I need to cross compile c++ code for an embedded device with the specs shown below with hardware float operations support. Cross compiling from Ubuntu 20.04 without hardware float support is easy, i can just run arm-linux-gnueabi-g++ -marm -mcpu=arm926ej-s -mfloat-abi=soft -mfpu=vfp and it will work. When running with -mfloat-abi=hard I get:

/usr/lib/gcc-cross/arm-linux-gnueabi/9/../../../../arm-linux-gnueabi/bin/ld: error: ArmSimulateStartStop uses VFP register arguments, /usr/lib/gcc-cross/arm-linux-gnueabi/9/crtbegin.o does not
/usr/lib/gcc-cross/arm-linux-gnueabi/9/../../../../arm-linux-gnueabi/bin/ld: failed to merge target specific data of file /usr/lib/gcc-cross/arm-linux-gnueabi/9/crtbegin.o
/usr/lib/gcc-cross/arm-linux-gnueabi/9/../../../../arm-linux-gnueabi/bin/ld: error: ArmSimulateStartStop uses VFP register arguments, /usr/lib/gcc-cross/arm-linux-gnueabi/9/crtend.o does not
/usr/lib/gcc-cross/arm-linux-gnueabi/9/../../../../arm-linux-gnueabi/bin/ld: failed to merge target specific data of file /usr/lib/gcc-cross/arm-linux-gnueabi/9/crtend.o
collect2: error: ld returned 1 exit status
make: *** [Makefile:12: CrossCompile] Error 1

I know this processor supports hardware float support, it says in the arm documentation. I downloaded buildroot and crosstool but I don't know how to configure them right for my device hardware. How can I cross compile with VFP support?

Device specs:

~ $ cat /proc/cpuinfo 
Processor       : ARM926EJ-S rev 5 (v5l) 
BogoMIPS        : 197.83 
Features        : swp half thumb fastmult edsp java 
CPU implementer : 0x41 
CPU architecture: 5TEJ 
CPU variant     : 0x0 
CPU part        : 0x926 
CPU revision    : 5

~ $ cat /proc/version 
Linux version 2.6.36 (owzafs@PCOWZAFS) (gcc version 4.4.1 (Sourcery G++ Lite 2010q1-202) ) #464 PREEMPT Thu Apr 19 13:50:56 CEST 2018 

Question on SE: https://unix.stackexchange.com/questions/592905/crosscompiling-for-arm926ej-s-device-with-hardware-float-operations-support

Could it be related to your target triple? I see you have arm-linux-gnueabi, but I think there’s another version specifically for hardware floating point: arm-linux-gnueabihf. I’m not experience with Ubuntu, but my search did turn up a g++ package that looks promising.

https://packages.ubuntu.com/search?keywords=g%2B%2B-arm-linux-gnueabihf

Cheers,

g+-arm-linux-gnueabihf is for armv7 and up. See here and here. The one in the question is armv5(tej).

Looks like the objects crtbegin.o and crtend.o doens not match with the main line build. I feel that the best method is to recompile crtbegin.s and crtend.s need to be recompiled with the same setting -mfloat-abi=hard, create the seperate crtbegin.o and crtend.o and retry.

BV Ramesh.

I've got the following V5TE-related files:

~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/hard/crtn.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/hard/crtfastmath.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/hard/crtend.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/hard/crti.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/hard/crtbegin.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/softfp/crtn.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/softfp/crtfastmath.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/softfp/crtend.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/softfp/crti.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/lib/gcc/arm-none-eabi/9.3.1/arm/v5te/softfp/crtbegin.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/arm-none-eabi/lib/arm/v5te/hard/crt0.o
~/bin/gcc-arm-none-eabi-9-2020-q2-update/arm-none-eabi/lib/arm/v5te/softfp/crt0.o

EDIT: The following command worked for me:

arm-none-eabi-gcc -marm -mcpu=arm926ej-s -mfloat-abi=hard -mfpu=vfp -lc -specs=nosys.specs -Wl,-Map=arm926ej.map arm926ej.c

Hope this helps.