How to add bin files into initrd with mkinitrd

I customed initrd myself, i know add libs at /ect/sysconfig/kernel, then mkinitrd you can add needed lib, but init script in the initrd, i want to execute some program, how to add bin files into initrd with mkinitrd, and then i can used it in init script in the initrd. i know it can be added by manual.

maybe mkinitrd script hadn’t this function, so i added it manual, i added some in initrd. at /boot/, added iscsiadm and iscsid at /sbin/, added some libraries. cpio my own initrd, sync to iscsi storage, now i can startup SUSE ,but during boot ,at grub, i type:
grub>root (hd0,0)
grub>kernel /boot/vmlinuz ro root=LABEL=/
grub>kernel /boot/vmlinuz ro root=/dev/sda1
why, at RHEL or Cenos, to enhance stabilization, usually using like root=LABEL=

Don’t know if this is the place for your questions. AFAICS you changed the complete system. Therefore anything I can say would be a wild guess.

I know how to add modules to initrd using mkinitrd (option in /etc/modprobe.conf), i wonder if i want add some execute file or script to init script in initrd, can i also use mkinitrd? just like ,install suse with iscsi storage ,config advance storage and iscsi target, then install it.when you cpio the initrd-uname -r, you can see something different from local install in init script, like,
/bin/iscsistart -t targetname -g 1, how it added? mkinitrd?