Problems compiling for ARM

[Jørgen Nordmoen]

Hi.

I'm trying to compile OpenBLAS for ARM, specifically for STM32F405, but currently cross-compiling from git doesn't work for me.
I have tried the following command to cross-compile:

make CC=arm-none-eabi-gcc AR=arm-none-eabi-ar HOST=gcc TARGET=ARMV7 USE_THREAD=0

But I get the following error:

/usr/lib/gcc/arm-none-eabi/5.2.0/../../../../arm-none-eabi/lib/libc.a(lib_a-exit.o): In function `exit':
exit.c:(.text.exit+0x2c): undefined reference to `_exit'
/usr/lib/gcc/arm-none-eabi/5.2.0/../../../../arm-none-eabi/lib/libc.a(lib_a-sbrkr.o): In function `_sbrk_r':
sbrkr.c:(.text._sbrk_r+0x18): undefined reference to `_sbrk'
/usr/lib/gcc/arm-none-eabi/5.2.0/../../../../arm-none-eabi/lib/libc.a(lib_a-writer.o): In function `_write_r':
writer.c:(.text._write_r+0x24): undefined reference to `_write'
/usr/lib/gcc/arm-none-eabi/5.2.0/../../../../arm-none-eabi/lib/libc.a(lib_a-closer.o): In function `_close_r':
closer.c:(.text._close_r+0x18): undefined reference to `_close'
/usr/lib/gcc/arm-none-eabi/5.2.0/../../../../arm-none-eabi/lib/libc.a(lib_a-lseekr.o): In function `_lseek_r':
lseekr.c:(.text._lseek_r+0x24): undefined reference to `_lseek'
/usr/lib/gcc/arm-none-eabi/5.2.0/../../../../arm-none-eabi/lib/libc.a(lib_a-readr.o): In function `_read_r':
readr.c:(.text._read_r+0x24): undefined reference to `_read'
/usr/lib/gcc/arm-none-eabi/5.2.0/../../../../arm-none-eabi/lib/libc.a(lib_a-fstatr.o): In function `_fstat_r':
fstatr.c:(.text._fstat_r+0x20): undefined reference to `_fstat'
/usr/lib/gcc/arm-none-eabi/5.2.0/../../../../arm-none-eabi/lib/libc.a(lib_a-isattyr.o): In function `_isatty_r':
isattyr.c:(.text._isatty_r+0x18): undefined reference to `_isatty'
collect2: error: ld returned 1 exit status

I'm trying to use cblas and lapacke from OpenBlas in a program used for Crazyflie 2.0, but when using the precompiled .so for ARMv7 it doesn't work either. I would like to get cross-compiling to work so if anyone has any suggestions on what is wrong with the above command I would appreciate it.

[Zhang Xianyi]

Hi,

I didn't test cross compiling for Cortex-M. I am not sure the assembly codes can run on your MCU.

I suggest you can try OpenBLAS arm C kernels.

1) Edit Makefile.arm,  

ifeq ($(CORE), ARMV5)

CCOMMON_OPT += -marm -march=armv5

FCOMMON_OPT += -marm -march=armv5

endif

You can modify the compiler flags, e.g. -march=armv7e-m

2) Use ARMV5 C kernel target as following.

make TARGET=ARMV5   CC=arm-none-eabi-gcc USE_THREAD=0 HOSTCC=gcc FC=arm-none-eabi-gfortran

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[Jørgen Nordmoen]

Thank you for the prompt reply. Unfortunately I still can't get the code to compile. However, there seems to be several problems that can potentially stop this.

