Debugging with GDB: Registering Code

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### 29.2 Registering Code

To register code with GDB, the JIT should follow this protocol:

- Generate an object file in memory with symbols and other desired debug information. The file must include the virtual addresses of the sections.
- Create a code entry for the file, which gives the start and size of the symbol file.
- Add it to the linked list in the JIT descriptor.
- Point the relevant_entry field of the descriptor at the entry.
- Set `action_flag` to `JIT_REGISTER` and call `__jit_debug_register_code`.

When GDB is attached and the breakpoint fires, GDB uses the `relevant_entry` pointer so it doesn’t have to walk the list looking for new code. However, the linked list must still be maintained in order to allow GDB to attach to a running process and still find the symbol files.