[Xenomai] Cannot create a share library linked against Xenomai libs

[Xenomai] Cannot create a share library linked against Xenomai libs

[Leopold Palomo-Avellaneda]

Hi,


I'm trying to build a shared library, using the posix skin with Xenomai 3.0.3. 
I have built xenomai with:

'--with-core=cobalt' '--enable-smp' '--enable-pshared' '--enable-fortify' 
'--enable-shared

I built withour any error. However, when I try to build a library (shared) 
that uses xenomai I got this error:

/usr/bin/ld: /usr/xenomai/lib/xenomai/bootstrap.o: relocation R_X86_64_32 
against `.rodata.str1.1' can not be used when making a shared object; 
recompile with -fPIC

Static libs build perfect. 

Any idea,

Best regards,

Leopold


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Re: [Xenomai] Cannot create a share library linked against Xenomai libs

[dietmar.schindler]

> Von: Xenomai [mailto:xenomai-bounces@xenomai.org] Im Auftrag von Leopold Palomo-Avellaneda
> Gesendet: Montag, 19. September 2016 22:45
>
> I'm trying to build a shared library, using the posix skin with Xenomai 3.0.3.
> I have built xenomai with:
>
> '--with-core=cobalt' '--enable-smp' '--enable-pshared' '--enable-fortify'
> '--enable-shared
>
> I built withour any error. However, when I try to build a library (shared)
> that uses xenomai I got this error:
>
> /usr/bin/ld: /usr/xenomai/lib/xenomai/bootstrap.o: relocation R_X86_64_32
> against `.rodata.str1.1' can not be used when making a shared object;
> recompile with -fPIC

Here is an answer to a similar problem: http://stackoverflow.com/a/38431538/2413201
It says to use the compiler flags -Wformat=0 or/and -Wno-format-security; perhaps it helps also in your case.
--
Best regards,
Dietmar
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Re: [Xenomai] Cannot create a share library linked against Xenomai libs

[Leopold Palomo-Avellaneda]

El Dimarts, 20 de setembre de 2016, a les 06:18:45, 
dietmar.schindler@manroland-web.com va escriure:
> > Von: Xenomai [mailto:xenomai-bounces@xenomai.org] Im Auftrag von Leopold
> > Palomo-Avellaneda Gesendet: Montag, 19. September 2016 22:45
> > 
> > I'm trying to build a shared library, using the posix skin with Xenomai
> > 3.0.3. I have built xenomai with:
> > 
> > '--with-core=cobalt' '--enable-smp' '--enable-pshared' '--enable-fortify'
> > '--enable-shared
> > 
> > I built withour any error. However, when I try to build a library (shared)
> > that uses xenomai I got this error:
> > 
> > /usr/bin/ld: /usr/xenomai/lib/xenomai/bootstrap.o: relocation R_X86_64_32
> > against `.rodata.str1.1' can not be used when making a shared object;
> > recompile with -fPIC
> 
> Here is an answer to a similar problem:
> http://stackoverflow.com/a/38431538/2413201 It says to use the compiler
> flags -Wformat=0 or/and -Wno-format-security; perhaps it helps also in your
> case. --

Thanks,

but not. I have tried in both cases: recompiling my lib and xenomai. Still 
getting the same error.

What surprises me more is that with 2.6.x I have no error but with 3.x I get 
it. 

Best regards,

Leopold

-- 
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A: Top-posting.
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Re: [Xenomai] Cannot create a share library linked against Xenomai libs

[Philippe Gerum]

On 09/19/2016 10:45 PM, Leopold Palomo-Avellaneda wrote:
> Hi,
> 
> 
> I'm trying to build a shared library, using the posix skin with Xenomai 3.0.3. 
> I have built xenomai with:
> 
> '--with-core=cobalt' '--enable-smp' '--enable-pshared' '--enable-fortify' 
> '--enable-shared
> 
> I built withour any error. However, when I try to build a library (shared) 
> that uses xenomai I got this error:
> 
> /usr/bin/ld: /usr/xenomai/lib/xenomai/bootstrap.o: relocation R_X86_64_32 
> against `.rodata.str1.1' can not be used when making a shared object; 
> recompile with -fPIC
> 
> Static libs build perfect. 
> 
> Any idea,
> 
> Best regards,
> 
> Leopold
> 
> 

You may want to check --auto-init-solib from xeno-config:

http://www.xenomai.org/documentation/xenomai-3/html/man1/xeno-config/index.html

-- 
Philippe.

