topic Re: Creating a shared object in Operating System - HP-UX

Creating a shared object

devshlom — Wed, 11 Jun 2008 06:41:58 GMT

Hi,
I have to create a shared object (so) on HP-UX.
I already have a Makefile that does it for all the other unix platforms (aix, linux, solaris)
1. what should to make it work on HP?
2. can one of you give me a working and small example for a Makefile that creates a shared object?

tx,
shlom

Re: Creating a shared object

Fabien GUTIERREZ — Wed, 11 Jun 2008 06:54:14 GMT

on pa-risc shared library are designed as .sl files and on integrity servers as .so files
you can refer to this external link to find examples of compile and linking options

http://www.franz.com/support/documentation/current/doc/foreign-functions.htm#ff-on-hp-1

Re: Creating a shared object

Dennis Handly — Wed, 11 Jun 2008 07:56:24 GMT

On HP-UX these are called shared libraries.
Here is the Linker Online Help:
http://docs.hp.com/en/11782/LinkerOnliinehelp0709/creatingandusinglibraries.htm

Creating shlibs is pretty simple:
libfoo.so: foo.o
$(CC) -b -o $@ foo.o

foo.o: foo.c
$(CC) -c foo.c

If you are on PA, change to ".sl" and add +z to the compile line.

Re: Creating a shared object

devshlom — Wed, 11 Jun 2008 09:44:57 GMT

hi dennis,
tx again for your answers.

Sorry for the beginner questions - I still new to this platforms...
1. how do I know if I'm working on PA? when I run uname -a I get: "HP-UX hpux B.11.23 U 9000/800 3697136004 unlimited-user license"

2. When I add +Z to the compile command I get: "gcc: +Z: No such file or directory"

3. In your example:
- you put "-b" what this option stands for?
- should I used also "-shared"?

As you see, I'm a little confused here - if you make it simple for me I will be grateful.

my gcc is: (gcc -v)
Using built-in specs.
Target: hppa2.0w-hp-hpux11.23
Configured with: ../gcc/configure
Thread model: posix
gcc version 4.2.2

tx!!!
shlom

Re: Creating a shared object

Dennis Handly — Wed, 11 Jun 2008 10:05:45 GMT

>1. how do I know if I'm working on PA? when I run uname -a I get: "HP-UX hpux B.11.23 U 9000/800

This is PA. Otherwise it says ia64 for Integrity.

>2. When I add +Z to the compile command I get: "gcc: +Z: No such file or directory"
>my gcc is:

Ah, you are using a foreign devil compiler.
You need -fpic.

>- you put "-b" what this option stands for?
>- should I used also "-shared"?

-b is the linker and HP's compiler option to create shlibs.
Yes, replace by -shared for gcc.

Re: Creating a shared object

devshlom — Wed, 11 Jun 2008 10:21:52 GMT

so,
after we both know what I'm working on,pls see the reason I got confused
when I use the following:
"$(CC) -shared -fpic -o $@ $(OBJ) ...", I get this weird msg:
/usr/ccs/bin/ld: CODE_ONE_SYM fixup to non-code subspace in file /home/s/import/so/TestSo/TestSo/debug/HPUX-Risc/test.o - shared library must be position independent. Use +z or +Z to recompile.
collect2: ld returned 1 exit status

so? how can I prevent this?

tx

Re: Creating a shared object

Dennis Handly — Wed, 11 Jun 2008 10:29:37 GMT

>ld: CODE_ONE_SYM fixup to non-code subspace in file test.o - shared library must be position independent. Use +z or +Z to recompile.
>how can I prevent this?

Was test.o compiled with -fpic?

Re: Creating a shared object

devshlom — Wed, 11 Jun 2008 12:16:27 GMT

tx dennis,

yes - the object did compile with the -fpic!!!
1. I succeeded create the sample so (the small one) - but the big one still doesn't work (even with the -fPIC)

2. another question:
after knowing how to generate a shared object, what is the standard for its extension? should I use ".sl" instead of ".so"

tx

Re: Creating a shared object

Dennis Handly — Thu, 12 Jun 2008 02:44:31 GMT

>yes - the object did compile with the -fpic!!

That's not what the linker says. So either you didn't or gcc is broken.
If you want to attach a copy of test.o, I can look at it.

>1. but the big one still doesn't work

The above linker error? Or something else?

>2. what is the standard for its extension? should I use ".sl" instead of ".so"

On PA you use .sl. On IPF you use .sl.

Re: Creating a shared object

devshlom — Thu, 12 Jun 2008 06:18:37 GMT

Hi again,

1. After I added -fpic to both compilation and linkage the test shared object was created!!!

2. The big program that I mentioned before is my real shared object (not the tester)that I have to create - here is the error I get:
/usr/ccs/bin/ld: Invalid loader fixup in text space needed in output file for symbol "CClassName::~CClassName()" in input file "/home/s/lib_somelib.a(Someobject.o)"
collect2: ld returned 1 exit status
this is the first time I get such error - any idea? is it something to do with the extenal lib that is linked with the shared object? any idea?

