To be clear I included the patch in this series only because:
- I couldn't figure out any way to send a serial break to the ARM Foundation Model making it impossible for me to provoke SysRq actions from interrupt context,
Agreed, there's no direct way to do it (annoyingly).
Arguably that's a deficiency in the model, though that's not much help to you right now.
If it isn't affecting real hardware and it's just for a flawed model then hack a check for a suitable symbol into the specific patches for the model and its serial driver and claim it was a break - don't dump it into the mainstream.
There are some "conventional" escapes platforms have used (ctrl and symbols for example such as ctrl-^) which are less likely to cause conflicts than sequences. Nevetheless its not something you want anywhere mainstream if you can avoid it because those symbols could be sent over a remote management modem or similar.
They may be better if it does need to end up in the core kernel.
Alan