In the brief installation documentation here:
For installation via the rpm file, it reads: "Except the traditional ISO files, we also package android-x86 files into a Linux package rpm. It allows Linux users to easily install the release into an existing Linux device with a standalone ext4 root partition."
But there is no explanation about how to do exactly that. If I follow the installation instructions and install the rpm file with the rpm or alien commands, by default it is installed to a directory called "android-9.0-rc1" in the system root directory. So how do I install it to a dedicated ext4 partition? I suppose that I could just create an ext4 partition and copy the contents of that directory to the partition, but then I would have to manually update grub2 accordingly, and I have to admit that I am not an expert at grub2. Anyway, having to do that defies the above description of it being done "easily".