crate rs_ws281x is compiled with undefined instruction

[ziutech]

Checklist

• I've looked through the issues and pull requests for similar reports

Describe your issue

Compiling crate rs_ws281x with cross for target armv7-unknown-linux-gnueabihf results in a illegal instruction.

What target(s) are you cross-compiling for?

armv7-unknown-linux-gnueabihf

Which operating system is the host (e.g computer cross is on) running?

• macOS
• Windows
• Linux / BSD
• other OS (specify in description)

What architecture is the host?

• x86_64 / AMD64
• arm32
• arm64 (including Mac M1)

What container engine is cross using?

• docker
• podman
• other container engine (specify in description)

cross version

cross 0.2.5 (ac4c11c 2024-09-24)

Example

git clone https://github.com/rpi-ws281x/rpi-ws281x-rust

# I had to set correct pin, strip len and strip type in examples/basic.rs, otherwise it did not run

cross b --target armv7-unknown-linux-gnueabihf --example basic

# copy to raspberry pi

./basic

# Illegal instruction

Additional information / notes

(gdb) disas $pc-40,$pc+40
Dump of assembler code from 0x425734 to 0x425784:
   0x00425734 <setup_pwm+1700>: tst     r0, #10
   0x00425738 <setup_pwm+1704>: bl      0x4791d0
   0x0042573c <setup_pwm+1708>: tst     r0, #1
   0x00425740 <setup_pwm+1712>: tst     r0, #0
   0x00425744 <setup_pwm+1716>: str     r0, [sp, #120]  ; 0x78
   0x00425748 <setup_pwm+1720>: b       0x42574c <setup_pwm+1724>
   0x0042574c <setup_pwm+1724>: ldr     r0, [sp, #120]  ; 0x78
   0x00425750 <setup_pwm+1728>: and     r0, r0, #1
   0x00425754 <setup_pwm+1732>: tst     r0, #1
   0x00425758 <setup_pwm+1736>: bne     0x425760 <setup_pwm+1744>
=> 0x0042575c <setup_pwm+1740>: udf     #65006  ; 0xfdee
   0x00425760 <setup_pwm+1744>: tst     r0, #1
   0x00425764 <setup_pwm+1748>: b       0x425768 <setup_pwm+1752>
   0x00425768 <setup_pwm+1752>: tst     r0, #1
   0x0042576c <setup_pwm+1756>: str     r0, [sp, #116]  ; 0x74
   0x00425770 <setup_pwm+1760>: b       0x425774 <setup_pwm+1764>
   0x00425774 <setup_pwm+1764>: ldr     r0, [sp, #116]  ; 0x74
   0x00425778 <setup_pwm+1768>: and     r0, r0, #1
   0x0042577c <setup_pwm+1772>: tst     r0, #1
   0x00425780 <setup_pwm+1776>: bne     0x425788 <setup_pwm+1784>
End of assembler dump.

Potentially related issue: ziglang/zig#16585

[Emilgardis]

Are you sure armv7 is correct? What rpi is this?

[Emilgardis]

That udf looks like a proper udf call, im not sure this is a cross-rs issue

[ziutech]

Are you sure armv7 is correct? What rpi is this?

It's for rpi 3. I'm not sure if armv7 is correct, I used to compile for this target without cross and it worked. Now I need to compile for older glibc, and it's not working anymore.

[Emilgardis]

the thing is, all cross does is give you a cross compiler, it might be an issue with the cc, would want to the opcode of the instruction it's generating that is shown as udf

[ziutech]

Right, to me this looks like an issue with zig. I was not sure if I should report this here, in cargo-zigbuild or in zig. Sorry for that.

I found a way to do what I wanted to do without zig, by using a custom docker image, so this can probably be closed.

[Emilgardis]

oh, are you using zig in Cross.toml?

[ziutech]

oh, are you using zig in Cross.toml?

Yes, I forgot to specify that.