[actions] rpi changes

[dimitre]

This PR intends to fix RPI github actions
[hopefully] modernizing and fixing cross compiling issues
it replaces compilers installed via ci.openframeworks.cc with apt installable ones (and cached via github actions)

Status:

• aarch64 emptyexample
• aarch64 alladdonsexample
• armv6l emptyexample
• armv6l alladdonsexample

Errors - all fixed:
~~Using armv6l actions it doesnt find <bcm_host.h>, it is not installable via firmware.zip anymore.
Maybe it is possible to install via apt packages, have to research more about this one.

aarch64 alladdonsexample linking errors:

/usr/lib/gcc-cross/aarch64-linux-gnu/11/../../../../aarch64-linux-gnu/bin/ld: warning: liblapack.so.3, needed by /home/runner/work/openFrameworks/openFrameworks/scripts/ci/linuxrpi/raspbian/usr/lib/aarch64-linux-gnu/libopencv_core.so, not found (try using -rpath or -rpath-link)
/usr/lib/gcc-cross/aarch64-linux-gnu/11/../../../../aarch64-linux-gnu/bin/ld: warning: libblas.so.3, needed by /home/runner/work/openFrameworks/openFrameworks/scripts/ci/linuxrpi/raspbian/usr/lib/aarch64-linux-gnu/libopencv_core.so, not found (try using -rpath or -rpath-link)
/home/runner/work/openFrameworks/openFrameworks/scripts/ci/linuxrpi/raspbian/usr/lib/aarch64-linux-gnu/libm.a(s_sin.o): in function `__sin':
(.text+0x10): relocation truncated to fit: R_AARCH64_LD64_GOTPAGE_LO15 against symbol `__stack_chk_guard@@GLIBC_2.17' defined in .data.rel.ro section in /home/runner/work/openFrameworks/openFrameworks/scripts/ci/linuxrpi/raspbian/lib/ld-linux-aarch64.so.1
/usr/lib/gcc-cross/aarch64-linux-gnu/11/../../../../aarch64-linux-gnu/bin/ld: (.text+0x10): warning: too many GOT entries for -fpic, please recompile with -fPIC
collect2: error: ld returned 1 exit status

~~

[dimitre]

Hello @ofTheo @danoli3 @artificiel can you help with some ideas for this one?

[artificiel]

not in a Pi position right now but for bcm_host.h if these changes have implications that go "way back", a few years ago it became necessary to install libraspberrypi-dev and maybe raspberrypi-kernel-headers to get things in general to compile.

[dimitre]

Thanks. for what I've seen there are some headers in this repo / folder
https://github.com/raspberrypi/userland
host_applications/linux/libs/bcm_host/include

[ofTheo]

@dimitre - I'll have a look!
I think I tried doing things without firmware.zip and ran into the same issues with bcm_host.h

[artificiel]

for liblaplack (CV dependency), is liblapack-dev already in there?

depending on how deep you want to dig maybe it's simpler to keep the old pre-packaged toolchain for armv6 and your updated approach from aarch64?

[dimitre]

I suggest we drop armv6l architecture since aarch64 will run in most RPI versions including
Pi Zero 2
Pi 3
Pi 4
Pi 5

[dimitre]

bcm_host.h solved and other fixes. it is finishing compilation here locally,
still issues on allAddons, only a matter of passing the correct library paths I think

[dimitre]

Great! everything good with allAddons in all platforms.
I'll be tidying up for merging. any objections?

[ofTheo]

Will this work for people working with the device itself ( as opposed to building in the CI )?
ie: does userland exist for Pi device users?

[dimitre]

Good catch. maybe I should put back the includes with /opt/vc in armv6l
easy to do

[dimitre]

and enclose this in ifdef CROSS_COMPILE

[ofTheo]

congrats @dimitre !!
ooof - that was a gnarly one.