Re: [committed, PATCH] Always create dynsym section with dynamic sections

["H.J. Lu" <hjl.tools@gmail.com>]

On Sat, Apr 23, 2016 at 8:24 AM, Faraz Shahbazker
<faraz.shahbazker@imgtec.com> wrote:
> On 04/23/16 05:27, H.J. Lu wrote:
>> On Fri, Apr 22, 2016 at 7:31 PM, Faraz Shahbazker
>> <faraz.shahbazker@imgtec.com> wrote:
>>> On 04/22/16 19:05, H.J. Lu wrote:
>>>> On Fri, Apr 22, 2016 at 6:37 PM, Faraz Shahbazker
>>>> <faraz.shahbazker@imgtec.com> wrote:
>>>>> On 04/22/16 16:24, H.J. Lu wrote:
>>>>>> On Fri, Apr 22, 2016 at 2:49 PM, Faraz Shahbazker
>>>>>> <Faraz.Shahbazker@imgtec.com> wrote:
>>>>>>> On 04/22/2016 12:28 PM, H.J. Lu wrote:
>>>>>>>> On Fri, Apr 22, 2016 at 11:55 AM, Faraz Shahbazker
>>>>>>>>> + if (dynsymcount != 0 || elf_hash_table (info)->dynamic_sections_created)
>>>>>>>>> +     ++dynsymcount;
>>>>>>>>
>>>>>>>> Are you saying dynamic_sections_created is 0 for MIPS here
>>>>>>>> and will become 1 later?
>>>>>>>
>>>>>>> No, it will remain 0. The link is static, but the hash_table is still used to
>>>>>>> record global symbols that have GOT relocations against them. Ofc, this
>>>>>>> hash_table does not result in creation of a dynsym section, because well,
>>>>>>> dynamic_sections_created is 0.
>>>>>>>
>>>>>>> Check the list of callers to bfd_elf_link_record_dynamic_symbol(), a number of
>>>>>>> architectures use the link_hash_table in situations where it is not clear whether it is
>>>>>>> being used to track dynamic symbols for a dynamic executable, as it is for x86.
>>>>>>>
>>>>>>
>>>>>> So MIPS doesn't have dynamic symbols in this case.  It just borrows
>>>>>> dynsymcount for different purpose.  Is this correct?
>>>>>
>>>>> Not quite! MIPS is expecting dynsymcount to count the number of symbols
>>>>> that would have gone in to the .dynsym, even for a static executable. That way
>>>>> parts of the arch-specific code can remain agnostic to the static/dynamic nature
>>>>> of the link. It may not be used exactly as documented, but its not being used
>>>>> for what one would call a different purpose.
>>>>>
>>>>> All we need is for handling of dynsymcount when renumbering to be consistent with
>>>>> its initialization. If the initial increment for a NULL symbol was not gated by
>>>>> dynamic_sections_created, then the increment when renumbering should also not.
>>>>> If the increment when renumbering has to be gated by dynamic_sections_created,
>>>>> then the initial increment must also be so.
>>>>
>>>> From what you are saying, shouldn't dynsymcount be incremented
>>>> unconditionally?
>>> No. Always, when the table is non-empty + whatever else you need.
>>>
>>
>> You said dynsym should be treated treated the same for static and
>> dynamic executables.   dynsymcount is number of dynsym + 1 in
>> dynamic executable.  Why isn't it true for static executable?
>
> It is, or at least used to be, before this patch. It still is for both,
> before renumbering. But now the +1 only happens for dynamic executables
> when renumbering.

Then what is wrong to always +1 for both dynamic and static
executables?

-- 
H.J.