Gdb core file support#17
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derekparker
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Apr 29, 2026
GDB's DAP implementation does not support core files via the launch
request. When the MCP server sent a launch request with a coreFile
argument, GDB ignored coreFile and ran the program from scratch,
resulting in a hang followed by session termination.
Upstream GDB handles core files via the attach request with a coreFile
argument, this has been added with GDB commit:
commit 0a481bb9a6d49591a7f21b132ff63a96704bce97
Date: Mon Mar 23 22:25:17 2026 +0000
gdb/dap: add support for opening core files
which is merged to GDB's master branch, and should be in the GDB 18
release later this year (2026). The approach taken by GDB is
consistent with how lldb-dap also handles core files. This commit
updates the server to make use of this new GDB functionality, after
which basic core file debugging now works as expected.
Delve continues to use launch requests with debug mode "core", and
should see no change after this commit.
A new CoreRequestType() method on the DebuggerBackend interface lets
each backend declare which DAP request type to use for core dump
debugging. The "core" debug mode uses this to create an appropriate
request type.
The only problem with this approach is that it requires building top
of tree GDB in order to test it.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
GDB can auto-detect the executable from a core file, so the path parameter is no longer required when using GDB in core mode. Delve still requires the path as it cannot perform this auto-detection. The gdbBackend.CoreArgs() method now omits the "program" field from the DAP attach request when no path is specified, letting GDB resolve it from the core file metadata. Adds TestGDBCoreDumpWithoutPath to verify path-less core debugging works alongside the existing TestGDBCoreDump with-path test. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Two changes to improve core file debugging using GDB.
path, instead allowing GDB to auto-detect it. I don't know if the delve debugger supports this, so for now I've leftpathas required when using delve for core file debug. I've also updated the docs in this commit, which in a few places meant adding text describing core file debug as it was otherwise missing.