run --rootfs mounts the rootfs as tmpfs

[acromc]

Hi all, I want to use podman run with rootfs dirs directly instead of Docker/OCI images via the --rootfs option. However I noticed that the rootfs is mounted as a tmpfs (with a size of 2.1 GB if the rootfs dir size is smaller than 2.1 GB and barely the tmpfs size if the dir size is larger than 2.1GB). I also noticed that containerd does the same behavior when using the rootfs option via nerdctl. Can I understand why the rootfs is mounted as a tmpfs and not a typical bind mount? also is there any option to control the size of tmpfs of the rootfs if it has to be a tmpfs mount? I know podman can optionally use overlayfs but I don't want to use overlay since I want the changes to be directly done to the rootfs.
I simply hope there is an option that makes podman run the rootfs directly just like crun or runc.

[acromc]

Excuse my ignorance. This has nothing to do with podman or containerd. It looks like OCI runtimes mount rootfs dirs in the same type of their own filesystems. i.e. if the rootfs dir lies in a tmpfs it will be mounted as a tmpfs, if its a directory in ext4 it will be mounted as ext4 and so on.