Re: [Xenomai] Cannot create a share library linked against Xenomai libs

[Philippe Gerum]

On 09/20/2016 08:37 AM, Leopold Palomo-Avellaneda wrote:
> El Dimarts, 20 de setembre de 2016, a les 06:18:45, 
> dietmar.schindler@manroland-web.com va escriure:
>>> Von: Xenomai [mailto:xenomai-bounces@xenomai.org] Im Auftrag von Leopold
>>> Palomo-Avellaneda Gesendet: Montag, 19. September 2016 22:45
>>>
>>> I'm trying to build a shared library, using the posix skin with Xenomai
>>> 3.0.3. I have built xenomai with:
>>>
>>> '--with-core=cobalt' '--enable-smp' '--enable-pshared' '--enable-fortify'
>>> '--enable-shared
>>>
>>> I built withour any error. However, when I try to build a library (shared)
>>> that uses xenomai I got this error:
>>>
>>> /usr/bin/ld: /usr/xenomai/lib/xenomai/bootstrap.o: relocation R_X86_64_32
>>> against `.rodata.str1.1' can not be used when making a shared object;
>>> recompile with -fPIC
>>
>> Here is an answer to a similar problem:
>> http://stackoverflow.com/a/38431538/2413201 It says to use the compiler
>> flags -Wformat=0 or/and -Wno-format-security; perhaps it helps also in your
>> case. --
> 
> Thanks,
> 
> but not. I have tried in both cases: recompiling my lib and xenomai. Still 
> getting the same error.
> 
> What surprises me more is that with 2.6.x I have no error but with 3.x I get 
> it. 
> 

2.6.x did not have any bootstrap module, which explains the difference.

-- 
Philippe.

Re: [Xenomai] Cannot create a share library linked against Xenomai libs

[Leopold Palomo-Avellaneda]

El Dimarts, 20 de setembre de 2016, a les 09:04:55, Philippe Gerum va 
escriure:
> On 09/19/2016 10:45 PM, Leopold Palomo-Avellaneda wrote:
> > Hi,
> > 
> > 
> > I'm trying to build a shared library, using the posix skin with Xenomai
> > 3.0.3. I have built xenomai with:
> > 
> > '--with-core=cobalt' '--enable-smp' '--enable-pshared' '--enable-fortify'
> > '--enable-shared
> > 
> > I built withour any error. However, when I try to build a library (shared)
> > that uses xenomai I got this error:
> > 
> > /usr/bin/ld: /usr/xenomai/lib/xenomai/bootstrap.o: relocation R_X86_64_32
> > against `.rodata.str1.1' can not be used when making a shared object;
> > recompile with -fPIC
> > 
> > Static libs build perfect.
> > 
> > Any idea,
> > 
> > Best regards,
> > 
> > Leopold
> 
> You may want to check --auto-init-solib from xeno-config:
> 
> http://www.xenomai.org/documentation/xenomai-3/html/man1/xeno-config/index.h
> tml

I partially solved the problem but your email worries me more. First of all 
because in 3.0.2 that option was not there. And it's an important issue.

Second, because you make a difference between creating a executable and create 
a shared library and I don't know if we have a lot of benefits making that 
distinction. Gcc documentation explain:

"If supported for the target machine, emit position-independent code, suitable 
for dynamic linking and avoiding any limit on the size of the global offset 
table. This option makes a difference on AArch64, m68k, PowerPC and SPARC."


