undefined reference to `raise' with musl static toolchain

undefined reference to `raise' with musl static toolchain

[Thomas Petazzoni]

Hello,

When building an ARM Cortex-A8 toolchain with Buildroot, using the musl
C library, and its --disable-shared option (to build a static only
toolchain), building some simple programs fail:

thomas@windsurf:~/projets/buildroot (master)$ cat foo.c 
int main(void) { mktime(); return 0; }
$ ./output/host/bin/arm-linux-gcc -o foo foo.c
foo.c: In function ‘main’:
foo.c:1:18: warning: implicit declaration of function ‘mktime’ [-Wimplicit-function-declaration]
 int main(void) { mktime(); return 0; }
                  ^~~~~~
/home/thomas/projets/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/libgcc.a(_dvmd_lnx.o): In function `__aeabi_idiv0':
/home/thomas/projets/buildroot/output/build/host-gcc-final-6.4.0/build/arm-buildroot-linux-musleabihf/libgcc/../../../libgcc/config/arm/lib1funcs.S:1354: undefined reference to `raise'
collect2: error: ld returned 1 exit status

Does that ring any bell ?

It can be reproduced using the following Buildroot defconfig:

BR2_arm=y
BR2_cortex_a8=y
BR2_STATIC_LIBS=y
BR2_TOOLCHAIN_BUILDROOT_MUSL=y
BR2_TOOLCHAIN_BUILDROOT_CXX=y
BR2_INIT_NONE=y
BR2_SYSTEM_BIN_SH_NONE=y
# BR2_TARGET_ROOTFS_TAR is not set

And then using the cross-compiler to build that simple program calling
mktime().

Any idea ?

Note: this is reported in the Buildroot bug tracker as
https://bugs.busybox.net/show_bug.cgi?id=10996.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

Re: undefined reference to `raise' with musl static toolchain

[Alexander Monakov]

On Tue, 8 May 2018, Thomas Petazzoni wrote:
> $ ./output/host/bin/arm-linux-gcc -o foo foo.c

Please add '-v' to the command line and post the resulting log.

Alexander

Re: undefined reference to `raise' with musl static toolchain

[Markus Wichmann]

On Tue, May 08, 2018 at 02:44:17PM +0200, Thomas Petazzoni wrote:
> /home/thomas/projets/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/libgcc.a(_dvmd_lnx.o): In function `__aeabi_idiv0':
> /home/thomas/projets/buildroot/output/build/host-gcc-final-6.4.0/build/arm-buildroot-linux-musleabihf/libgcc/../../../libgcc/config/arm/lib1funcs.S:1354: undefined reference to `raise'
[...]
> 
> Does that ring any bell ?
> 

It would appear that your version of libgcc references libc. Now, with
static linking, the libraries must appear in the correct order to
satisfy all dependencies, but here you have a circular dependency between
libgcc and libc. Since all gcc compiled code depends on libgcc, and libc
is compiled with gcc, there are only two ways to break the cycle:

1. Remove the dependency. No idea how, not unless you basically inline
raise() into __aeabi_idiv0().

2. Add libc again after the command line.

I suspect, once spec files have been taken care of, that the linker
command line will be something like

ld -o a.out crt1.o crtbegin.o crti.o $YOUR_PRJ_OFILES crtend.o crtn.o -lc -lgcc

That would need another "-lc" at the end. Patching the specfile should
do it.

Things like this somewhat highlight the uselessness of collect2, don't
you think? I thought fixing things like this is entirely within its
remit, but no, apparently not.

Another distinct possibility is that your gcc is somehow broken, either
through your action or maybe that version isn't good, but I tend to try
and fix the simple problem first. And patching the spec file is simpler
than debugging gcc.

