In the short term, you can add swap to your VM, to give more resources without a reboot. This is only an interim workaround though, and will not be as fast as real ram.
In VMWare? No this is not possible. It's not the client OS stopping you, its your virtualisation platform.
It is "kind-of" possible in xcp-ng but only up to a specific number that you set before boot.
So a VM can be started with 2 CPUs and 2 GB ram, which can be increased provided you set the maximum numbers before boot. Eg:
- Maximum memory can be no more than 4x the boot memory.
- CPUs maximum is 32, and if the physical host has less, then the extra are faked which hurts performance
- Your OS has to support hot-add (most linux distros do)
And of course you need to run xcpng, not vmware.