Am 15.12.2011 14:18, schrieb Jan Kiszka:
On 2011-12-15 14:02, Stefan Hajnoczi wrote:
What is the status of QEMU's transition from HMP to the QMP interface?
My current understanding is that QEMU provides new HMP commands for humans, but HMP is being phased out as an API. Management tools should rely only on QMP for new commands. That would mean new HMP commands are not guaranteed to produce backwards-compatible output because tools are not supposed to parse the output.
On the libvirt side, new QEMU features should only be supported via the json monitor in the future (i.e. human monitor patches should not be sent/merged)? Existing HMP commands will still need the human monitor support in order to handle old QEMU versions gracefully, but I'm thinking about new commands only.
Does everyone agree on this? I think this is an important discussion if we want our management interface to get better and more consistent in the future.
To phase out the classic HMP implementation, we need an internal HMP-over-JSON wrapper (with tab expansion etc.) so that virtual console and gdbstub monitors continue to benefit from new commands. Those interfaces will stay for a long time, I'm sure.
I think we're not talking about dropping HMP here, only about how long to support it as a stable API for management tools. I believe that we have been in a transitional phase for long enough now that we can start changing the output format of HMP commands without considering it an API breakage. Kevin