Ciao,
Markus

Re: undefined reference to `raise' with musl static toolchain

[Rich Felker]

On Tue, May 08, 2018 at 06:22:27PM +0200, Markus Wichmann wrote:
> On Tue, May 08, 2018 at 02:44:17PM +0200, Thomas Petazzoni wrote:
> > /home/thomas/projets/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/libgcc.a(_dvmd_lnx.o): In function `__aeabi_idiv0':
> > /home/thomas/projets/buildroot/output/build/host-gcc-final-6.4.0/build/arm-buildroot-linux-musleabihf/libgcc/../../../libgcc/config/arm/lib1funcs.S:1354: undefined reference to `raise'
> [...]
> > 
> > Does that ring any bell ?
> > 
> 
> It would appear that your version of libgcc references libc. Now, with
> static linking, the libraries must appear in the correct order to
> satisfy all dependencies, but here you have a circular dependency between
> libgcc and libc. Since all gcc compiled code depends on libgcc, and libc
> is compiled with gcc, there are only two ways to break the cycle:
> 
> 1. Remove the dependency. No idea how, not unless you basically inline
> raise() into __aeabi_idiv0().
> 
> 2. Add libc again after the command line.

gcc already does this if you pass -static. I suspect the issue is that
Thomas is using a toolchain where gcc doesn't know it's
static-linking, and ld only static-links because there's no libc.so
present. This setup is highly fragile and afaik it's not intended by
the gcc developers to work. I don't know if there's anything like
--enable-default-static for gcc but that would be the right solution
for a static-only toolchain I think.

Rich

Re: undefined reference to `raise' with musl static toolchain

[Thomas Petazzoni]

Hello,

On Tue, 8 May 2018 12:34:23 -0400, Rich Felker wrote:

> > It would appear that your version of libgcc references libc. Now, with
> > static linking, the libraries must appear in the correct order to
> > satisfy all dependencies, but here you have a circular dependency between
> > libgcc and libc. Since all gcc compiled code depends on libgcc, and libc
> > is compiled with gcc, there are only two ways to break the cycle:
> > 
> > 1. Remove the dependency. No idea how, not unless you basically inline
> > raise() into __aeabi_idiv0().
> > 
> > 2. Add libc again after the command line.  
> 
> gcc already does this if you pass -static. I suspect the issue is that
> Thomas is using a toolchain where gcc doesn't know it's
> static-linking, and ld only static-links because there's no libc.so
> present. This setup is highly fragile and afaik it's not intended by
> the gcc developers to work. I don't know if there's anything like
> --enable-default-static for gcc but that would be the right solution
> for a static-only toolchain I think.

Indeed, passing -static explicitly fixes the problem.

Without -static:

test@build:~/buildroot$ ./output/host/bin/arm-linux-gcc -o foo foo.c -v
Using built-in specs.
COLLECT_GCC=/home/test/buildroot/output/host/bin/arm-linux-gcc.br_real
COLLECT_LTO_WRAPPER=/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/lto-wrapper
Target: arm-buildroot-linux-musleabihf
Configured with: ./configure --prefix=/home/test/buildroot/output/host --sysconfdir=/home/test/buildroot/output/host/etc --enable-static --target=arm-buildroot-linux-musleabihf --with-sysroot=/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot --disable-__cxa_atexit --with-gnu-ld --disable-libssp --disable-multilib --with-gmp=/home/test/buildroot/output/host --with-mpc=/home/test/buildroot/output/host --with-mpfr=/home/test/buildroot/output/host --with-pkgversion='Buildroot 2018.05-git-01130-gd007bca' --with-bugurl=http://bugs.buildroot.net/ --disable-libmpx --disable-libquadmath --disable-libsanitizer --enable-tls --disable-libmudflap --enable-threads --without-isl --without-cloog --disable-decimal-float --with-abi=aapcs-linux --with-cpu=cortex-a8 --with-fpu=vfpv3-d16 
 --with-float=hard --with-mode=arm --enable-languages=c,c++ --with-build-time-tools=/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/bin --disable-shared --disable-libcilkrts --disable
 -libgomp
Thread model: posix
gcc version 6.4.0 (Buildroot 2018.05-git-01130-gd007bca) 
COLLECT_GCC_OPTIONS='-o' 'foo' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/cc1 -quiet -v -isysroot /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot foo.c -quiet -dumpbase foo.c -mcpu=cortex-a8 -mfloat-abi=hard -mfpu=vfpv3-d16 -mabi=aapcs-linux -marm -mtls-dialect=gnu -auxbase foo -version -o /tmp/cc9R8ARE.s
GNU C11 (Buildroot 2018.05-git-01130-gd007bca) version 6.4.0 (arm-buildroot-linux-musleabihf)
        compiled by GNU C version 4.7.2, GMP version 6.1.2, MPFR version 3.1.6, MPC version 1.0.3, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/usr/local/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/include
 /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/usr/include
 /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/include
End of search list.
GNU C11 (Buildroot 2018.05-git-01130-gd007bca) version 6.4.0 (arm-buildroot-linux-musleabihf)
        compiled by GNU C version 4.7.2, GMP version 6.1.2, MPFR version 3.1.6, MPC version 1.0.3, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 4fc01250e8946128cafb87416e07c618
foo.c: In function 'main':
foo.c:1:18: warning: implicit declaration of function 'mktime' [-Wimplicit-function-declaration]
 int main(void) { mktime(); return 0; }
                  ^~~~~~
COLLECT_GCC_OPTIONS='-o' 'foo' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/bin/as -v -mcpu=cortex-a8 -mfloat-abi=hard -mfpu=vfpv3-d16 -meabi=5 -o /tmp/ccIJ7oOn.o /tmp/cc9R8ARE.s
GNU assembler version 2.29.1 (arm-buildroot-linux-musleabihf) using BFD version (GNU Binutils) 2.29.1
COMPILER_PATH=/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/:/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/:/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/:/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/:/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/:/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/bin/
LIBRARY_PATH=/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/:/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/lib/:/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib/:/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/usr/lib/
COLLECT_GCC_OPTIONS='-o' 'foo' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/collect2 -plugin /home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/liblto_plugin.so -plugin-opt=/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/lto-wrapper -plugin-opt=-fresolution=/tmp/ccHzI6L6.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc --sysroot=/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot --eh-frame-hdr -dynamic-linker /lib/ld-musl-armhf.so.1 -X -m armelf_linux_eabi -o foo /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib/crt1.o /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib/crti.o /home/test/buildroot/out
 put/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/crtbegin.o -L/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0 -L/home/test/buildroot/output/host/lib/gcc/arm-buildr
 oot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/lib -L/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib -L/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/usr/lib /tmp/ccIJ7oOn.o -lgcc -lc -lgcc /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/crtend.o /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib/crtn.o
/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/libgcc.a(_dvmd_lnx.o): In function `__aeabi_idiv0':
/home/test/buildroot/output/build/host-gcc-final-6.4.0/build/arm-buildroot-linux-musleabihf/libgcc/../../../libgcc/config/arm/lib1funcs.S:1354: undefined reference to `raise'
collect2: error: ld returned 1 exit status

With -static:

