry Pi to be no different to any other Linux. i.e. using the Linux port.

The Unix port is pretty limited for hardware/network support

The unix port has full network support, but yeah, limited hardware access. You can in theory access the UART via /dev/tty and a bit of stuffing around with termios, and GPIO via sysfs.

[Tangerino]

@rkompass That is the idea!!!

Micropython can compile to the following architectures

x86, x64, armv6, armv6m, armv7m, armv7em, armv7emsp, armv7emdp, xtensa, xtensawin

So, as of today, my understanding is that we can't compile for modern RPi devices. Right?

I have some devices and using lscpu I get

lscpu

Architecture:                    aarch64
CPU op-mode(s):                  32-bit, 64-bit
Model:                           4
Model name:                      Cortex-A53

and

Architecture:          armv7l
Byte Order:            Little Endian
CPU(s):                4
Model:                 4
Model name:            ARMv7 Processor rev 4 (v7l)

[rkompass]

@Tangerino:

import sys

sys_mpy = sys.implementation._mpy
print("arch: ", end='')
try:
    arch = [None, 'x86', 'x64', 'armv6', 'armv6m', 'armv7m', 'armv7em', 
        'armv7emsp', 'armv7emdp', 'xtensa', 'xtensawin'][sys_mpy >> 10]
    print(arch)
except:
    print('unknown')

gives me arch: armv6m on my modern RPi Pico W, and we can compile this.

[rkompass]

Did you mean an ordinary modern Raspberry Pi with Linux?
What does the above code snippet print when you run it in MP on such a device?

[scruss]

likely arch: armv6 on 32-bit Raspberry Pi OS and arch: None on 64-bit. The latter's going to be a problem for any native code. So @Tangerino's assertion that that we can't compile for modern RPi devices is correct, if running a 64-bit OS.

The Unix port is pretty limited for hardware/network support, so running it on a Raspberry Pi may be a disappointment.

[rkompass]

I noticed that without using @Tangerino there is no E-mail notification, when messages are appended this way (.?!).
So if you read that only now again: Would be interesting to know what the above code snippet does print when you run it in MP on your Raspi.
I found out that the arm8, which is 64 bit, may be switched to 32 bit mode, which apparently happens in Raspbian OS and I now think that you tried two versions of Linux: An original 32 bit Raspbian where that happens, and a 64 bit version.
Did you try Micropython on both versions?
It's just curiosity on my side. But would be good to know if MP runs there, what I strongly assume.
And from my limited understanding so far: If you have an architecture which it runs on then you should also get an info of the
processor architecture, that is used and mpy-cross should also work with that architecture. I would be surprised if it were otherwise.

[Tangerino]

First step was to compile using Debian 32 bits

Linux pi5 4.19.66-v7+ #1253 SMP Thu Aug 15 11:49:46 BST 2019 armv7l GNU/Linux

lscpu

Architecture:          armv7l
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    1
Core(s) per socket:    4
Socket(s):             1
Model:                 4
Model name:            ARMv7 Processor rev 4 (v7l)
CPU max MHz:           1200.0000
CPU min MHz:           600.0000
BogoMIPS:              38.40
Flags:                 half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32

It seems to start, since in my folder I have a main.py and bunch of .mpy files

I stuck on the crypto library so I need tweak my import policies.

So far so good but just saw the unix port does not support UART so this does not make sense anymore :(

Carlos

[scruss]

Would be interesting to know what the above code snippet does print when you run it in MP

That's what my output was: arch: armv6 on 32-bit Raspberry Pi OS (armhf) and arch: None on 64-bit (aarch64). Running on a Raspberry Pi 4 will currently give you a 64-bit kernel, even if you're running a 32-bit userland.

Tangerino's Linux installation is quite old, running a 4.x kernel. Current versions are 6.1.21 or so. Sounds like the lack of UART on the Unix port was a showstopper.

[rkompass]

Thank you, that makes sense. MP on the Raspberry Pi seems to be a bit neglected, as there is ordinary Python.

[Tangerino]

I need to use a more capable hardware in solar plants where we have hundreds of devices to monitor and sometimes 4 or more serial ports.

[rkompass]

Do you have a lot of data incoming fast?