Registering Code (Debugging with GDB)

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30.2 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.