test@build:~/buildroot$ ./output/host/bin/arm-linux-gcc -o foo foo.c -static -v
Using built-in specs.
COLLECT_GCC=/home/test/buildroot/output/host/bin/arm-linux-gcc.br_real
COLLECT_LTO_WRAPPER=/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/lto-wrapper
Target: arm-buildroot-linux-musleabihf
Configured with: ./configure --prefix=/home/test/buildroot/output/host --sysconfdir=/home/test/buildroot/output/host/etc --enable-static --target=arm-buildroot-linux-musleabihf --with-sysroot=/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot --disable-__cxa_atexit --with-gnu-ld --disable-libssp --disable-multilib --with-gmp=/home/test/buildroot/output/host --with-mpc=/home/test/buildroot/output/host --with-mpfr=/home/test/buildroot/output/host --with-pkgversion='Buildroot 2018.05-git-01130-gd007bca' --with-bugurl=http://bugs.buildroot.net/ --disable-libmpx --disable-libquadmath --disable-libsanitizer --enable-tls --disable-libmudflap --enable-threads --without-isl --without-cloog --disable-decimal-float --with-abi=aapcs-linux --with-cpu=cortex-a8 --with-fpu=vfpv3-d16 
 --with-float=hard --with-mode=arm --enable-languages=c,c++ --with-build-time-tools=/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/bin --disable-shared --disable-libcilkrts --disable
 -libgomp
Thread model: posix
gcc version 6.4.0 (Buildroot 2018.05-git-01130-gd007bca) 
COLLECT_GCC_OPTIONS='-o' 'foo' '-static' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/cc1 -quiet -v -isysroot /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot foo.c -quiet -dumpbase foo.c -mcpu=cortex-a8 -mfloat-abi=hard -mfpu=vfpv3-d16 -mabi=aapcs-linux -marm -mtls-dialect=gnu -auxbase foo -version -o /tmp/ccAsjDgp.s
GNU C11 (Buildroot 2018.05-git-01130-gd007bca) version 6.4.0 (arm-buildroot-linux-musleabihf)
        compiled by GNU C version 4.7.2, GMP version 6.1.2, MPFR version 3.1.6, MPC version 1.0.3, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/usr/local/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/include
 /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/usr/include
 /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/include
End of search list.
GNU C11 (Buildroot 2018.05-git-01130-gd007bca) version 6.4.0 (arm-buildroot-linux-musleabihf)
        compiled by GNU C version 4.7.2, GMP version 6.1.2, MPFR version 3.1.6, MPC version 1.0.3, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 4fc01250e8946128cafb87416e07c618
foo.c: In function 'main':
foo.c:1:18: warning: implicit declaration of function 'mktime' [-Wimplicit-function-declaration]
 int main(void) { mktime(); return 0; }
                  ^~~~~~
COLLECT_GCC_OPTIONS='-o' 'foo' '-static' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/bin/as -v -mcpu=cortex-a8 -mfloat-abi=hard -mfpu=vfpv3-d16 -meabi=5 -o /tmp/ccx5VIfD.o /tmp/ccAsjDgp.s
GNU assembler version 2.29.1 (arm-buildroot-linux-musleabihf) using BFD version (GNU Binutils) 2.29.1
COMPILER_PATH=/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/:/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/:/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/:/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/:/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/:/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/bin/
LIBRARY_PATH=/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/:/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/lib/:/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib/:/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/usr/lib/
COLLECT_GCC_OPTIONS='-o' 'foo' '-static' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/collect2 -plugin /home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/liblto_plugin.so -plugin-opt=/home/test/buildroot/output/host/libexec/gcc/arm-buildroot-linux-musleabihf/6.4.0/lto-wrapper -plugin-opt=-fresolution=/tmp/ccEXBDfR.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc --sysroot=/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot -Bstatic -X -m armelf_linux_eabi -o foo /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib/crt1.o /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib/crti.o /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/crtbeginT.o -L/home/test
 /buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0 -L/home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/../../../../arm-buildroot-linux-musleabihf/lib -L/
 home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib -L/home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/usr/lib /tmp/ccx5VIfD.o --start-group -lgcc -lc --end-group /home/test/buildroot/output/host/lib/gcc/arm-buildroot-linux-musleabihf/6.4.0/crtend.o /home/test/buildroot/output/host/arm-buildroot-linux-musleabihf/sysroot/lib/crtn.o
COLLECT_GCC_OPTIONS='-o' 'foo' '-static' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'

Does this means we *must* pass -static, even if the toolchain only has
the static variant of the C library ?

I'm doing a build to confirm, but I don't think we have the same
requirement with uClibc-ng.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

Re: undefined reference to `raise' with musl static toolchain

[Thomas Petazzoni]

Hello Rich,

On Wed, 9 May 2018 11:29:32 +0200, Thomas Petazzoni wrote:

> I'm doing a build to confirm, but I don't think we have the same
> requirement with uClibc-ng.

A uClibc-ng toolchain works fine without the explicit -static:

