[libvirt] Why not support additional machine args in XML such as max-ram-below-4g?

[Michal Privoznik]

On 08/21/2017 01:04 PM, Wuzongyong (Euler Dept) wrote:
> Since qemu support the arg -machine like that:
> -machine [type=]name[,prop[=value][,...]]
> So I'm inquisitive about why libvirt doesn't support specify the prop in xml ?

Usually libvirt features are request driven. In other words you seem to
be the first to need this property exposed. And in generic case, it's
questionable which properties should libvirt expose, and in what detail.
Whether we want libvirt to be just XML -> cmd line compiler, or we want
it to chose some sensible defaults and do something on the top of cmd
line translation.

> So I can specify the qemu machine args  like -max-raw-below-4g in xml, well, I mean not by specifying the -qemu-command-line in xml.

Nope. It is not implemented yet. But if you want, you can post patches.
BTW: it looks like the name changed from --max-ram-below-4g to
--below-4g-mem-size.

Michal