Node fails to start on MTK7620: "Illegal instruction"

[Nicholasny]

I cross compiled nodejs for a MIPSel target (without FPU but FPU emulation in the kernel) using the OpenWRT 15.05 Chaos Calmer toolchain. The target CPU is an MT7620A

I compile using:
./configure --without-snapshot --dest-cpu=mipsel --dest-os=linux --without-npm --without-ssl --without-etw --without-perfctr --with-mips-float-abi=soft

However then I run into the problem is describing.
"Illegal instruction"
on any of the js files in the test directory.
I can execute node -v, but not node test.js, or node debug test.js

information see below:

root@OpenWrt:/# cat /proc/cpuinfo
system type     : MediaTek MT7620A ver:2 eco:3
machine         : Ralink MT7620a + MT7610e evaluation board
processor       : 0
cpu model       : MIPS 24KEc V5.0
BogoMIPS        : 385.84
wait instruction    : yes
microsecond timers  : yes
tlb_entries     : 32
extra interrupt vector  : yes
hardware watchpoint : yes, count: 4, address/irw mask: [0x0ffc, 0x0ffc, 0x0ffb, 0x0ffb]
isa         : mips1 mips2 mips32r1 mips32r2
ASEs implemented    : mips16 dsp
shadow register sets    : 1
kscratch registers  : 0
package         : 0
core            : 0
VCED exceptions     : not available
VCEI exceptions     : not available

root@OpenWrt:/# cat /proc/version
Linux version 3.18.23 (root@169da0c77da5) (gcc version 4.8.3 (OpenWrt/Linaro GCC 4.8-2014.04 r47992) ) #47 Thu Jan 21 00:54:13 UTC 2016

root@OpenWrt:/# node -v
v0.12.7

root@OpenWrt:/# which  node
/usr/bin/node

root@OpenWrt:/# node -v
v0.12.7

root@OpenWrt:/# ldd /usr/bin/node
    libz.so.1 => /usr/lib/libz.so.1 (0x77881000)
    libssl.so.1.0.0 => /usr/lib/libssl.so.1.0.0 (0x77823000)
    libcrypto.so.1.0.0 => /usr/lib/libcrypto.so.1.0.0 (0x776be000)
    librt.so.0 => /lib/librt.so.0 (0x776aa000)
    libdl.so.0 => /lib/libdl.so.0 (0x77696000)
    libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x775ae000)
    libm.so.0 => /lib/libm.so.0 (0x77588000)
    libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x77564000)
    libpthread.so.0 => /lib/libpthread.so.0 (0x7753e000)
    libc.so.0 => /lib/libc.so.0 (0x774d2000)
    ld-uClibc.so.0 => /lib/ld-uClibc.so.0 (0x778a4000)

[bnoordhuis]

Can you run gdb --args node test.js -> run -> disassemble $pc,$pc+32 (after the SIGILL)?

[bnoordhuis]

Aside, it's odd that you ran configure with --without-ssl but the binary is linked against libcrypto and libssl.

[Nicholasny]

root@OpenWrt:/# cat test.js
console.log("hello");

root@OpenWrt:~# gdb --args node test.js
GNU gdb (GDB) 7.8
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "mipsel-openwrt-linux".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
http://www.gnu.org/software/gdb/bugs/.
Find the GDB manual and other documentation resources online at:
http://www.gnu.org/software/gdb/documentation/.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from node...done.
(gdb) run
Starting program: /usr/bin/node test.js
warning: Unable to find dynamic linker breakpoint function.
GDB will be unable to debug shared library initializers
and track explicitly loaded dynamic code.
warning: File "/lib/libthread_db-0.9.33.2.so" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
To enable execution of this file add
add-auto-load-safe-path /lib/libthread_db-0.9.33.2.so
line to your configuration file "/root/.gdbinit".
To completely disable this security protection add
set auto-load safe-path /
line to your configuration file "/root/.gdbinit".
For more information about this security protection see the
"Auto-loading safe path" section in the GDB manual. E.g., run from the shell:
info "(gdb)Auto-loading safe path"
warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.