test@build:~/outputs/uclibc-static$ cat foo.c 
int main(void) { mktime(); return 0; }
test@build:~/outputs/uclibc-static$ ./host/bin/arm-linux-gcc -o foo foo.c -v
Using built-in specs.
COLLECT_GCC=/home/test/outputs/uclibc-static/host/bin/arm-linux-gcc.br_real
COLLECT_LTO_WRAPPER=/home/test/outputs/uclibc-static/host/libexec/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/lto-wrapper
Target: arm-buildroot-linux-uclibcgnueabihf
Configured with: ./configure --prefix=/home/test/outputs/uclibc-static/host --sysconfdir=/home/test/outputs/uclibc-static/host/etc --enable-static --target=arm-buildroot-linux-uclibcgnueabihf --with-sysroot=/home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot --disable-__cxa_atexit --with-gnu-ld --disable-libssp --disable-multilib --with-gmp=/home/test/outputs/uclibc-static/host --with-mpc=/home/test/outputs/uclibc-static/host --with-mpfr=/home/test/outputs/uclibc-static/host --with-pkgversion='Buildroot 2018.05-git-01130-gd007bca' --with-bugurl=http://bugs.buildroot.net/ --disable-libquadmath --disable-libsanitizer --enable-tls --disable-libmudflap --enable-threads --without-isl --without-cloog --disable-decimal-float --with-abi=aapcs-linux --with-cpu=cortex-a
 8 --with-fpu=vfpv3-d16 --with-float=hard --with-mode=arm --enable-languages=c,c++ --with-build-time-tools=/home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/bin --disable-shar
 ed --disable-libcilkrts --disable-libgomp
Thread model: posix
gcc version 6.4.0 (Buildroot 2018.05-git-01130-gd007bca) 
COLLECT_GCC_OPTIONS='-o' 'foo' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/outputs/uclibc-static/host/libexec/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/cc1 -quiet -v -isysroot /home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot foo.c -quiet -dumpbase foo.c -mcpu=cortex-a8 -mfloat-abi=hard -mfpu=vfpv3-d16 -mabi=aapcs-linux -marm -mtls-dialect=gnu -auxbase foo -version -o /tmp/ccrBk49l.s
GNU C11 (Buildroot 2018.05-git-01130-gd007bca) version 6.4.0 (arm-buildroot-linux-uclibcgnueabihf)
        compiled by GNU C version 4.7.2, GMP version 6.1.2, MPFR version 3.1.6, MPC version 1.0.3, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/local/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/include
 /home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/include-fixed
 /home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/include
 /home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/include
End of search list.
GNU C11 (Buildroot 2018.05-git-01130-gd007bca) version 6.4.0 (arm-buildroot-linux-uclibcgnueabihf)
        compiled by GNU C version 4.7.2, GMP version 6.1.2, MPFR version 3.1.6, MPC version 1.0.3, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 64d3b70b605ed06af58d56698f38a6fa
foo.c: In function 'main':
foo.c:1:18: warning: implicit declaration of function 'mktime' [-Wimplicit-function-declaration]
 int main(void) { mktime(); return 0; }
                  ^~~~~~
COLLECT_GCC_OPTIONS='-o' 'foo' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/bin/as -v -mcpu=cortex-a8 -mfloat-abi=hard -mfpu=vfpv3-d16 -meabi=5 -o /tmp/ccVtxQ2w.o /tmp/ccrBk49l.s
GNU assembler version 2.29.1 (arm-buildroot-linux-uclibcgnueabihf) using BFD version (GNU Binutils) 2.29.1
COMPILER_PATH=/home/test/outputs/uclibc-static/host/libexec/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/:/home/test/outputs/uclibc-static/host/libexec/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/:/home/test/outputs/uclibc-static/host/libexec/gcc/arm-buildroot-linux-uclibcgnueabihf/:/home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/:/home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/:/home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/bin/
LIBRARY_PATH=/home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/:/home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/lib/:/home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/lib/:/home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/lib/
COLLECT_GCC_OPTIONS='-o' 'foo' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
 /home/test/outputs/uclibc-static/host/libexec/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/collect2 -plugin /home/test/outputs/uclibc-static/host/libexec/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/liblto_plugin.so -plugin-opt=/home/test/outputs/uclibc-static/host/libexec/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/lto-wrapper -plugin-opt=-fresolution=/tmp/ccbL5nWH.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc --sysroot=/home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot --eh-frame-hdr -dynamic-linker /lib/ld-uClibc.so.0 -X -m armelf_linux_eabi -o foo /home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/lib/crt1.o /home/test/outputs/uclibc-static/host/arm-buildroot-linux
 -uclibcgnueabihf/sysroot/usr/lib/crti.o /home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/crtbegin.o -L/home/test/outputs/uclibc-static/host/lib/gcc/arm-buildro
 ot-linux-uclibcgnueabihf/6.4.0 -L/home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/lib -L/home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/lib -L/home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/lib /tmp/ccVtxQ2w.o -lgcc -lc -lgcc /home/test/outputs/uclibc-static/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/crtend.o /home/test/outputs/uclibc-static/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/lib/crtn.o
COLLECT_GCC_OPTIONS='-o' 'foo' '-v' '-mcpu=cortex-a8' '-mfloat-abi=hard' '-mfpu=vfpv3-d16' '-mabi=aapcs-linux' '-marm' '-mtls-dialect=gnu'
test@build:~/outputs/uclibc-static$ file foo
foo: ELF 32-bit LSB executable, ARM, version 1 (SYSV), statically linked, not stripped

