musl - Re: [RFC PATCH] Fix __libc_start_main prototype in [r]crt1.c to match the caller

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Message-ID: <20181121161518.d2ouey2zovz3gyrx@core.my.home>
Date: Wed, 21 Nov 2018 17:15:18 +0100
From: Ondřej Jirman <megous@...ous.com>
To: musl@...ts.openwall.com
Subject: Re: [RFC PATCH] Fix __libc_start_main prototype in [r]crt1.c
 to match the caller

On Wed, Nov 21, 2018 at 04:22:17PM +0100, Szabolcs Nagy wrote:
> * Szabolcs Nagy <nsz@...t70.net> [2018-11-21 16:09:04 +0100]:
> 
> > * megous@...ous.com <megous@...ous.com> [2018-11-21 15:51:50 +0100]:
> > > From: Ondrej Jirman <megous@...ous.com>
> > > 
> > > __libc_start_main function is not using the last three arguments.
> > > GCC in LTO mode complains about mismatch.
> > 
> > fix it in the other way then.
> > 
> > > -	__libc_start_main(main, argc, argv, _init, _fini, 0);
> > > +	__libc_start_main(main, argc, argv);
> > 
> > you just completely broke everything there didnt you?
> > 
> 
> sorry the _init, _fini there is only needed for glibc compat
> (i.e. executable linked with musl crt1.o, but using glibc
> to run it, which should not be a common use case)

I had a hunch that there was some reason outside of musl for these arguments,
therefore just the RFC. I guess, it's better to ignore the patch then.

I just saw a difference of prototypes, so I sent the patch.

> > how will the _init/_fini code of executables with
> > DT_INIT, DT_FINI dynamic tags run?
> > 
> > i think gcc still havent fixed weak object symbol alias
> > bugs with lto so e.g. you will get incorrect environ if
> > you lto link the libc.
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69271
> 
> these lto issues still apply.

I'm attempting a static build, for which this issue should not apply, AFAIK.

Though, I'm trying on mips, and it leads to GOT related error. So LTO of musl+my
code doesn't work anyway, because ld fails. I'll try with some other target just
to see if I can get something that works, without the limitations of mips arch.

regards,
  o.

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