fatal error: gnu/stubs-soft.h: No such file or directory

Question

I had the below error while cross compiling a helloworld program on 64 bit Ubuntu 16.04, for 32 bit Cortex A9 platform.

$ make
/usr/local/comp/poky/1.7/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc -march=armv7-a -mthumb-interwork -mtune=cortex-a9 --sysroot=/usr/local/comp/poky/1.7/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi -Iinclude -Wall -O3 -c -o main.o main.c
In file included from /usr/local/comp/poky/1.7/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi/usr/include/features.h:389:0,
             from /usr/local/comp/poky/1.7/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi/usr/include/stdio.h:27,
             from main.c:5:
/usr/local/comp/poky/1.7/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi/usr/include/gnu/stubs.h:7:29: fatal error: gnu/stubs-soft.h: No such file or directory
# include <gnu/stubs-soft.h>
                         ^
compilation terminated.
makefile:45: recipe for target 'main.o' failed
make: *** [main.o] Error 1

Then I examine the content of the stubs.h file:

$ cat /usr/local/comp/poky/1.7/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi/usr/include/gnu/stubs.h 
/* This file is automatically generated.
   This file selects the right generated file of `__stub_FUNCTION' macros
   based on the architecture being compiled for.  */


#if !defined __ARM_PCS_VFP
# include <gnu/stubs-soft.h>
#endif
#if defined __ARM_PCS_VFP
# include <gnu/stubs-hard.h>
#endif

Shall I define the _ARM_PCS_VFP in the makefile?

Answer 1

From the name of your cross compiler, "cortexa9hf-vfp-neon-poky-linux-gnueabi", it targets the Cortex-A9 with VFP architecture and neon enabled. Adding -mfloat-abi=hard switch should solve the problem.

From GCC manual:

-mfloat-abi=name:

Specifies which floating-point ABI to use. Permissible values are: ‘soft’, ‘softfp’ and ‘hard’.

Specifying ‘soft’ causes GCC to generate output containing library calls for floating-point operations. ‘softfp’ allows the generation of code using hardware floating-point instructions, but still uses the soft-float calling conventions. ‘hard’ allows generation of floating-point instructions and uses FPU-specific calling conventions.

The default depends on the specific target configuration. Note that the hard-float and soft-float ABIs are not link-compatible; you must compile your entire program with the same ABI, and link with a compatible set of libraries.