3. when I run file on the tester shared object I get the following result:
"libtest.so:PA-RISC2.0 shared library -not stripped" - I think it's ok - what do say?

4. according to what you said before, I will have to change the extesion to "sl" - don't I?

tx a lot!
shlom

Re: Creating a shared object

Dennis Handly — Thu, 12 Jun 2008 06:44:41 GMT

>ld: Invalid loader fixup in text space needed in output file for symbol "CClassName::~CClassName()" in Someobject.o

This the same missing PIC option or g++ is broken.

>is it something to do with the external lib that is linked with the shared object?

Probably not.

>libtest.so: PA-RISC2.0 shared library
> I think it's ok

Yes, this is fine

>4. I will have to change the extension to "sl" - don't I?

You don't "have" to but it is a good idea.
Otherwise ld won't find it with -ltest without extra work.

Re: Creating a shared object

devshlom — Thu, 12 Jun 2008 10:13:32 GMT

hi,

about the PIC/pic:
-------------------
is there any difference between "-fPIC" to "-fpic"?

Re: Creating a shared object

Dennis Handly — Thu, 12 Jun 2008 21:30:34 GMT

>is there any difference between "-fPIC" to "-fpic"?

There is a difference between +z and +Z, it is possible that gcc has the same?

Basically +Z is needed for load modules that have lots of symbols. You only need it if the linker runs out of short addressing space for the linkage table.

Re: Creating a shared object

devshlom — Sun, 15 Jun 2008 12:53:04 GMT

Hi,

As I mentioned before I succeeded in compiling and linking my simple tester and create the sl.
But when I tried to link it with another lib (archive) I failed unless I add "-fpic" also to this lib compilation.
1. Is this ok?!
2. Does it mean that all the libraries that should be linked with the shared object must be compiled also with "-fpic"?
3. Another fact I not sure of:
when I used GCC_PATH=`gcc -print-file-name=libstdc++.a" I still fail. BUT when GCC_PATH=-lstdc++ it works!

tx in advance!

Re: Creating a shared object

Dennis Handly — Sun, 15 Jun 2008 13:01:30 GMT

>But when I tried to link it with another lib (archive) I failed unless I add "-fpic" also to this lib compilation.
>2. Does it mean that all the libraries that should be linked with the shared lib must be compiled also with "-fpic"?

Yes, ALL objects in a shlib must be compiled as PIC.

>3. Another fact I not sure of: when I used GCC_PATH=`gcc -print-file-name=libstdc++.a" I still fail. BUT when GCC_PATH=-lstdc++ it works!

No clue, What was GCC_PATH set too? Go with what works.

Re: Creating a shared object

devshlom — Sun, 15 Jun 2008 13:43:57 GMT

tx again.

so, for using this shared object:

I have object libmytest.sl
I need to create some exe that uses this shared lib.

1. should I put this on /usr/lib/ or there is another standard in HP?

2. should I set LD_LIBRARY_PATH to this location - or there are some equivaent environment variable for the linker to search for shared objects?

Re: Creating a shared object

devshlom — Sun, 15 Jun 2008 13:51:03 GMT

and also important:

the link line:

gcc -o tester -ltestmyso -L$(BUILD_DIR) $(OBJ)-lpthread

is this ok??

tx.

Re: Creating a shared object

Dennis Handly — Sun, 15 Jun 2008 14:09:55 GMT

>1. should I put this on /usr/lib/ or there is another standard in HP?

That's the PA HP-UX default for HP's products.
There is no reason you can't put your stuff there. But you could also put your shlib with your executable or some parallel lib/ directory. It may depend on how many executables use that shlib and if they are all in the same directory structure.

>2. should I set LD_LIBRARY_PATH to this location - or there are some equivalent environment variable for the linker to search for shared libs?

For PA32, you need to use SHLIB_PATH for dld to find it. Or you can hardcode the path at link time with -Wl,+b,path.

>the link line: gcc -ltestmyso -L$(BUILD_DIR) $(OBJ)-lpthread
>is this ok??

You need a space between "$(OBJ)" and -lpthread.
And -L should come before its -llibs.

Re: Creating a shared object

devshlom — Sun, 15 Jun 2008 14:20:11 GMT

tx again.

finally my sample works well also with external libs!!! so this is a good progress.

now.. back to the real project:
I need to find a way (if exists) to make my so link with no errors with minimal changes => instead of changing all the libs Makefiles (that my slib needs) to use "-fpic"
=> can I put some linker flag in my sl makefile that makes it link well?! (if I don't have a choice, I will so this change only for HPUX but this is the last option)

tx

Re: Creating a shared object

Dennis Handly — Sun, 15 Jun 2008 14:56:44 GMT

>I need to find a way to make my so link with no errors with minimal changes => instead of changing all the libs Makefiles (that my slib needs) to use "-fpic"
>=> can I put some linker flag in my sl makefile that makes it link well?

This is a compile option, not link.
If you were using HP's compiler you could just export CCOPTS="+z" and then do the make.

I don't know if gcc has something similar?
But well designed makefiles allow you to add options on the command lines or have centralized make include files where you can change this all in one place.