cross-compile error: undefined reference to `__atomic_load_8'

Bug report

Bug description:

Should not configure script check if -latomic is needed?

getting build error when cross-compile:

arm-linux-gnueabi-gcc -L/opt/zlib-arm-linux-gnueabi/lib -L/opt/xz-arm-linux-gnueabi/lib -L/opt/readline-arm-linux-gnueabi/lib -L/opt/libffi-arm-linux-gnueabi/lib -L/opt/libtirpc-arm-linux-gnueabi/lib -L/opt/libuuid-arm-linux-gnueabi/lib -L/opt/zlib-arm-linux-gnueabi/lib -L/opt/xz-arm-linux-gnueabi/lib -L/opt/readline-arm-linux-gnueabi/lib -L/opt/libffi-arm-linux-gnueabi/lib -L/opt/libtirpc-arm-linux-gnueabi/lib -L/opt/libuuid-arm-linux-gnueabi/lib   -Xlinker -export-dynamic -o Programs/_testembed Programs/_testembed.o -L. -lpython3.13 -lpthread -ldl  -lpthread -lutil                          -lm 
/root/x-tools/arm-linux-gnueabi/lib/gcc/arm-linux-gnueabi/13.2.0/../../../../arm-linux-gnueabi/bin/ld: ./libpython3.13.so: undefined reference to `__atomic_load_8'
/root/x-tools/arm-linux-gnueabi/lib/gcc/arm-linux-gnueabi/13.2.0/../../../../arm-linux-gnueabi/bin/ld: ./libpython3.13.so: undefined reference to `__atomic_store_8'
/root/x-tools/arm-linux-gnueabi/lib/gcc/arm-linux-gnueabi/13.2.0/../../../../arm-linux-gnueabi/bin/ld: ./libpython3.13.so: undefined reference to `__atomic_fetch_add_8'
/root/x-tools/arm-linux-gnueabi/lib/gcc/arm-linux-gnueabi/13.2.0/../../../../arm-linux-gnueabi/bin/ld: ./libpython3.13.so: undefined reference to `__atomic_compare_exchange_8'
collect2: error: ld returned 1 exit status

configure cmd line:

./configure --prefix=/opt/python-arm-linux-gnueabi-3.13.0 --host=arm-linux-gnueabi --target=arm-linux-gnueabi --build=x86_64-linux-gnu --disable-ipv6 ac_cv_file__dev_ptmx=no ac_cv_file__dev_ptc=no  --enable-shared --with-openssl=/opt/openssl-arm-linux-gnueabi --with-build-python=/root/.pyenv/versions/3.13.0/bin/python

workaround

export LDFLAGS="-latomic $LDFLAGS"

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

The configure script has a check for -latomic. I'm not sure why it's not working on your system:

cpython/configure.ac

Lines 7498 to 7545 in 01fc3b3

    
           AC_CACHE_CHECK([whether libatomic is needed by <pyatomic.h>], 
        
                          [ac_cv_libatomic_needed], 
        
           [AC_RUN_IFELSE([AC_LANG_SOURCE([[ 
        
           // pyatomic.h needs uint64_t and Py_ssize_t types 
        
           #include <stdint.h>  // int64_t, intptr_t 
        
           #ifdef HAVE_SYS_TYPES_H 
        
           #  include <sys/types.h> // ssize_t 
        
           #endif 
        
           // Code adapted from Include/pyport.h 
        
           #if HAVE_SSIZE_T 
        
           typedef ssize_t Py_ssize_t; 
        
           #elif SIZEOF_VOID_P == SIZEOF_SIZE_T 
        
           typedef intptr_t Py_ssize_t; 
        
           #else 
        
           #  error "unable to define Py_ssize_t" 
        
           #endif 
        
           #include "pyatomic.h" 
        
           int main() 
        
           { 
        
               uint64_t value; 
        
               _Py_atomic_store_uint64(&value, 2); 
        
               if (_Py_atomic_or_uint64(&value, 8) != 2) { 
        
                   return 1; // error 
        
               } 
        
               if (_Py_atomic_load_uint64(&value) != 10) { 
        
                   return 1; // error 
        
               } 
        
               uint8_t byte = 0xb8; 
        
               if (_Py_atomic_or_uint8(&byte, 0x2d) != 0xb8) { 
        
                   return 1; // error 
        
               } 
        
               if (_Py_atomic_load_uint8(&byte) != 0xbd) { 
        
                   return 1; // error 
        
               } 
        
               return 0; // all good 
        
           } 
        
           ]])], 
        
             [ac_cv_libatomic_needed=no],  dnl build succeeded 
        
             [ac_cv_libatomic_needed=yes], dnl build failed 
        
             [ac_cv_libatomic_needed=no])  dnl cross compilation 
        
           ]) 
        
           AS_VAR_IF([ac_cv_libatomic_needed], [yes], 
        
                     [LIBS="${LIBS} -latomic" 
        
                      LIBATOMIC=${LIBATOMIC-"-latomic"}]) 
        
           _RESTORE_VAR([CPPFLAGS])

@vstinner

Oh, I guess we disabled it for cross compilation (#109211). cc @vstinner @erlend-aasland

Could we use AC_LINK_IFELSE instead of AC_RUN_IFELSE for this check?

