Re: Compilation problems on Ubuntu 64-bit

Hi,


Kai Ruottu wrote:
> Marcus Clyne wrote:
>
>> I'm trying to create a shared object file calling GCC using execvp,
>> but am getting some errors.
>
> Does it work directly from the shell?
Yes No, though I'm not sure why.  The following results for readelf -h are:

(shell created)

ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              REL (Relocatable file)
  Machine:                           Advanced Micro Devices X86-64
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          1400 (bytes into file)
  Flags:                             0x0
  Size of this header:               64 (bytes)
  Size of program headers:           0 (bytes)
  Number of program headers:         0
  Size of section headers:           64 (bytes)
  Number of section headers:         13
  Section header string table index: 10

(execvp created)

ELF Header:                                                          
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00          
  Class:                             ELF64                          
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              REL (Relocatable file)
  Machine:                           Advanced Micro Devices X86-64
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          1384 (bytes into file)
  Flags:                             0x0
  Size of this header:               64 (bytes)
  Size of program headers:           0 (bytes)
  Number of program headers:         0
  Size of section headers:           64 (bytes)
  Number of section headers:         13
  Section header string table index: 10

>
>> This seems to go ok, then calling with the following options:
>> -------------------------
>> -fPIC -shared -o /tmp/simpl-so/objs/10.so \
> > /tmp/simpl-so/objs/10.o -lsimpl
>> -------------------------
>
> And what the 'manual' linking would tell? Does it succeed?
If you mean by calling gcc from the shell, yes, it does work.
>
>> COLLECT_GCC_OPTIONS='-v' '-shared' '-o' '/tmp/simpl-so/objs/10.so'
>> '-mtune=generic'
>>
>> libsimpl is compiled using fPIC too.
>
> And with the same '-mtune=generic' ?
Yes - I hadn't changed it, but I also set it to 'generic' explicitly,
and the new errors (which are different from the original errors) are
still the same - I put these in a separate post.
>
> -shared
>   Produce a shared object which can then be linked with other objects to
>   form an executable. Not all systems support this option. For
>   predictable results, you must also specify the same set of options
>   that were used to generate code (‘-fpic’, ‘-fPIC’, or model
>   suboptions) when you specify this option.
I'm actually creating so's that will be linked using dlopen etc - not
sure if this makes a difference or not.

In any case, it works ok when I use the shell but not when I use
execv(p) to call gcc.

Thanks,

Marcus.