Undefined symbols for __sync... when building for ARMv5 Linux targets

[MDr164]

Currently when building for ARMv5 Linux, using flags GOARCH=arm GOARM=5 the TinyGo compiler (0.29.0) returns following error:

tinygo:ld.lld: error: undefined symbol: __sync_val_compare_and_swap_4
>>> referenced by doc.go:166 (/usr/lib/go/src/sync/atomic/doc.go:166)
>>>               /home/user/.cache/tinygo/thinlto/llvmcache-C44B4F4EEE0E036D40F53EC1B801A495DE509B56:((*sync/atomic.Value).Store)
>>> referenced by doc.go:114 (/usr/lib/go/src/sync/atomic/doc.go:114)
>>>               /home/user/.cache/tinygo/thinlto/llvmcache-C44B4F4EEE0E036D40F53EC1B801A495DE509B56:((*sync/atomic.Value).Store)

tinygo:ld.lld: error: undefined symbol: __sync_lock_test_and_set_4
>>> referenced by doc.go:192 (/usr/lib/go/src/sync/atomic/doc.go:192)
>>>               /home/user/.cache/tinygo/thinlto/llvmcache-C44B4F4EEE0E036D40F53EC1B801A495DE509B56:((*sync/atomic.Value).Store)
>>> referenced by value.go:0 (/usr/lib/go/src/sync/atomic/value.go:0)
>>>               /home/user/.cache/tinygo/thinlto/llvmcache-C44B4F4EEE0E036D40F53EC1B801A495DE509B56:((*sync/atomic.Value).Store)
>>> referenced by scheduler_any.go:24 (/usr/lib/tinygo/src/runtime/scheduler_any.go:24)
>>>               /home/user/.cache/tinygo/thinlto/llvmcache-C44B4F4EEE0E036D40F53EC1B801A495DE509B56:(runtime.run$1$gowrapper)
>>> referenced 2 more times
failed to run tool: ld.lld
error: failed to link /tmp/tinygo1270461697/main: exit status 1

This behavior is not being observed for GOARM=6 and GOARM=7

Source code to reproduce:

package main

import "fmt"

func main() {
	fmt.Println("TEST")
}

[laurento]

It seems it is still the case using go v1.21.7 and tinygo v0.30.0

[aykevl]

I looked into it a bit and the usual way these are implemented seems to be by calling into a kernel-provided function. That's somewhat involved, though it could be done.

What's the target where you need GOARM=5? It might help to give a solution.

[laurento]

Before reading this issue, I was using GOARM=5 to target my Raspberry Pi first generation. However, I then realized it is actually an armv6l so I started using GOARM=6 and, as mentioned already, it works just fine.

[MDr164]

The target for me is the Aspeed AST2500 SoC which is armv6k but without FPU. Since Go 1.22 we actually got softfloat for ARM merged so I'm currently building with GOARM=6,softfloat. Actually I'd have to check again with the softfloat variant if it builds. Thanks for reminding me of this issue.

Ah right, 0.30.0 has no 1.22 support...

[deadprogram]

Hello all. Trying to determine if there is some specific things to be done on this issue, or it should be closed since I think this is actually covered by #4177

What does everyone think?

[MDr164]

The PR i put up solves the initial issue I had for me at least as I don't have to target v5 anymore with my v6 and v7 softfloat targets. Not sure if the root cause is fixed but for my usecase I'm fine with closing.

[deadprogram]

Thanks @MDr164