Re: gdb-7.12 powerpc-rtems4.12-gdb does not build on FreeBSD.

[Pedro Alves <palves@redhat.com>]

On 11/24/2016 02:46 AM, John Baldwin wrote:
> On Thursday, November 24, 2016 11:30:11 AM Chris Johns wrote:
>> On 24/11/2016 11:15, John Baldwin wrote:
>>> On Thursday, November 24, 2016 10:16:10 AM Chris Johns wrote:
>>>> On 23/11/2016 10:38, Chris Johns wrote:
>>>>> Hi,
>>>>>
>>>>> I am getting:
>>>>>
>>>>> ../sim/ppc/libsim.a(sim_calls.o): In function `sim_io_printf_filtered':
>>>>> ../../../gdb-7.12/sim/ppc/sim_calls.c:(.text+0x17c): undefined reference
>>>>> to `error'
>>>>> ../sim/ppc/libsim.a(sim_calls.o): In function `sim_load':
>>>>> ../../../gdb-7.12/sim/ppc/sim_calls.c:(.text+0x291): undefined reference
>>>>> to `error'
>>>>> ../../../gdb-7.12/sim/ppc/sim_calls.c:(.text+0x31d): undefined reference
>>>>> to `error'
>>>>> ../../../gdb-7.12/sim/ppc/sim_calls.c:(.text+0x357): undefined reference
>>>>> to `error'
>>>>> ../sim/ppc/libsim.a(sim_calls.o): In function `sim_create_inferior':
>>>>> ../../../gdb-7.12/sim/ppc/sim_calls.c:(.text+0x53e): undefined reference
>>>>> to `error'
>>>>>
>>>>> and errors.o has the following symbols:
>>>>>
>>>>>    nm
>>>>> build/powerpc-rtems4.12-gdb-7.12-x86_64-freebsd10.3-1/build/gdb/errors.o
>>>>> 0000000000000120 T _Z14internal_errorPKciS0_z
>>>>>                    U _Z15internal_verrorPKciS0_P13__va_list_tag
>>>>> 00000000000001a0 T _Z16internal_warningPKciS0_z
>>>>>                    U _Z17internal_vwarningPKciS0_P13__va_list_tag
>>>>> 0000000000000090 T _Z5errorPKcz
>>>>>                    U _Z6verrorPKcP13__va_list_tag
>>>>> 0000000000000000 T _Z7warningPKcz
>>>>>                    U _Z8vwarningPKcP13__va_list_tag
>>>>>
>>>>> Is there a C++/C thing happening here between the PCC simulator and GDB?
>>>>>
>>>>
>>>> A follow up. It looks like GDB is being built by cc which is clang on
>>>> FreeBSD. I am told by Joel this gdb target builds on Linux.
>>>>
>>>> I do not know what the extern binding is for gdb, C or C++?
>>>
>>> clang vs gcc shouldn't really break this.
>>
>> Yes I agree.
>>
>>> What undefined symbols do you see
>>> in the nm of sim_calls.o?
>>
>> The symbol is `error` and in my original post I showed the output of nm 
>> for the errors.o object file and `error` symbol is mangled. One thing 
>> that confuses me is only this symbol is being reported and there must be 
>> other calls to gdb.
> 
> FYI, I reproduced this with gdb's master branch using
> "configure --target  powerpc-rtems4.12-elf" (albeit on FreeBSD 11, though
> I have gcc48 installed as /usr/local/bin/gcc and configure found that and
> used it instead of cc).  The raw symbol in sim_calls.o is indeed plain C:
> 
> % nm sim/ppc/sim_calls.o  | grep error
>                  U bfd_get_error
>                  U error
> 0000000000000a20 T sim_io_error
> 
> Compiling gdb as C isn't an option on 'master', so it will need a different
> fix.  Probably the sims need to be built as C++ now.

The PPC sim shouldn't be calling GDB's "error" directly.  If it does,
then that's should be fixed.  There's an "error" method in the
host_callback structure (filled in by GDB) that should be used instead.

Thanks,
Pedro Alves