Floating point emulation support for RT-AC88U

[Anson]

Hi,

I am getting "Illegal Instruction" for some go executable and google suggested it may related to no FPU or FPU emulation is not enabled in kernel.

FastFPE math emulation (EXPERIMENTAL) looks enabled by default, I am not sure why it's not working. So I am trying to re-compile kernal with "NWFPE math emulation" or VPF-format floating points maths support. Unfortunately kernel compile failed with below error. Any idea?


~/asuswrt-merlin/release/src-rt-7.14.114.x/src/$ make kernel
:
:
:


make[2]: Entering directory '/home/thx/asuswrt-merlin/release/src/router/compressed'
arm-brcm-linux-uclibcgnueabi-objcopy -O binary -R .note -R .note.gnu.build-id -R .comment -S /home/thx/asuswrt-merlin/release/src-rt-7.14.114.x/src/linux/linux-2.6/vmlinux piggy
/home/thx/asuswrt-merlin/release/src-rt-7.14.114.x/src/ctools/lzma_4k e piggy piggz
arm-brcm-linux-uclibcgnueabi-ld -no-warn-mismatch -T piggy.lds -r -o piggy.o -b binary piggz -b elf32-littlearm
arm-brcm-linux-uclibcgnueabi-ld -static --gc-sections -no-warn-mismatch -T vmlinux.lds -o vmlinux bootarm.o aisdram_ca9.o siutils.o hndarm_ca9.o pcieinit_ca9.o sbutils.o aiutils.o nicpci.o pcie_core.o load.o hndchipc.o hndpmu.o min_osl.o bcmutils.o bcmstdlib.o sromstubs.o nvramstubs.o -L /home/thx/asuswrt-merlin/release/src-rt-6.x.4708/toolchains/hndtools-arm-linux-2.6.36-uclibc-4.5.3/bin/../lib/gcc/arm-brcm-linux-uclibcgnueabi/4.5.3 -lgcc piggy.o
hndpmu.o: In function `si_pmu_chipcontrol':
/home/thx/asuswrt-merlin/release/src-rt-7.14.114.x/src/shared/hndpmu.c:150: undefined reference to `si_pmu_corereg'

Thank you.

 

[Vexira]

im qurios what is the purpose of Floating point emulation support, and what are you trying to achieve by enabling it?

 

[Anson]

im qurios what is the purpose of Floating point emulation support, and what are you trying to achieve by enabling it?

Well, at lease I can get nodeJS running ...

admin@RT-AC88U-B718:/tmp/home/root# node
Illegal instruction

 

[Vexira]

Well, at lease I can get nodeJS running ...

admin@RT-AC88U-B718:/tmp/home/root# node
Illegal instruction

I mean I was asking how does it affect the router if you can get it working?

 

[Anson]

I mean I was asking how does it affect the router if you can get it working?

I was thinking that can fix "Illegal instruction" problem. Or am I looking at a wrong direction?

 

[sfx2000]

Look at Entware - if I recall, they have NodeJS in their tree...

Alt approach would be a Pi2/Pi3 - nodejs is fully supported there, and more RAM available to boot - NodeJS can be very resource intense depending on the code running...

 

[Anson]

Look at Entware - if I recall, they have NodeJS in their tree...

Alt approach would be a Pi2/Pi3 - nodejs is fully supported there, and more RAM available to boot - NodeJS can be very resource intense depending on the code running...

Thanks, I am using the node come with Entware, but not sure why I am getting Illegal instruction, if it's not related to FPU emulation.

 

[ResumeNothing]

Thanks, I am using the node come with Entware, but not sure why I am getting Illegal instruction, if it's not related to FPU emulation.

I'm getting the same error on RT-AC68P. I think you're correct about it being because there's no FPU emulation:

https://github.com/nodejs/node/issues/7343

Depending on your needs, you might be able to get by by install the node_legacy package instead. I was able to get node to work on my router with that.

 

[sfx2000]

when getting into NPM - a lot of the packages are armhf - thanks to the Pi community...

The RT-AC series with Cortex-A9 - they're armel...

gcc options - look at ARMv7-a, -mfloat-abi=soft which should work ok... might try softfp perhaps...

 

[Anson]

when getting into NPM - a lot of the packages are armhf - thanks to the Pi community...

The RT-AC series with Cortex-A9 - they're armel...

gcc options - look at ARMv7-a, -mfloat-abi=soft which should work ok... might try softfp perhaps...

Thanks, bt isn't Cortex-A9 has a FPU ? Or it's removed on art-AC series?

 

[sfx2000]

Thanks, bt isn't Cortex-A9 has a FPU ? Or it's removed on art-AC series?

Cortex-A9 - it's optional... and the Broadcom SoC has not implemented it.

 

[Vexira]

Don't know if this will help you.
https://github.com/nxhack/openwrt-node-packages/issues/15
http://www.linksysinfo.org/index.php?threads/using-fpu-emulator.69940/