Program received signal SIGILL, Illegal instruction.
0x00c79008 in v8::base::CPU::CPU() ()
(gdb) disassemble $pc,$pc+32
Dump of assembler code from 0xc79008 to 0xc79028:
=> 0x00c79008 <_ZN2v84base3CPUC2Ev+308>: ldc1 $f0,32(s8)
0x00c7900c <_ZN2v84base3CPUC2Ev+312>: mtc1 t0,$f1
0x00c79010 <_ZN2v84base3CPUC2Ev+316>: sdc1 $f0,32(s8)
0x00c79014 <_ZN2v84base3CPUC2Ev+320>: lui v0,0xc8
0x00c79018 <_ZN2v84base3CPUC2Ev+324>: lw a0,32(s8)
0x00c7901c <_ZN2v84base3CPUC2Ev+328>: lw a1,36(s8)
0x00c79020 <_ZN2v84base3CPUC2Ev+332>: lw a2,21216(v0)
0x00c79024 <_ZN2v84base3CPUC2Ev+336>: jal 0xe25c30 __nedf2@plt
End of assembler dump.

[Nicholasny]

root@OpenWrt:/usr/bin# ldd node
libdl.so.0 => /lib/libdl.so.0 (0x7702c000)
librt.so.0 => /lib/librt.so.0 (0x77018000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x76f30000)
libm.so.0 => /lib/libm.so.0 (0x76f0a000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x76ee6000)
libpthread.so.0 => /lib/libpthread.so.0 (0x76ec0000)
libc.so.0 => /lib/libc.so.0 (0x76e54000)
ld-uClibc.so.0 => /lib/ld-uClibc.so.0 (0x77040000)

root@OpenWrt:/usr/bin# node -v
v4.1.2

[mscdex]

Are you sure the kernel has FPU emulation compiled in? Does dmesg | grep -i fpu show anything? I believe it should show something like "Algorithmics/MIPS FPU Emulator" if FPU emulation is in fact enabled in the kernel.

[Nicholasny]

dmesg | grep -i fpu
no any output!
How to enable soft fpu in Openwrt 15.05?
I have select software floating piont in Openwrt, see below:
Advanced configuration options (for developers)->Target Options->[*] Use software floating point by default

[mscdex]

After make menuconfig, you should be able to do make kernel_menuconfig and select the Enable FPU emulation option as shown here.

[Nicholasny]

thanks a lot!!!!! but dmesg | grep -i fpu still no any output!!

[tpham3783]

I am sorry, does the app still crash after enabling software fpu?

[enzomich]

From what I understand, floating point emulation on MIPS platforms was disabled several years ago: https://lists.openwrt.org/pipermail/openwrt-devel/2009-June/004562.html , So, node.js should be compiled with floating point emulation support - but, apparently, it is not. I have this same issue with CC 15.05.1 on a TP-LINK TL-WR1043ND v3 (CPU MIPS 74Kc V5.0): the binary package for Node downloaded from https://downloads.openwrt.org/chaos_calmer/15.05.1/ar71xx/generic/packages/packages/node_v0.12.7-1_ar71xx.ipk crashes on a FP instruction (swc1):

Program received signal SIGILL, Illegal instruction.
0x57e2cc10 in ?? ()
(gdb) disassemble $pc,$pc+32
Dump of assembler code from 0x57e2cc10 to 0x57e2cc30:
=> 0x57e2cc10: swc1 $f30,44(sp)
0x57e2cc14: swc1 $f31,40(sp)
0x57e2cc18: swc1 $f28,36(sp)
0x57e2cc1c: swc1 $f29,32(sp)
0x57e2cc20: swc1 $f26,28(sp)
0x57e2cc24: swc1 $f27,24(sp)
0x57e2cc28: swc1 $f24,20(sp)
0x57e2cc2c: swc1 $f25,16(sp)
End of assembler dump.