The answer is simple:
It is not supported.

What do you need it for in GDB?
Writing custom DMI sequences should be only necessary for custom chip bringup, where InitTarget() in a script is the right place for.

For what do you need it after all the target connect etc. has already happened and GDB connected to the core?

If I have a specific use-case, I may be able to justify allocating the dev time for adding support in GDB Server, at the next team meeting.


BR
Alex

Hello Alex,

I am mmahdi's colleague.

We have a specific debugging case in our chip where we have the chip in an unrecoverable state (normal halt command won't work) and we need to send a command to for example force the halting of the cpu, I am doing this by writing a custom dmi register since the system is not yet halted and the CSR registers cannot be written yet, do you have a better idea in mind that may be already supported ?

Is there no way of sending any kind of custom instructions to the debug module ?

As GDB Server already tries to halt the core at startup of GDB Server, a monitor command would be too late.
As GDB as one of the first things requests the CPU registers, the core must be halted at the time GDB connects to GDB Server.

I recommend to use a script file with an InitTarget() function and do the DMI accesses there.