Hi all, I've been working on a platform-independent system for executables and shared libraries to expose functionality to debug, monitoring, and analysis tooling. It's called Infinity. I'm writing it to solve some problems GDB has, but these are likely problems LLDB has too so I'd like to make what I write suitable for you to use too.
The initial use case is to allow GDB to debug multithreaded inferiors without libthread_db, a requirement which causes problems with debugging inferiors in containers and makes it difficult to debug core files from one platform with a debugger on another (e.g. debugging an aarch64 core on your x86_64 workstation). If Infinity proves acceptable to the glibc community then it's likely this stuff will be added to glibc to allow debuggers to support dlmopen too, and I'm hoping the OpenMP community will get on board too (they are currently proposing another libthread_db-style interface). Rather than requiring a plugin library that the debugger loads, in Infinity debug functions are shipped as DWARF bytecode in the actual library they are for, so, e.g., the notes implementing what libthread_db.so currently implements live in libpthread.so. The idea is that the debugger keeps a track of the notes it finds in the executables and libraries it loads, and when complete sets arrive it enables that particular subsystem. So, when the notes needed to support multithreaded inferiors appear then thread debugging switches on. This works regardless of whether the notes came from a library (libpthread.so) or from the main executable (-static -pthread). What exists so far? * Enough notes for GDB to attach to a process (or load a core file) and do "info threads". * An LGPLv2.1 client library to process and execute those notes. The final plan is for GDB to directly call the client library functions, but to allow people to see how this all works I've put together a shim libthread_db.so that loads notes from the inferior and uses the client library to execute them. If you'd like to try this out there are instructions here: https://infinitynotes.org/wiki/First_Flight The code in the libthread_db shim is something like what would need adding to LLDB, minus the ELF parsing which LLDB presumably already handles. For gdbserver there will be some remote protocol changes; gdbserver does not parse ELF, so GDB will have to extract the notes and pass them over the wire somehow. I don't know if lldbserver handles ELF parsing or not, but if it doesn't I'd like to collaborate to make sure that the gdbserver remote protocol changes are suitable for lldbserver too so we're talking the same language. Infinity's mailing list is infin...@sourceware.org, so please subscribe if you're interested (by sending an empty message to infinity-subsribe@). Thanks, Gary -- https://infinitynotes.org/ _______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
