Date: Thu, 28 May 2015 13:45:15 +0200 From: Szabolcs Nagy <nsz@...t70.net> To: musl@...ts.openwall.com Subject: Re: Progress since 1.1.9 * Rich Felker <dalias@...c.org> [2015-05-27 19:13:08 -0400]: > The one roadmap item I don't have any progress on is what to do with > the libgcc_s symbol version mess, and I think we should probably just > hold off until the next release cycle for that now. in case anyone wonders about the issue: libgcc_s has a symbolic reference to an internal deprecated symbol with no default version on x86 (in gcc trunk). (so no @version only @@version which makes it invisible to musl and ld). the deprecated function is a constructor in libgcc_s that initializes an unused struct in libgcc_s. the only reason the symbol got versioned this way is because they want old binaries to work and remove the symbol from libgcc_s for new binaries, while still using the same symbol name in new binaries but with different abi behaviour: now it's only available in libgcc.a to fix their ifunc hack for multi-versioning. since it's a symbol internal to libgcc and the semantics of the symbol changed they could have just used a new name and left the old one alone (so old stuff is guaranteed to not break including musl and new binaries use the new symbol with new semantics). so i still think my proposed libgcc patch makes more sense than versioning: https://gcc.gnu.org/ml/gcc-patches/2015-05/msg00899.html gcc is unlikely to fix this, but this is a nonsense usecase (and there is no other known use of versioning that is broken with musl.. in theory other libs may deprecate symbols in a similar way while still keeping symbolic references to them, but such use was not yet observed). in musl-gcc it can be worked around by preloading a noop __cpu_indicator_init and in a musl based gcc it can be patched out.
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