Fedora 38 LLVM vs Team Fortress 2 (TF2)

F38 just released and seeing a bunch of people complain that TF2 dies on AMD or other platforms when lavapipe is installed. Who's at fault? I've no real idea. How to fix it? I've no real idea.

What's happening?

AMD OpenGL drivers use LLVM as the backend compiler. Fedora 38 updated to LLVM 16. LLVM 16 is built with c++17 by default. C++17 introduces new "operator new/delete" interfaces[1].

TF2 ships with it's own libtcmalloc_minimal.so implementation, tcmalloc expects to replace all the new/delete interfaces, but the version in TF2 must not support or had incorrect support for the new align interfaces.

What happens is when TF2 probes OpenGL and LLVM is loaded, when DenseMap initializes, one "new" path fails to go into tcmalloc, but the "delete" path does, and this causes tcmalloc to explode with

"src/tcmalloc.cc:278] Attempt to free invalid pointer"

Fixing it?

I'll talk to Valve and see if we can work out something, LLVM 16 doesn't seem to support building with C++14 anymore. I'm not sure if static linking libstdc++ into LLVM might avoid the tcmalloc overrides, it might not also be acceptable to the wider Fedora community.

[1] https://www.cppstories.com/2019/08/newnew-align/

Comments

  1. Nicholas23 April 2023 at 21:47

    I have a little LD_PRELOAD stub that fixes similar problems in Battleblock Theater, which no doubt stopped working because I didn't bother with any of the aligned functions.

    ReplyDelete
  2. Nicholas23 April 2023 at 21:50

    The real fix is of course to lean on glibc to implement two-level name lookup like Windows/macOS/Solaris.

    ReplyDelete
  3. Jonathan @ jadbox.com24 April 2023 at 07:45

    Thank you for coordinating a fix for tf2 for fedora 38!

    ReplyDelete

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