Illegal Instruction during early init on Armv7 (xcompiled from darwin/amd64)

[jdizzle]

Please answer these questions before submitting your issue. Thanks!

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

go version go1.6.3 darwin/amd64

installed via brew

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.6.3/libexec"
GOTOOLDIR="/usr/local/Cellar/go/1.6.3/libexec/pkg/tool/darwin_amd64"
GO15VENDOREXPERIMENT="1"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fno-common"
CXX="clang++"
CGO_ENABLED="1"

However I am cross compiling for a linux arm7 system

GOARM=7
GOARCH=arm
GOOS=linux

What did you do?

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

// Our first program will print the classic "hello world"
// message. Here's the full source code.
package main

import "fmt"

func main() {
    fmt.Println("hello world")
}

What did you see instead?

The executable immediately crashes due to an illegal instruction signal. Here is the output of gdserver:

Program received signal SIGILL, Illegal instruction.
runtime.check () at /usr/local/Cellar/go/1.6.3/libexec/src/runtime/runtime1.go:152
152	/usr/local/Cellar/go/1.6.3/libexec/src/runtime/runtime1.go: No such file or directory.
(gdb) disass
Dump of assembler code for function runtime.check:
   0x00049f8c <+0>:	ldr	r1, [r10, #8]
   0x00049f90 <+4>:	cmp	sp, r1
   0x00049f94 <+8>:	bls	0x4a53c <runtime.check+1456>
   0x00049f98 <+12>:	str	lr, [sp, #-76]!	; 0xffffffb4
   0x00049f9c <+16>:	mov	r0, #0
   0x00049fa0 <+20>:	mov	r0, #0
   0x00049fa4 <+24>:	mov	r0, #0
   0x00049fa8 <+28>:	mov	r0, #0
   0x00049fac <+32>:	mov	r0, #0
   0x00049fb0 <+36>:	str	r0, [sp, #48]	; 0x30
   0x00049fb4 <+40>:	mov	r0, #0
   0x00049fb8 <+44>:	mov	r0, #0
   0x00049fbc <+48>:	mov	r1, #0
   0x00049fc0 <+52>:	mov	r0, #0
   0x00049fc4 <+56>:	mov	r1, #0
=> 0x00049fc8 <+60>:	vmov.f32	s0, #112	; 0x3f800000  1.0
   0x00049fcc <+64>:	vsub.f32	s0, s0, s0
   0x00049fd0 <+68>:	vstr	s0, [sp, #44]	; 0x2c
   0x00049fd4 <+72>:	vmov.f32	s0, #112	; 0x3f800000  1.0
   0x00049fd8 <+76>:	vsub.f32	s0, s0, s0
   0x00049fdc <+80>:	vstr	s0, [sp, #40]	; 0x28
   0x00049fe0 <+84>:	vmov.f64	d0, #112	; 0x3f800000  1.0
   0x00049fe4 <+88>:	vsub.f64	d0, d0, d0
   0x00049fe8 <+92>:	vstr	d0, [sp, #60]	; 0x3c
   0x00049fec <+96>:	vmov.f64	d0, #112	; 0x3f800000  1.0
   0x00049ff0 <+100>:	vsub.f64	d0, d0, d0
   0x00049ff4 <+104>:	vstr	d0, [sp, #52]	; 0x34
   0x00049ff8 <+108>:	mov	r0, #0
   0x00049ffc <+112>:	str	r0, [sp, #72]	; 0x48
   0x0004a000 <+116>:	mov	r0, #0
   0x0004a004 <+120>:	mov	r0, #0
   0x0004a008 <+124>:	mov	r0, #0
   0x0004a00c <+128>:	strb	r0, [sp, #36]	; 0x24
   0x0004a010 <+132>:	strb	r0, [sp, #37]	; 0x25
   0x0004a014 <+136>:	strb	r0, [sp, #38]	; 0x26
---Type <return> to continue, or q <return> to quit---q
Quit

It appears that the vmov.f32 instruction is not supported? I'm using a Cortex A9 chip, and the datasheet for the SoC shows the FPU. Is this possibly a software configuration issue on my end. I have ARM_THUMB=n in my kernel configuration.