And lastly, although the first error is solved, I got another error:

Linking C shared library libsoem_rt.so
/usr/bin/cmake -E cmake_link_script CMakeFiles/soem_dynamic_rt.dir/link.txt --
verbose=1
/usr/bin/cc  -fPIC -D_FORTIFY_SOURCE=2 -Wno-format-security -Wformat=0 -O2 -g 
-DNDEBUG -Wl,@/usr/xenomai/lib/cobalt.wrappers 
/usr/xenomai/lib/xenomai/bootstrap.o -Wl,--wrap=main -Wl,--dynamic-
list=/usr/xenomai/lib/dynlist.ld -Wl,--no-undefined -shared -Wl,-
soname,libsoem_rt.so.1 -o libsoem_rt.so.1.3 
CMakeFiles/soem_dynamic_rt.dir/soem/ethercatdc.c.o 
CMakeFiles/soem_dynamic_rt.dir/soem/ethercatfoe.c.o 
CMakeFiles/soem_dynamic_rt.dir/soem/ethercatmain.c.o 
CMakeFiles/soem_dynamic_rt.dir/soem/ethercatprint.c.o 
CMakeFiles/soem_dynamic_rt.dir/soem/ethercatconfig.c.o 
CMakeFiles/soem_dynamic_rt.dir/soem/ethercatsoe.c.o 
CMakeFiles/soem_dynamic_rt.dir/soem/ethercatbase.c.o 
CMakeFiles/soem_dynamic_rt.dir/soem/ethercatcoe.c.o 
CMakeFiles/soem_dynamic_rt.dir/osal/linux/osal.c.o 
CMakeFiles/soem_dynamic_rt.dir/oshw/linux/nicdrv.c.o 
CMakeFiles/soem_dynamic_rt.dir/oshw/linux/oshw.c.o -L/usr/xenomai/lib -lcobalt 
-lpthread -lrt 
/usr/xenomai/lib/xenomai/bootstrap.o: In function `xenomai_main':
bootstrap.c:(.text+0x2c): undefined reference to `main'
bootstrap.c:(.text+0x40): undefined reference to `main'
collect2: error: ld returned 1 exit status


so, the POSIX script to build a POSIX code fails when you wants to build a 
shared library. Dropping "-Wl,--wrap=main " the library is built.

So, from my point of view, xeno-config is not giving an accurate answer and the 
--auto-init-solib doesn't help too much. I would like to propose this:

as --[no-]auto-init is meaningful only with --ldflags, and to link against (*)-
pic is for shared libraries I would add an option to xeno-config, --ldflags-
shared, or --ldflags-shared-libs where /usr/xenomai/lib/xenomai/bootstrap-pic.o 
i set and "-Wl,--wrap=main" is dropped.

What do you think?

Leopold



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Re: [Xenomai] Cannot create a share library linked against Xenomai libs

[Philippe Gerum]

On 09/20/2016 12:56 PM, Leopold Palomo-Avellaneda wrote:
> El Dimarts, 20 de setembre de 2016, a les 09:04:55, Philippe Gerum va 
> escriure:
>> You may want to check --auto-init-solib from xeno-config:
>>
>> http://www.xenomai.org/documentation/xenomai-3/html/man1/xeno-config/index.h
>> tml
> 
> I partially solved the problem but your email worries me more. First of all 
> because in 3.0.2 that option was not there. And it's an important issue.

Improvements in software do happen, including with new versions.
Besides, you mentioned 3.0.3 as being your current version.

This option is a shorthand for people with a very specific requirement
for building a shared library with Xenomai auto-init capabilities,
instead of crafting an obscure set of link flags manually for this
purpose. The intended use case is about having a regular executable not linked with Xenomai libs, but using the dlopen() interface to attach Xenomai-dependent libs dynamically at runtime, in which case one may want the latter to kick the Xenomai services transparently when loaded.

Reading your proposal, I'm now wondering whether building a
shared library of that sort with automatic Xenomai bootstrap is your goal. Is it?

> 
> Second, because you make a difference between creating a executable and create 
> a shared library and I don't know if we have a lot of benefits making that 
> distinction. Gcc documentation explain:
> 
> "If supported for the target machine, emit position-independent code, suitable 
> for dynamic linking and avoiding any limit on the size of the global offset 
> table. This option makes a difference on AArch64, m68k, PowerPC and SPARC."
> 

I don't get your point. Xenomai supports two of those architectures, and
you could add blackfin to that list, so this is not a matter of benefit,
this is a matter of requirement.

> 
> And lastly, although the first error is solved,

Which illustrates the benefit of emiting PIC when required, otherwise one gets relocation errors as you observed.