@erlend-aasland

Could we use AC_LINK_IFELSE instead of AC_RUN_IFELSE for this check?

I don't know, it's beyond my autotools skills :-) Maybe @erlend-aasland or @corona10 knows.

I don't know autotools. When Python is cross-compiled, does AC_RUN_IFELSE build the program? Or does it do nothing?

IIRC, the LINK variant only runs the linker, so it should work on a correctly setup cross-compiling environment. The RUN variant also runs the resulting executable, which will fail in a cross-compiling dev environment.

Ah, the check in our configure script defaults to not requiring libatomic if we are cross compiling. Perhaps we want to change that configure branch.

Ah, the check in our configure script defaults to not requiring libatomic if we are cross compiling. Perhaps we want to change that configure branch.

Looking at the past PRs:

Sep 8, 2023: gh-109054: configure checks if libatomic is needed #109101 added the check and made -latomic the default when cross-compiling
Sep 10, 2023: gh-109054: Don't use libatomic on cross-compilation #109211 changed the cross-compling default to not require -latomic to fix wasm32, which is cross-compiled but doesn't support -latomic.

IIRC, the LINK variant only runs the linker, so it should work on a correctly setup cross-compiling environment

I think the link time check should be sufficient for both cross-compiling and native compilation (famous last words). I'll give it a go.

pythongh-125269: Use `AC_LINK_IF_ELSE` to detect if `-latomic` is needed

I think the link time check should be sufficient for both cross-compiling and native compilation (famous last words). I'll give it a go.

Yes, that aligns with my assumptions as well. Let's try.

gh-125269: Use `AC_LINK_IF_ELSE` to detect if `-latomic` is needed (#…

pythongh-125269: Use `AC_LINK_IF_ELSE` to detect if `-latomic` is nee…

[3.13] gh-125269: Use `AC_LINK_IF_ELSE` to detect if `-latomic` is ne…

This should be fixed now in the main and 3.13 branches.

Navigation Menu

Repository navigation

cross-compile error: undefined reference to `__atomic_load_8' #125269

Bug report

Bug description:

workaround

CPython versions tested on:

Operating systems tested on:

Linked PRs

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

	AC_CACHE_CHECK([whether libatomic is needed by <pyatomic.h>],
	[ac_cv_libatomic_needed],
	[AC_RUN_IFELSE([AC_LANG_SOURCE([[
	// pyatomic.h needs uint64_t and Py_ssize_t types
	#include <stdint.h> // int64_t, intptr_t
	#ifdef HAVE_SYS_TYPES_H
	# include <sys/types.h> // ssize_t
	#endif
	// Code adapted from Include/pyport.h
	#if HAVE_SSIZE_T
	typedef ssize_t Py_ssize_t;
	#elif SIZEOF_VOID_P == SIZEOF_SIZE_T
	typedef intptr_t Py_ssize_t;
	#else
	# error "unable to define Py_ssize_t"
	#endif

	#include "pyatomic.h"

	int main()
	{
	uint64_t value;
	_Py_atomic_store_uint64(&value, 2);
	if (_Py_atomic_or_uint64(&value, 8) != 2) {
	return 1; // error
	}
	if (_Py_atomic_load_uint64(&value) != 10) {
	return 1; // error
	}
	uint8_t byte = 0xb8;
	if (_Py_atomic_or_uint8(&byte, 0x2d) != 0xb8) {
	return 1; // error
	}
	if (_Py_atomic_load_uint8(&byte) != 0xbd) {
	return 1; // error
	}
	return 0; // all good
	}
	]])],
	[ac_cv_libatomic_needed=no], dnl build succeeded
	[ac_cv_libatomic_needed=yes], dnl build failed
	[ac_cv_libatomic_needed=no]) dnl cross compilation
	])

	AS_VAR_IF([ac_cv_libatomic_needed], [yes],
	[LIBS="${LIBS} -latomic"
	LIBATOMIC=${LIBATOMIC-"-latomic"}])
	_RESTORE_VAR([CPPFLAGS])

cross-compile error: undefined reference to `__atomic_load_8' #125269

Description

Bug report

Bug description:

workaround

CPython versions tested on:

Operating systems tested on:

Linked PRs

Activity

colesbury commented on Oct 10, 2024

colesbury commented on Oct 10, 2024

colesbury commented on Oct 10, 2024

vstinner commented on Oct 11, 2024

vstinner commented on Oct 11, 2024

erlend-aasland commented on Oct 11, 2024

erlend-aasland commented on Oct 11, 2024

colesbury commented on Oct 13, 2024

erlend-aasland commented on Oct 14, 2024

colesbury commented on Nov 4, 2024

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions