GDB 18.1 brings non-stop debugging to Windows and drops stabs and CTF
Serguey Asael Shinder2 min readVersion 18.1 of GDB, the GNU debugger, has been announced by Andrew Burgess on the gdb-announce list. The largest block of changes is for Windows. The native Windows target now supports non-stop mode on Windows 10 and later, set scheduler-locking on finally works there, native thread-local storage variables are supported, and on Windows Terminal GDB can use 24-bit colour and UTF-8 output when the console code page is 65001. File names are now printed consistently with forward slashes instead of mixed separators.
Everyday use gets a handful of small but welcome commands. save history, save skip and save user write the command history, the current skips and user-defined commands to a file. A new local-environment family of commands controls the environment of processes GDB itself starts through shell and pipe, separate from the debuggee's environment. info locals now marks variables that shadow, or are shadowed by, another variable, and a new "essential" help class lists a minimal set of commands for new users. Inferior arguments can now contain quoted newlines, and a --no-escape-args option passes arguments without escaping shell characters.
The Python API gains a gdb.Corefile class describing a loaded core file and its mapped files, new event registries for context and core-file changes, and styling support in disassembly output.
What it means
The removals deserve as much attention as the additions. GDB 18.1 drops support for the stabs and mdebug debug formats and the dbx binary format, removes Common Trace Format output entirely, stops reading .gdb_index sections older than version 7 and DWARF package files of version 1, and changes the format of saved execution records so older ones no longer load. AIX 7.1 is no longer supported. Anyone debugging old toolchains, archived traces or long-lived build artefacts should check before upgrading, because these are exactly the files that sit untouched until someone needs them during an incident.
The .gdb_index change has a practical instruction attached: GDB now adds all type symbols to the index, fixing cases where types could not be found, and the release notes say existing indexes should be regenerated. Teams that build indexes into release artefacts will get the fix only after rebuilding them.
For Windows developers, non-stop mode is the headline. It lets some threads keep running while others are stopped, which is how multi-threaded servers are normally debugged on Linux; until now Windows users had to stop the whole process at every breakpoint.