 I got another error:
> 
> Linking C shared library libsoem_rt.so
> /usr/bin/cmake -E cmake_link_script CMakeFiles/soem_dynamic_rt.dir/link.txt --
> verbose=1
> /usr/bin/cc  -fPIC -D_FORTIFY_SOURCE=2 -Wno-format-security -Wformat=0 -O2 -g 
> -DNDEBUG -Wl,@/usr/xenomai/lib/cobalt.wrappers 
> /usr/xenomai/lib/xenomai/bootstrap.o -Wl,--wrap=main -Wl,--dynamic-
> list=/usr/xenomai/lib/dynlist.ld -Wl,--no-undefined -shared -Wl,-
> soname,libsoem_rt.so.1 -o libsoem_rt.so.1.3 
> CMakeFiles/soem_dynamic_rt.dir/soem/ethercatdc.c.o 
> CMakeFiles/soem_dynamic_rt.dir/soem/ethercatfoe.c.o 
> CMakeFiles/soem_dynamic_rt.dir/soem/ethercatmain.c.o 
> CMakeFiles/soem_dynamic_rt.dir/soem/ethercatprint.c.o 
> CMakeFiles/soem_dynamic_rt.dir/soem/ethercatconfig.c.o 
> CMakeFiles/soem_dynamic_rt.dir/soem/ethercatsoe.c.o 
> CMakeFiles/soem_dynamic_rt.dir/soem/ethercatbase.c.o 
> CMakeFiles/soem_dynamic_rt.dir/soem/ethercatcoe.c.o 
> CMakeFiles/soem_dynamic_rt.dir/osal/linux/osal.c.o 
> CMakeFiles/soem_dynamic_rt.dir/oshw/linux/nicdrv.c.o 
> CMakeFiles/soem_dynamic_rt.dir/oshw/linux/oshw.c.o -L/usr/xenomai/lib -lcobalt 
> -lpthread -lrt 
> /usr/xenomai/lib/xenomai/bootstrap.o: In function `xenomai_main':
> bootstrap.c:(.text+0x2c): undefined reference to `main'
> bootstrap.c:(.text+0x40): undefined reference to `main'
> collect2: error: ld returned 1 exit status
> 
> 
> so, the POSIX script to build a POSIX code fails when you wants to build a 
> shared library. Dropping "-Wl,--wrap=main " the library is built.
> 
> So, from my point of view, xeno-config is not giving an accurate answer and the 
> --auto-init-solib doesn't help too much. I would like to propose this:
> 
> as --[no-]auto-init is meaningful only with --ldflags, and to link against (*)-
> pic is for shared libraries I would add an option to xeno-config, --ldflags-
> shared, or --ldflags-shared-libs where /usr/xenomai/lib/xenomai/bootstrap-pic.o 
> i set and "-Wl,--wrap=main" is dropped.
> 
> What do you think?
> 

Using --auto-init-solib is not about building a generic shared library,
there is nothing Xenomai-specific in doing so, and it's not
xeno-config's business to determine the right ldflags for this.

xeno-config is the documented way to retrieve the extra flags required to compile and link object files for which dependencies on Xenomai exist. --auto-init-solib extends this by providing a shorthand for retrieving the additional ldflags required for including a version of the _bootstrap_ code suitable for a shared library, so that e.g. Cobalt binding code runs when the library is dlopened, or the Copperplate layer automatically initializes before a non-POSIX API is used.

So the issue is not with xeno-config lacking yet another switch for
specifically linking shared libraries in general, but with
--auto-init-solib wrongly trying to wrap the main symbol when turning on
the automatic bootstrap mode, which it should only do with plain
executables. As a corollary, the bootstrap module should not create any reference to the main() routine when built for a shared library,

i.e something along these lines:

diff --git a/scripts/xeno-config-cobalt.in b/scripts/xeno-config-cobalt.in
index 38f8208..802b778 100644
--- a/scripts/xeno-config-cobalt.in
+++ b/scripts/xeno-config-cobalt.in
@@ -262,10 +262,14 @@ if test x$do_ldflags = xy; then
     done
     wrap_main=
     if test x$do_autoinit = xy; then
-	test x$do_autoinit_solib = xy && codegen=-pic
-	wrap_main="${XENO_LIBRARY_DIR}/xenomai/bootstrap${codegen}.o
-Wl,--wrap=main -Wl,--dynamic-list=${XENO_LIBRARY_DIR}/dynlist.ld"
+	if test x$do_autoinit_solib = xy; then
+	    codegen=-pic
+	else
+	    wrap_main="-Wl,--wrap=main
-Wl,--dynamic-list=${XENO_LIBRARY_DIR}/dynlist.ld"
+	fi
+	bootstrap="${XENO_LIBRARY_DIR}/xenomai/bootstrap${codegen}.o"
     fi
-    echo "$ldflags $copperplate $wrap_main $XENO_POSIX_LDFLAGS"
+    echo "$ldflags $copperplate $bootstrap $wrap_main $XENO_POSIX_LDFLAGS"
 fi

 exit 0

diff --git a/lib/boilerplate/init/bootstrap.c b/lib/boilerplate/init/bootstrap.c
index 119b405..b0d4a12 100644
--- a/lib/boilerplate/init/bootstrap.c
+++ b/lib/boilerplate/init/bootstrap.c
@@ -28,6 +28,8 @@ static char *const *early_argv;
 
 const int xenomai_auto_bootstrap = 1;
 
+#ifndef __PIC__
+
 int __real_main(int argc, char *const argv[]);
 
 int __wrap_main(int argc, char *const argv[])
@@ -43,6 +45,8 @@ int xenomai_main(int argc, char *const argv[])
 	return __real_main(argc, argv);
 }
 
+#endif /* !__PIC__ */
+
 __bootstrap_ctor static void xenomai_bootstrap(void)
 {
 	char *arglist, *argend, *p, **v, *const *argv;
-- 
Philippe.

Re: [Xenomai] Cannot create a share library linked against Xenomai libs

[Leopold Palomo-Avellaneda]

El Dimecres, 21 de setembre de 2016, a les 10:30:43, Philippe Gerum va 
escriure:

[...]
> 
> This option is a shorthand for people with a very specific requirement
> for building a shared library with Xenomai auto-init capabilities,

just to build a shared library. This is new form Xenomai 3

> instead of crafting an obscure set of link flags manually for this
> purpose. The intended use case is about having a regular executable not
> linked with Xenomai libs, but using the dlopen() interface to attach
> Xenomai-dependent libs dynamically at runtime, in which case one may want
> the latter to kick the Xenomai services transparently when loaded.
> 
> Reading your proposal, I'm now wondering whether building a
> shared library of that sort with automatic Xenomai bootstrap is your goal.
> Is it?

Yes, to build a shared library using Xenomai stuff in the way that a user of 
hat library (developer) just need to know some minimal knowledge of Xenomai.

> > Second, because you make a difference between creating a executable and
> > create a shared library and I don't know if we have a lot of benefits
> > making that distinction. Gcc documentation explain:
> > 
> > "If supported for the target machine, emit position-independent code,
> > suitable for dynamic linking and avoiding any limit on the size of the
> > global offset table. This option makes a difference on AArch64, m68k,
> > PowerPC and SPARC."
> I don't get your point. Xenomai supports two of those architectures, and
> you could add blackfin to that list, so this is not a matter of benefit,
> this is a matter of requirement.

I'm sorry, maybe I was confused. I followed several threads in debian-devel 
about to add this option by default [1], [2],[3] [4]. However, Debian is a 
general linux distro and Xenomai has a different target. 

