Re: [RFC PATCH 0/9] Initial support for machine creation via QMP

[Paolo Bonzini]

On 14/05/21 14:48, Mirela Grujic wrote:
> With our approach, transitioning to the QMP configuration suppose to 
> happen gradually, i.e. we still specify some configuration options via 
> command line. For your approach to be applicable to our use case we 
> would at least need a QMP equivalent for the following:
>
> qemu-system-riscv64 \
>      -M sifive_dt \
>      -cpu 
> rv64,i=true,g=false,m=true,a=true,f=true,d=true,c=true,s=false,u=false,x-b=true,pmp=true,mmu=false,num-pmp-regions=8 
> \
>      -smp 1 \
>      -device ...
>
> AFAIU from the materials you shared, we would need to add -cpu and 
> -device, but I don't see any reason why we wouldn't do this.

-cpu is indeed the big one that I had not looked at so far, while 
-device should be mostly covered by the existing device_add command.

One possibility for -cpu is to make it an argument of machine-set too. 
For example the above would be

{ 'execute': 'machine-set', arguments: {
    'type': 'sifive_dt',
    'smp': { 'cpus': 1 },
    'cpu': { 'model': 'rv64', 'i': true, 'g': false, ... }
}

> Ok, please let me know once you test, then I would run your code and
> play with it to better understand what needs to be done. Then I might
> come back with a couple of questions, so that we align on the TODOs. Is
> that ok with you?

Yes, of course.  I pushed something that at least compiles and passes a 
basic smoke test.

> Btw, when (in which version) did you plan to integrate the
> qemu-qmp-* support? I guess once machine-set/accel-set is implemented,  > but 
> maybe I'm wrong...

Well, the right answer is "when somebody needs it".  The things that I 
was mostly interested in (e.g. compound properties for machines, such as 
smp in the example above) were all enablers for qemu-qmp-* but I was not 
really interested in the new binaries.  I did the qemu-qmp-* patches 
mostly to validate that the 5.2/6.0 refactoring of preconfig was going 
in the right direction.

However, if there is indeed somebody that needs it I'll contribute where 
our interests overlap.  In particular I can take care of converting the 
command line options to properties.

Paolo