First of all, I edited the `Makefile.arm` so that it contained the following:

ifeq ($(CORE), CORETEXM4F)
CCOMMON_OPT += -marm -mfpu=neon-vfpv4 -mtune=cortex-m4 -mfloat-abi=hard -march=armv7e-m
FCOMMON_OPT += -marm -mfpu=neon-vfpv4 -mtune=cortex-m4 -mfloat-abi=hard -march=armv7e-m
endif

(Note I also added the same options under ARMV5, but I get the same error regardless of using `TARGET=` or `CORE=` )

Then I tried to run the command as following:

make CORE=CORETEXM4F CC=arm-none-eabi-gcc USE_THREAD=0 HOSTCC=gcc AR=arm-none-eabi-ar

which results in the following error:

scal.c:1:0: error: target CPU does not support ARM mode
 /*********************************************************************/
 ^
Makefile:750: recipe for target 'sscal.o' failed
make[1]: *** [sscal.o] Error 1
make[1]: *** Waiting for unfinished jobs....
copy.c:1:0: error: target CPU does not support ARM mode
 /*********************************************************************/
 ^
swap.c:1:0: error: target CPU does not support ARM mode
 /*********************************************************************/
 ^
Makefile:777: recipe for target 'scopy.o' failed
make[1]: *** [scopy.o] Error 1
Makefile:795: recipe for target 'sswap.o' failed
make[1]: *** [sswap.o] Error 1
axpy.c:1:0: error: target CPU does not support ARM mode
 /*********************************************************************/
 ^
Makefile:723: recipe for target 'saxpy.o' failed
make[1]: *** [saxpy.o] Error 1
make[1]: Leaving directory '/home/username/repos/OpenBLAS/interface'
Makefile:143: recipe for target 'libs' failed
make: *** [libs] Error 1

In addition, I can't find a Fortran cross-compiler for ARM, which is why I have not included `FC=` in the command ran above. I'm trying to build on ArchLinux, but I can't find any Fortran cross-compiler and in Ubuntu the only cross-compiler I can find is gnueabi which if I'm not mistaken does not work unless Linux is present.

Any suggestion of what the next step should be?

[Jørgen Nordmoen]

I got a bit further after some more tries.

Changed the `CORE` configuration above to:

ifeq ($(CORE), CORTEXM4F)

CCOMMON_OPT += -marm -mfpu=neon-vfpv4 -mtune=cortex-

m4
FCOMMON_OPT += -marm -mfpu=neon-vfpv4 -mtune=cortex-m4
endif

And execute with:

make CORE=CORTEXM4F CC=arm-none-eabi-gcc HOSTCC=gcc USE_THREAD=0 NO_LAPACK=1

But it still will not compile.

In file included from axpy.c:40:0:
../common.h:112:22: fatal error: sys/mman.h: No such file or directory
compilation terminated.
In file included from copy.c:40:0:
../common.h:112:22: fatal error: sys/mman.h: No such file or directory
compilation terminated.

Makefile:723: recipe for target 'saxpy.o' failed
make[1]: *** [saxpy.o] Error 1

make[1]: *** Waiting for unfinished jobs....

Makefile:777: recipe for target 'scopy.o' failed
make[1]: *** [scopy.o] Error 1

In file included from scal.c:40:0:
../common.h:112:22: fatal error: sys/mman.h: No such file or directory
compilation terminated.

Makefile:750: recipe for target 'sscal.o' failed
make[1]: *** [sscal.o] Error 1

In file included from swap.c:40:0:
../common.h:112:22: fatal error: sys/mman.h: No such file or directory
compilation terminated.

Makefile:795: recipe for target 'sswap.o' failed
make[1]: *** [sswap.o] Error 1

make[1]: Leaving directory '/home/username/repos/OpenBLAS/interface'
Makefile:143: recipe for target 'libs' failed
make: *** [libs] Error 1

Which seems like an error where Arch Linux has moved or I have not install a needed library.

[Zhang Xianyi]

Please don't change CORE.

ifeq ($(CORE), ARMV5)
CCOMMON_OPT += -marm -mfpu=neon-vfpv4 -mtune=cortex-m4 -mfloat-abi=hard -march=armv7e-m
FCOMMON_OPT += -marm -mfpu=neon-vfpv4 -mtune=cortex-m4 -mfloat-abi=hard -march=armv7e-m
endif

make CORE=ARMV5 CC=arm-none-eabi-gcc HOSTCC=gcc USE_THREAD=0 NO_LAPACK=1