Automating Qemu and GDB together

[R. Diez]

Hi all:

I want to press a key and have my editor automatically launch Qemu and GDB. Like you do from within an IDE when writing PC software. How do I 
synchronise Qemu and GDB?

In case the question is not clear enough, here are the steps:

1) Start Qemu.
2) Wait until Qemu is ready to accept a GDB connection.
3) Start GDB in a new window.

The problem is step (2). I can launch Qemu in the background, pause for some time, and then launch GDB. However, if I make the pause too short, GDB 
will fail to connect, and if I make the pause too long, I will waste the user's time.

Besides, depending on the current system load, Qemu will sometimes need a 
longer time to start. For example, the first time, when the disk cache is cold.

I had a similar issue with OpenOCD and GDB. But OpenOCD accepts scripting commands, so I told it to write to a FIFO after initialising. The top-level 
script just needs to wait on the FIFO.

Alas, I have not seen a way to do that with Qemu yet. Can I somehow tell Qemu to run a command when the virtual machine is ready to accept a GDB 
connection?

Thanks in advance,
  rdiez