Error early if the box VM would overcommit the host memory

[kageurufu]

I was testing how boxed works on low memory systems, and it will readily overcommit memory and get quickly reaped by the OoM killer.

It would be useful to add a quick check that the requested box memory is larger than the free/available memory instead of just crashing a host.

Came here from rockstor/rockstor-installer#73 btw

[schaefi]

Hi @kageurufu. I was looking through the open boxbuild issues and came across this one. Sorry for the very late response but the internet never forgets :)

I was also testing on low memory systems (rPI 4G arm64) with the default (8G) setting for the box VM. In my case it immediately stops at the qemu call with an error message that not enough memory is available to associated with the VM. I played with reduced memory up to the max available one on the machine. I did not observe OoM kills from the host kernel though.

As such I'm wondering for a reproducer of this condition and couldn't it also just be an issue with qemu on this host ?

Thanks