[gentoo-soc] Weekly Report: Porting relibc Relibc

[gentoo-soc] Weekly Report: Porting relibc Relibc

[Ahmed Soliman]

Hello,

I wrote a blog post about my work during this week for gsoc, you can
find it as well as the pull request with the patches that are
described in the post

Post:
https://oddcoder.com/What-if-debugger-couldnt-help/

Pull request:
https://gitlab.redox-os.org/redox-os/relibc/-/merge_requests/290

Demo:
https://asciinema.org/a/hcjaz8VVvBP550Pi5YWW64FOJ

Thanks
Ahmed.

Re: [gentoo-soc] Weekly Report: Porting relibc Relibc

[Benda Xu]

Hi Ahmed,

Ahmed Soliman <ahmedsoliman0x666@gmail.com> writes:

> I wrote a blog post about my work during this week for gsoc, you can
> find it as well as the pull request with the patches that are
> described in the post
>
> Post:
> https://oddcoder.com/What-if-debugger-couldnt-help/
>
> Pull request:
> https://gitlab.redox-os.org/redox-os/relibc/-/merge_requests/290
>
> Demo:
> https://asciinema.org/a/hcjaz8VVvBP550Pi5YWW64FOJ

Please give more details about what you have done to the mailing list
besides the blog post link.

Benda

Re: [gentoo-soc] Weekly Report: Porting relibc Relibc

[Luca Barbato]

On 06/07/2020 00:06, Ahmed Soliman wrote:
> Hello,
> 

Hi, when gdb is having problems, rr might help you. I guess you know it 
already but just in case :)

Thank you for your nice blogpost.

lu

Re: [gentoo-soc] Weekly Report: Porting relibc Relibc

[Ahmed Soliman]

Hi,

I will try to add a short description here, However, the post should
be describing most of the technical issues that I kept track of.

So i was working on compiling gcc under gentoo and having it linked
against relibc. there were plugins for LTO that are part of gcc but
used via ld. The plugins are shared object styles, so in order for
them to work I needed a working dlopen, dlclose and dlsym. which was
not yet implemented in relibc. I implemented all 3, There were
challenges where relibc and rust stdlib are not referentially
transparent. And that caused problems where there was a relibc copy
statically linked against ld.so for internal use and one that is
dynamically linked against an arbitrary a.out for external use and
although both are the same binary wise, they cannot be used
interchangeably for some reason. It was hard figuring out.

That is also why I mentioned that gdb wasn't useful, not because it
wasn't working (in fact I added support for it in a previous patch
set) but because of the nature of the bug I faced, It was not
something that one can pinpoint quickly when using a debugger.

Thanks,
Ahmed.

On Mon, 6 Jul 2020 at 08:22, Luca Barbato <lu_zero@gentoo.org> wrote:
>
> On 06/07/2020 00:06, Ahmed Soliman wrote:
> > Hello,
> >
>
> Hi, when gdb is having problems, rr might help you. I guess you know it
> already but just in case :)
>
> Thank you for your nice blogpost.
>
> lu
>
>

Re: [gentoo-soc] Weekly Report: Porting relibc Relibc

[Luca Barbato]

On 06/07/2020 09:45, Ahmed Soliman wrote:
> 
> That is also why I mentioned that gdb wasn't useful, not because it
> wasn't working (in fact I added support for it in a previous patch
> set) but because of the nature of the bug I faced, It was not
> something that one can pinpoint quickly when using a debugger.

Thus why I suggested using rr, it usually helps when tracking issues 
hard to pinpoint using the normal gdb. :)

lu

Re: [gentoo-soc] Weekly Report: Porting relibc Relibc

[Ahmed Soliman]

Oh I see thank you, for some reason I thought rr might be the nickname
of someone on IRC who might help with issues arising in GDB.

Thanks for pointing out the tool!
Ahmed.

On Mon, 6 Jul 2020 at 10:55, Luca Barbato <lu_zero@gentoo.org> wrote:
>
> On 06/07/2020 09:45, Ahmed Soliman wrote:
> >
> > That is also why I mentioned that gdb wasn't useful, not because it
> > wasn't working (in fact I added support for it in a previous patch
> > set) but because of the nature of the bug I faced, It was not
> > something that one can pinpoint quickly when using a debugger.
>
> Thus why I suggested using rr, it usually helps when tracking issues
> hard to pinpoint using the normal gdb. :)
>
> lu
>