And the sysroot really only has a static variant of the C library:

test@build:~/outputs/uclibc-static$ ls -l staging/lib staging/usr/lib
staging/lib:
total 68
-rw-r--r-- 1 test test 63630 May  9 09:35 libatomic.a
-rwxr-xr-x 1 test test   962 May  9 09:35 libatomic.la

staging/usr/lib:
total 6368
-rw-r--r-- 1 test test     984 May  9 09:33 crt1.o
-rw-r--r-- 1 test test     992 May  9 09:33 crti.o
-rw-r--r-- 1 test test     976 May  9 09:33 crtn.o
-rw-r--r-- 1 test test 2085880 May  9 09:33 libc.a
-rw-r--r-- 1 test test       8 May  9 09:33 libcrypt.a
-rw-r--r-- 1 test test       8 May  9 09:33 libdl.a
-rw-r--r-- 1 test test       8 May  9 09:33 libiconv.a
-rw-r--r-- 1 test test       8 May  9 09:33 libintl.a
-rw-r--r-- 1 test test       8 May  9 09:33 libm.a
-rw-r--r-- 1 test test       8 May  9 09:33 libnsl.a
-rw-r--r-- 1 test test       8 May  9 09:33 libpthread.a
-rw-r--r-- 1 test test       8 May  9 09:33 libresolv.a
-rw-r--r-- 1 test test       8 May  9 09:33 librt.a
-rw-r--r-- 1 test test 4367292 May  9 09:35 libstdc++.a
-rw-r--r-- 1 test test       8 May  9 09:33 libutil.a

So: why does a musl-based toolchain requires an explicit -static, while
it isn't needed with uClibc-ng ?

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

Re: undefined reference to `raise' with musl static toolchain

[Szabolcs Nagy]

* Thomas Petazzoni <thomas.petazzoni@bootlin.com> [2018-05-09 15:44:07 +0200]:
> 
> So: why does a musl-based toolchain requires an explicit -static, while
> it isn't needed with uClibc-ng ?
> 

there can be many reasons.. 

e.g. if mktime in uclibc-ng happens to reference raise then it
would get linked in independently of libgcc.

or maybe uclibc-ng has its own __aeabi_*div implementation.

or the way libgcc was configured, the raise(SIGFPE) was disabled
(it is only enabled for linux targets, but who knows how
*-linux-uclibcgnueabihf is interpreted).

you can check these using nm/objdump/readelf on libc.a and libgcc.a

Re: undefined reference to `raise' with musl static toolchain

[Rich Felker]

On Wed, May 09, 2018 at 05:24:37PM +0200, Szabolcs Nagy wrote:
> * Thomas Petazzoni <thomas.petazzoni@bootlin.com> [2018-05-09 15:44:07 +0200]:
> > 
> > So: why does a musl-based toolchain requires an explicit -static, while
> > it isn't needed with uClibc-ng ?
> > 
> 
> there can be many reasons.. 
> 
> e.g. if mktime in uclibc-ng happens to reference raise then it
> would get linked in independently of libgcc.
> 
> or maybe uclibc-ng has its own __aeabi_*div implementation.
> 
> or the way libgcc was configured, the raise(SIGFPE) was disabled
> (it is only enabled for linux targets, but who knows how
> *-linux-uclibcgnueabihf is interpreted).
> 
> you can check these using nm/objdump/readelf on libc.a and libgcc.a

It would be nice if this raise dependency could be removed from
libgcc. It's not necessary for any defined behavior; it's only there
for the sake of emulating x86 behavior on div-by-zero.

