lokki not sure if the binary i installed is the reason for this. will try to compile the fat1.lv2 from source to see if it makes a difference

SIGILL (ILLEGAL INSTRUCTION) could happen if the binary was built for a different architecture, e.g.: an armv8 32bit binary will load but may fail on an instruction not present in armv7 (e.g.: NEON divide). If the binary is for armv7 then you could get a SIGILL because of some weird pointer error where you are trying to execute a portion of memory that does not contain executable data. I thought you had tried to compile the plugin yourself earlier? Where is the release from? Cannot see it on their github. You can try and run jalv inside gdb ( you'd do gdb jalv and then once you are in dorun < command line options> then when it fails you can see where (what function or even what line perhaps) it failed. You can also do disass to see the assembly and individuate the culprit instruction.

      giuliomoro got one step further. when i build the plugin without any optimisations, it runs. i get a ton of underruns, so i will now add in optimisations too see when it starts to fail :-)

        do you see a problematic one?:

        OPTIMIZATIONS="-Wall -Wno-unused-function -O3 -ffast-math -fomit-frame-pointer -fno-finite-math-only -fvisibility=hidden -fdata-sections -ffunction-sections -DNDEBUG -mfpu=neon-vfpv4 -mfloat-abi=hard -mvectorize-with-neon-quad"

        ok, with just -O3 -DNDEBUG it runs (i think)

        i get:

        root@bela:~/Bela/projects/jalv-Bela/build#  ./jalv http://gareus.org/oss/lv2/fat1
Plugin:       http://gareus.org/oss/lv2/fat1
UI:           None
Plugin requires 1 inputs and 1 outputs
Sample rate:  44100 Hz
Block length: 64 frames
MIDI buffers: 4096 bytes
Comm buffers: 65536 bytes
Update rate:  25.0 Hz

Plugin requires 1 inputs and 1 outputs
mode      = 0.000000
channelf  = 0.000000
tuning    = 440.000000
bias      = 0.500000
filter    = 0.100000
corr      = 1.000000
offset    = 0.000000
bendrange = 2.000000
fastmode  = 0.000000
m00       = 1.000000
m01       = 1.000000
m02       = 1.000000
m03       = 1.000000
m04       = 1.000000
m05       = 1.000000
m06       = 1.000000
m07       = 1.000000
m08       = 1.000000
m09       = 1.000000
m10       = 1.000000
m11       = 1.000000
nmask     = 0.000000
nset      = 0.000000
bend      = 0.000000
error     = 0.000000
latency   = 0.000000

        i can change the settings via the prompt. :-)

          and i can hear my voice!! yes.

          lokki the > at the end is not visible in the code section somehow, i take it this is some kind of prompt for the plugin

          yeah, never understood what you can do with it, but it's there at the bottom of jalv the whole time. What's the CPU like? Note that if there is a "worker thread", that will not show up at /proc/xenomai/sched/stat (because it wouldn't be a Xenomai task, as it is managed by jalv or the plugin itself), and you will have to do

          top -p `pidof jalv` -H

          to see the CPU usage of all the Linux threads (this will be percentage where the total available is 100 minus the sum of what is returned by /proc/xenomai/sched/stat.

            the ">" is to change the settings. if i type m10 = 0 for example it changes that parameter in the plugin. so it is a primitive UI :-)

            CPU:

            top:

            top - 23:39:20 up 49 min,  2 users,  load average: 0.52, 0.66, 0.64
Threads:   4 total,   0 running,   4 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.0 us,  0.3 sy,  0.0 ni, 99.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :   501464 total,   233488 free,    79792 used,   188184 buff/cache
KiB Swap:        0 total,        0 free,        0 used.   374764 avail Mem 

  PID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND                                                                            
 6088 root      20   0   22532  19412   7336 S  0.3  3.9   0:00.05 jalv                                                                               
 6090 root     -51   0   22532  19412   7336 S  0.3  3.9   0:00.14 bela-midiIn_hw:                                                                    
 6085 root      20   0   22532  19412   7336 S  0.0  3.9   0:00.38 jalv                                                                               
 6094 root     -96   0   22532  19412   7336 S  0.0  3.9   0:00.00 bela-audio

            xenomai stat:

            Every 0.5s: cat /proc/xenomai/sched/stat                                                                                 bela: Tue Dec 17 23:40:32 2019

CPU  PID    MSW        CSW        XSC        PF    STAT       %CPU  NAME
  0  0      0          658918     0          0     00018000   77.6  [ROOT]
  0  6085   3          4          13         0     000600c0    0.0  jalv
  0  6090   2          3          4          0     000480c0    0.0  bela-midiIn_hw:0,0,0
  0  6094   1          137640     137642     0     00048046   22.1  bela-audio
  0  0      0          315535     0          0     00000000    0.0  [IRQ16: [timer]]
  0  0      0          137647     0          0     00000000    0.2  [IRQ180: rtdm_pruss_irq_irq]

              oh. so there is no worker thread, or it's doing very little (it would be the 0.3% CPU one) ...
              great!

              lokki primitive UI :-)

              primitive? It's text-based, so it's very evolved, to the point where all the pointless frills have been removed.

                  giuliomoro -mfpu=neon-vfpv4 should be -mfpu=neon

                  yep, that was it. it runs with all optimisations now...

                    Great. vfpv4 is for armv8. armv7 has the vfpv3.

                    with all the optimisations in place it looks even better:

                    Every 0.5s: cat /proc/xenomai/sched/stat                                                                                 bela: Tue Dec 17 23:53:27 2019

CPU  PID    MSW        CSW        XSC        PF    STAT       %CPU  NAME
  0  0      0          1061315    0          0     00018000   85.3  [ROOT]
  0  8067   3          4          13         0     000600c0    0.0  jalv
  0  8073   2          3          4          0     000480c0    0.0  bela-midiIn_hw:0,0,0
  0  8077   1          88810      88813      0     00048046   14.4  bela-audio
  0  0      0          405345     0          0     00000000    0.0  [IRQ16: [timer]]
  0  0      0          88819      0          0     00000000    0.2  [IRQ180: rtdm_pruss_irq_irq]

                    great!

                    is there a way to change the PGA gain settings from the command line when running jalv?

                    giuliomoro primitive? It's text-based, so it's very evolved

                    of course.

                        so by tomorrow morning i want that LV2host with all added features :-) and with a nice primitive UI

                          lokki is there a way to change the PGA gain settings from the command line when running jalv?

                          no they are not exposed. An easy way to do change these is to hardcode them within jalv where the settings are set:
                          https://github.com/giuliomoro/jalv/blob/Bela/src/bela.c#L274-L286

                          add

                          settings.pgaGain[0] = 20;

                            lokki so by tomorrow morning i want that LV2host with all added features :-) and with a nice primitive UI

                            @adanlbenito had an automatic nexus-UI (or p5.hjs?) GUI generator for this host, not sure where that is gone ...

                              I have indeed. The most recent commit is from March 2019 while previously it was from December 2018

                                giuliomoro ah, did not realize GitHub actually keeps the date of your local machine, thought it was by upload date, silly me..

                                will see if this changes any of my port problems!