Whether are some partitions mounted during the process of the cboot start?

Whether or not are some partitions mounted during the process of the cboot start?
I did not find the function of rootfs-mounted, can you show me where is the function?

Cboot has access to partitions, but does not mount them. They are accessed as binary data. Only the rootfs actually has a filesystem, and this is not truly mounted until the Linux kernel is loaded.