[libvirt] [Question] (python API) setMemoryParameters doesn't support flags CONFIG | LIVE

[Wangrui (K)]

Hi, all

when I use (python API) setMemoryParameters with flags= VIR_DOMAIN_AFFECT_CONFIG|VIR_DOMAIN_AFFECT_LIVE ,
an error occurs as follow: (libvirt 1.2.4)

libvirt:  error : flags 'affect live' and 'affect config' in virDomainGetMemoryParameters are mutually exclusive

I check the function libvirt_virDomainSetMemoryParameters in libvirt-override.c and find the code below:

Line 1204-1206:
     LIBVIRT_BEGIN_ALLOW_THREADS;
     i_retval = virDomainGetMemoryParameters(domain, NULL, &nparams, flags);
     LIBVIRT_END_ALLOW_THREADS;

Line 1220-1222:
    LIBVIRT_BEGIN_ALLOW_THREADS;
    i_retval = virDomainGetMemoryParameters(domain, params, &nparams, flags); 
    LIBVIRT_END_ALLOW_THREADS;

Function virDomainGetMemoryParameters doesn't support flags VIR_DOMAIN_AFFECT_CONFIG|VIR_DOMAIN_AFFECT_LIVE.
So the error above occurs.

The first call of virDomainGetMemoryParameters is to "cause @nparams on output to contain the number of parameters
supported by the hypervisor". And what's the role of the second call?

Maybe, so do other functions such as *libvirt_virDomainSetSchedulerParameters, *libvirt_virDomainSetBlkioParameters
In commit 56cec18d761a1f99862c43811de60380c65881e6.

IMHO, an example flag (such as VIR_DOMAIN_AFFECT_CONFIG) can be used in virDomainGetMemoryParameters  
just to get something from hypervisor rather than @flags which is a parameter of setMemoryParameters .