Re: [musl] ld-musl-* and empty .eh_frame

[Michael Forney <mforney@mforney.org>]

On 2021-03-05, Fangrui Song <i@maskray.me> wrote:
> The empty .eh_frame is suspicious, though. There may be two problems:
>
> 1. Why do you have an empty .eh_frame in an object file

There is no .eh_frame in any of the object files involved (neither t.o
or crt*.o), just in the final executable. It seems that GNU ld creates
a .eh_frame section unless you pass --no-ld-generated-unwind-info.

> 2. Why does ld.bfd create empty .eh_frame in that case (I have tried
>    simple examples like  `.section .eh_frame,"a"` and I cannot reproduce
>    the empty output .eh_frame)
>
> If you don't share the other files, it is difficult to locate the
> problem.

Which files are you interested in? The recipe I showed earlier should
be sufficient to reproduce the issue. You can use the standard alpine
linux toolchain (using /usr/lib instead of /lib for the paths to the
crt*.o files). With a musl.cc toolchain, you'll need to pass -z
separate-code to get the empty PT_LOAD segment, but the empty
.eh_frame is there either way.