[minux]

Probably your SoC only support VFPv1, not VFPv3 as required by GOARM=7. Try rebuilding with GOARM=6 to see if it fixes the problem.

[jdizzle]

I tried with GOARM=6. I get the same signal, but on a different instruction. Thanks for the reply!

Program received signal SIGILL, Illegal instruction.
0x0004a084 in runtime.check () at /usr/local/Cellar/go/1.6.3/libexec/src/runtime/runtime1.go:152
152	/usr/local/Cellar/go/1.6.3/libexec/src/runtime/runtime1.go: No such file or directory.
(gdb) disass
Dump of assembler code for function runtime.check:
   0x0004a044 <+0>:	ldr	r1, [r10, #8]
   0x0004a048 <+4>:	cmp	sp, r1
   0x0004a04c <+8>:	bls	0x4a5f4 <runtime.check+1456>
   0x0004a050 <+12>:	str	lr, [sp, #-76]!	; 0xffffffb4
   0x0004a054 <+16>:	mov	r0, #0
   0x0004a058 <+20>:	mov	r0, #0
   0x0004a05c <+24>:	mov	r0, #0
   0x0004a060 <+28>:	mov	r0, #0
   0x0004a064 <+32>:	mov	r0, #0
   0x0004a068 <+36>:	str	r0, [sp, #48]	; 0x30
   0x0004a06c <+40>:	mov	r0, #0
   0x0004a070 <+44>:	mov	r0, #0
   0x0004a074 <+48>:	mov	r1, #0
   0x0004a078 <+52>:	mov	r0, #0
   0x0004a07c <+56>:	mov	r1, #0
   0x0004a080 <+60>:	ldr	r11, [pc, #1404]	; 0x4a604 <runtime.check+1472>
=> 0x0004a084 <+64>:	vldr	s0, [r11]
   0x0004a088 <+68>:	vstr	s0, [sp, #44]	; 0x2c
   0x0004a08c <+72>:	ldr	r11, [pc, #1392]	; 0x4a604 <runtime.check+1472>
   0x0004a090 <+76>:	vldr	s0, [r11]
   0x0004a094 <+80>:	vstr	s0, [sp, #40]	; 0x28
   0x0004a098 <+84>:	ldr	r11, [pc, #1384]	; 0x4a608 <runtime.check+1476>
   0x0004a09c <+88>:	vldr	d0, [r11]
   0x0004a0a0 <+92>:	vstr	d0, [sp, #60]	; 0x3c
   0x0004a0a4 <+96>:	ldr	r11, [pc, #1372]	; 0x4a608 <runtime.check+1476>
   0x0004a0a8 <+100>:	vldr	d0, [r11]
   0x0004a0ac <+104>:	vstr	d0, [sp, #52]	; 0x34
   0x0004a0b0 <+108>:	mov	r0, #0
   0x0004a0b4 <+112>:	str	r0, [sp, #72]	; 0x48
   0x0004a0b8 <+116>:	mov	r0, #0
   0x0004a0bc <+120>:	mov	r0, #0
   0x0004a0c0 <+124>:	mov	r0, #0
   0x0004a0c4 <+128>:	strb	r0, [sp, #36]	; 0x24
   0x0004a0c8 <+132>:	strb	r0, [sp, #37]	; 0x25
   0x0004a0cc <+136>:	strb	r0, [sp, #38]	; 0x26

[davecheney]

Can you post /proc/cpuinfo for us? Thank.

