cmd/compile: mips: running error SIGILL: illegal instruction

[shownb]

What version of Go are you using (go version)?

$ go version
go version go1.12 linux/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

$ go env
build on : amd64 linux,
runing on:mips16 Linux version 2.6.30.9

What did you do?

file

package main
import (
	"fmt"
)
func main() {
	fmt.Printf("see me you win")
}

build command:
i have tried
GOOS=linux GOARCH=mips GOMIPS=softfloat go build -a test.go
GOOS=linux GOARCH=mipsle GOMIPS=softfloat go build -a test.go

i run in the target:
mips output like

Illegal instruction

mipsle output like that

./test: line 1: syntax error: "(" unexpected

it seems like that the softfloat don't work.
but i tested the ./test in other openwrt router(closed fpu) it works.

What did you expect to see?

i expect i can see "see me you win" in the target router.

What did you see instead?

Illegal instruction

[cherrymui]

runing on:mips16 Linux version 2.6.30.9

Does your machine support MIPS32R1 instruction set? We don't generate mips16 instructions.

Is your machine big-endian or little-endian? What is uname -a output? /proc/cpuinfo would be also helpful.

[shownb]

runing on:mips16 Linux version 2.6.30.9

Does your machine support MIPS32R1 instruction set? We don't generate mips16 instructions.

Is your machine big-endian or little-endian? What is uname -a output? /proc/cpuinfo would be also helpful.

i think i find the reason.
uname -a like that:

Linux version 2.6.30.9 (vic@sw3-hudson-server) (gcc version 4.4.6 (Realtek RSDK-1.5.6p2) ) #1 Tue Apr 26 09:13:29 CST 2016
/proc/cpuinfo like that:

system type             : RTL9600_MSTC
processor               : 0
cpu model               : 56322
BogoMIPS                : 499.71
tlb_entries             : 64
mips16 implemented      : yes

the rtl seems like that not the really mips

and you don't generate mips16 instructions.what's your suggestion?

[katiehockman]

It sounds like this isn't a bug, just a configuration problem, but please correct me if I'm wrong. For questions about Go, see https://golang.org/wiki/Questions.

I'll leave this issue open for now, but this may be closed later if everything is Working As Intended.

[shownb]

I can build a elf from a cross compile toolchain for the target linux.
The cross comiler is from Realtek (RSDK Release 1.5 . It is the software
development kit for Realtek's in-house processor cores.)
The elf info is like that:
ELF 32-bit MSB executable, MIPS, MIPS-I version 1 (SYSV), statically linked, stripped

I think @cherrymui may be right. may be the target's CPU is not really the mips.

[cherrymui]

ELF 32-bit MSB executable, MIPS, MIPS-I version 1 (SYSV), statically linked, stripped

This looks like that the system is actually MIPS, big-endian. But MIPS-I is too old. It doesn't support newer instructions that we generate (not only floating point so softfloat doesn't help).

Maybe you could try gccgo.

[draganmladjenovic]

@shownb This might be one of those Lexra cores that should be almost full mips32 sans [L|S]WL/[L|S]WR support. Can you tray https://godbolt.org/z/VQLGir on your device to see if it crashes the same way?