Either way you need to be using the right link order that -static
gives (potentially for other reasons) but it would be nice to avoid
unnecessary code getting static-linked like this.

Rich

Re: undefined reference to `raise' with musl static toolchain

[Thomas Petazzoni]

Hello,

Thanks for your feedback.

On Wed, 9 May 2018 17:24:37 +0200, Szabolcs Nagy wrote:

> there can be many reasons.. 
> 
> e.g. if mktime in uclibc-ng happens to reference raise then it
> would get linked in independently of libgcc.

In the static binary linked against uClibc, there are two references to
__GI_raise:

	__GI_abort
	__aeabi_idiv0

__GI_abort is reference from _start, so I guess this means that
__GI_abort is always pulled in, therefore __GI_raise is always pulled
in, and __aeabi_idiv0 is happy.

Now my question remains: do you consider it normal that -static is
required, or do you consider it a bug of the musl/gcc integration that
-static is required even when the only variant available of the library
is the static one ?

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

Re: undefined reference to `raise' with musl static toolchain

[Rich Felker]

On Fri, May 11, 2018 at 05:59:01PM +0200, Thomas Petazzoni wrote:
> Hello,
> 
> Thanks for your feedback.
> 
> On Wed, 9 May 2018 17:24:37 +0200, Szabolcs Nagy wrote:
> 
> > there can be many reasons.. 
> > 
> > e.g. if mktime in uclibc-ng happens to reference raise then it
> > would get linked in independently of libgcc.
> 
> In the static binary linked against uClibc, there are two references to
> __GI_raise:
> 
> 	__GI_abort
> 	__aeabi_idiv0
> 
> __GI_abort is reference from _start, so I guess this means that
> __GI_abort is always pulled in, therefore __GI_raise is always pulled
> in, and __aeabi_idiv0 is happy.
> 
> Now my question remains: do you consider it normal that -static is
> required, or do you consider it a bug of the musl/gcc integration that
> -static is required even when the only variant available of the library
> is the static one ?

I don't think gcc is intended to work right in configurations where it
supports dynamic linking but the only libc available is static, unless
you pass -static, and I don't see a good way to make it work in that
case. You've only hit the tip of the iceberg; there's more stuff that
could break subtly when gcc is passing ld options that were intended
for dynamic linking, but ld actually ends up performing static
linking. It "working" with uClibc is just "getting lucky" (or
"unlucky" depending on your perspective about ignoring vs catching
unsafe things).

If gcc doesn't have any option to tell it you're building a
static-only toolchain and make static linking the default, I see that
as something of an omission, and maybe we should try to get that added
to gcc.

Rich

Re: undefined reference to `raise' with musl static toolchain

[Thomas Petazzoni]

Hello,

Thanks for your feedback!

On Fri, 11 May 2018 12:05:44 -0400, Rich Felker wrote:

> > Now my question remains: do you consider it normal that -static is
> > required, or do you consider it a bug of the musl/gcc integration that
> > -static is required even when the only variant available of the library
> > is the static one ?  
> 
> I don't think gcc is intended to work right in configurations where it
> supports dynamic linking but the only libc available is static, unless
> you pass -static, and I don't see a good way to make it work in that
> case. You've only hit the tip of the iceberg; there's more stuff that
> could break subtly when gcc is passing ld options that were intended
> for dynamic linking, but ld actually ends up performing static
> linking. It "working" with uClibc is just "getting lucky" (or
> "unlucky" depending on your perspective about ignoring vs catching
> unsafe things).

OK.

> If gcc doesn't have any option to tell it you're building a
> static-only toolchain and make static linking the default, I see that
> as something of an omission, and maybe we should try to get that added
> to gcc.

I don't see anything like that. Buildroot already builds gcc with
--enable-static --disable-shared when building a static toolchain, and
I don't see any other option that would be relevant, from a quick look.

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com