…

On Sun, 1 Jan 2017, 13:21 jdizzle ***@***.***> wrote: I tried with GOARM=6. I get the same signal, but on a different instruction. Thanks for the reply! Program received signal SIGILL, Illegal instruction. 0x0004a084 in runtime.check () at /usr/local/Cellar/go/1.6.3/libexec/src/runtime/runtime1.go:152 152 /usr/local/Cellar/go/1.6.3/libexec/src/runtime/runtime1.go: No such file or directory. (gdb) disass Dump of assembler code for function runtime.check: 0x0004a044 <+0>: ldr r1, [r10, #8] 0x0004a048 <+4>: cmp sp, r1 0x0004a04c <+8>: bls 0x4a5f4 <runtime.check+1456> 0x0004a050 <+12>: str lr, [sp, #-76]! ; 0xffffffb4 0x0004a054 <+16>: mov r0, #0 0x0004a058 <+20>: mov r0, #0 0x0004a05c <+24>: mov r0, #0 0x0004a060 <+28>: mov r0, #0 0x0004a064 <+32>: mov r0, #0 0x0004a068 <+36>: str r0, [sp, #48] ; 0x30 0x0004a06c <+40>: mov r0, #0 0x0004a070 <+44>: mov r0, #0 0x0004a074 <+48>: mov r1, #0 0x0004a078 <+52>: mov r0, #0 0x0004a07c <+56>: mov r1, #0 0x0004a080 <+60>: ldr r11, [pc, #1404] ; 0x4a604 <runtime.check+1472> => 0x0004a084 <+64>: vldr s0, [r11] 0x0004a088 <+68>: vstr s0, [sp, #44] ; 0x2c 0x0004a08c <+72>: ldr r11, [pc, #1392] ; 0x4a604 <runtime.check+1472> 0x0004a090 <+76>: vldr s0, [r11] 0x0004a094 <+80>: vstr s0, [sp, #40] ; 0x28 0x0004a098 <+84>: ldr r11, [pc, #1384] ; 0x4a608 <runtime.check+1476> 0x0004a09c <+88>: vldr d0, [r11] 0x0004a0a0 <+92>: vstr d0, [sp, #60] ; 0x3c 0x0004a0a4 <+96>: ldr r11, [pc, #1372] ; 0x4a608 <runtime.check+1476> 0x0004a0a8 <+100>: vldr d0, [r11] 0x0004a0ac <+104>: vstr d0, [sp, #52] ; 0x34 0x0004a0b0 <+108>: mov r0, #0 0x0004a0b4 <+112>: str r0, [sp, #72] ; 0x48 0x0004a0b8 <+116>: mov r0, #0 0x0004a0bc <+120>: mov r0, #0 0x0004a0c0 <+124>: mov r0, #0 0x0004a0c4 <+128>: strb r0, [sp, #36] ; 0x24 0x0004a0c8 <+132>: strb r0, [sp, #37] ; 0x25 0x0004a0cc <+136>: strb r0, [sp, #38] ; 0x26 — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#18483 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAcA5I0b72HuKahCbF342Dlj-LADXiCks5rNw2rgaJpZM4LYpnB> .

[jdizzle]

:~$ cat /proc/cpuinfo 
Processor	: ARMv7 Processor rev 0 (v7l)
processor	: 0
BogoMIPS	: 2393.70

processor	: 1
BogoMIPS	: 2393.70

Features	: swp half fastmult edsp tls 
CPU implementer	: 0x41
CPU architecture: 7
CPU variant	: 0x3
CPU part	: 0xc09
CPU revision	: 0

[minux]

looks like either the processor doesn't have VFP at all, or the kernel has disabled VFP support. You will need to use GOARM=5. If it's the first case, do you mind disclose the SoC part number? (Just curious, because I haven't seen any ARMv7 SoC without VFP.)

[davecheney]

Sadly you'll have to compile with GOARM=5 to use soft float emulation.

…

On Sun, 1 Jan 2017, 14:04 Minux Ma ***@***.***> wrote: looks like either the processor doesn't have VFP at all, or the kernel has disabled VFP support. If it's the first case, do you mind disclose the SoC part number? (Just curious, because I haven't seen any ARMv7 SoC without VFP.) — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#18483 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAcA2xXCU0UTjyN2K0QFuZpkPkMZVvpks5rNxewgaJpZM4LYpnB> .

[jdizzle]

I'm using a BCM58625. I checked and found my kernel has VFP=n in the config. I switched it to VFP=y, recompiled, and the go code works!

Thank you very much for your prompt and useful assistance.

[davecheney]

Not a problem, I'm glad you got it working.