time travel debugging with non RR tools (QEMU, ...)

[jeras]

Hi,

Midas support for reverse execution (buttons, ...) seems to be tightly integrated with rr specifically.

Would it be possible to use midas with a different tool providing record/replay functionality.
For example would it be possible to connect to the GDB stub interface in QEMU.

QEMU provides record/replay functionality
which is advertised over the GDB remote serial protocol
by answering with ReverseContinue+, ReverseStep+ to the qSupported packet.
rr seems to do the same.

I have seen somewhere mentioned a dedicated snapshot button, but I lost the page.
It would be usefull to be able to make a QEMU snapshot by pressing a button in the debugger (or with a script),
I still have to check if QEMU exposes such functionality over the GDB remote serial protocol (seems it does not, only through the monitor).
If it does not, I can write an issue asking for this to be added.

I am actually working on integrating a HDL simulator with a GDB stub.
For now I am using QEMU as a reference, since the functionality is similar to mine,
and since it is much easier to ask somebody to install QEMU than my tool.

The current list of functionality I am looking for is:

• reverse execution buttons,
• snapshot button (not really necessary, CLI is useful enough),
• detach/reattach button (the HDL simulator becomes unresponsive during blocking socket read, so I detach to get is responsive again),
• support for all watchpoint types (write read and access),
• maybe messages for record/replay specific events, like reaching the end/beginning of the record.