> > And lastly, although the first error is solved,
> 
> Which illustrates the benefit of emiting PIC when required, otherwise one
> gets relocation errors as you observed.
>  I got another error:
> > Linking C shared library libsoem_rt.so
> > /usr/bin/cmake -E cmake_link_script
> > CMakeFiles/soem_dynamic_rt.dir/link.txt -- verbose=1
> > /usr/bin/cc  -fPIC -D_FORTIFY_SOURCE=2 -Wno-format-security -Wformat=0 -O2
> > -g -DNDEBUG -Wl,@/usr/xenomai/lib/cobalt.wrappers
> > /usr/xenomai/lib/xenomai/bootstrap.o -Wl,--wrap=main -Wl,--dynamic-
> > list=/usr/xenomai/lib/dynlist.ld -Wl,--no-undefined -shared -Wl,-
> > soname,libsoem_rt.so.1 -o libsoem_rt.so.1.3
> > CMakeFiles/soem_dynamic_rt.dir/soem/ethercatdc.c.o
> > CMakeFiles/soem_dynamic_rt.dir/soem/ethercatfoe.c.o
> > CMakeFiles/soem_dynamic_rt.dir/soem/ethercatmain.c.o
> > CMakeFiles/soem_dynamic_rt.dir/soem/ethercatprint.c.o
> > CMakeFiles/soem_dynamic_rt.dir/soem/ethercatconfig.c.o
> > CMakeFiles/soem_dynamic_rt.dir/soem/ethercatsoe.c.o
> > CMakeFiles/soem_dynamic_rt.dir/soem/ethercatbase.c.o
> > CMakeFiles/soem_dynamic_rt.dir/soem/ethercatcoe.c.o
> > CMakeFiles/soem_dynamic_rt.dir/osal/linux/osal.c.o
> > CMakeFiles/soem_dynamic_rt.dir/oshw/linux/nicdrv.c.o
> > CMakeFiles/soem_dynamic_rt.dir/oshw/linux/oshw.c.o -L/usr/xenomai/lib
> > -lcobalt -lpthread -lrt
> > /usr/xenomai/lib/xenomai/bootstrap.o: In function `xenomai_main':
> > bootstrap.c:(.text+0x2c): undefined reference to `main'
> > bootstrap.c:(.text+0x40): undefined reference to `main'
> > collect2: error: ld returned 1 exit status
> > 
> > 
> > so, the POSIX script to build a POSIX code fails when you wants to build a
> > shared library. Dropping "-Wl,--wrap=main " the library is built.
> > 
> > So, from my point of view, xeno-config is not giving an accurate answer
> > and the --auto-init-solib doesn't help too much. I would like to propose
> > this:
> > 
> > as --[no-]auto-init is meaningful only with --ldflags, and to link against
> > (*)- pic is for shared libraries I would add an option to xeno-config,
> > --ldflags- shared, or --ldflags-shared-libs where
> > /usr/xenomai/lib/xenomai/bootstrap-pic.o i set and "-Wl,--wrap=main" is
> > dropped.
> > 
> > What do you think?
> 
> Using --auto-init-solib is not about building a generic shared library,
> there is nothing Xenomai-specific in doing so, and it's not
> xeno-config's business to determine the right ldflags for this.
> 

Sorry, I misunderstand the documentation. From here [5]

This switch enables the auto-initialization feature described above for a 
shared library target instead of a pure executable. 

I understood that it was for building a shared library.

> xeno-config is the documented way to retrieve the extra flags required to
> compile and link object files for which dependencies on Xenomai exist.
> --auto-init-solib extends this by providing a shorthand for retrieving the
> additional ldflags required for including a version of the _bootstrap_ code
> suitable for a shared library, so that e.g. Cobalt binding code runs when
> the library is dlopened, or the Copperplate layer automatically initializes
> before a non-POSIX API is used.
> 
> So the issue is not with xeno-config lacking yet another switch for
> specifically linking shared libraries in general, but with
> --auto-init-solib wrongly trying to wrap the main symbol when turning on
> the automatic bootstrap mode, which it should only do with plain
> executables. As a corollary, the bootstrap module should not create any
> reference to the main() routine when built for a shared library,

well, there's a bug here. I'm agree that  --auto-init-solib should not wrap 
the main symbol.

> i.e something along these lines:
> 
> diff --git a/scripts/xeno-config-cobalt.in b/scripts/xeno-config-cobalt.in
> index 38f8208..802b778 100644

[...]


yes, the patch worked. Now it compiled and links. Please could you push it?

Thanks,

Leopold
---

[1] https://lists.debian.org/debian-devel/2016/05/msg00028.html
[2] https://lists.debian.org/debian-devel/2016/05/msg00228.html
[3] https://lists.debian.org/debian-devel/2016/05/msg00306.html
[4] https://lists.debian.org/debian-devel/2016/09/msg00217.html
[5] http://www.xenomai.org/documentation/xenomai-3/html/man1/xeno-config/index.html


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