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TLS data/BSS alignment

Sebastian Huber sebastian.huber@embedded-brains.de
Mon Mar 23 12:54:08 GMT 2020 
On 23/03/2020 13:52, Nick Clifton wrote:

> Hi Sebastian,
>
>> Thanks for the hint. I found this code also, but I didn't understand how the different output sections in the ELF file are generated. I guess I have to dig a bit deeper.
> Alright, how about this from bfd/elflink.c:
>
> struct bfd_section *
> _bfd_elf_tls_setup (bfd *obfd, struct bfd_link_info *info)
> {
>    struct bfd_section *sec, *tls;
>    unsigned int align = 0;
>
>    for (sec = obfd->sections; sec != NULL; sec = sec->next)
>      if ((sec->flags & SEC_THREAD_LOCAL) != 0)
>        break;
>    tls = sec;
>
>    for (; sec != NULL && (sec->flags & SEC_THREAD_LOCAL) != 0; sec = sec->next)
>      if (sec->alignment_power > align)
>        align = sec->alignment_power;
>
>    elf_hash_table (info)->tls_sec = tls;
>
>    /* Ensure the alignment of the first section is the largest alignment,
>       so that the tls segment starts aligned.  */
>    if (tls != NULL)
>      tls->alignment_power = align;
>
>    return tls;
> }
Oh, great. Thanks, I focused on the wrong directory (ld instead of bfd).
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