In initrd, init program is needed or not?

Hi, all
I am a newbie in ramdisk, I could not find the answers of the following questions in the previous maillists.

There is a program, called init, in some ramdisk.image.gz. however in SIMPLE-ramdisk.image.gz, I did not find it.
I could not understand what the init programe does?

BTW, if I want to access /proc/... , what files should I add in ramdisk. Should I add a program called MOUNT in /bin? who exec rc and fstab script , shell(bash , ash) or kernel?
Thank you in advance.


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