I'm not sure if this list is complete

The following shows all additional options the XBian command line cmdline.txt respective boot.scr.txt for Cubox-i/Hummingboard offers:

• noresizesd disables the automatic SD resize to full capacity.
• partswap creates a separate swap partition instead of using a swap file.
• noswap disables the creation of a swap file with standard system scripts / tools. Because swap is handled with zram-swap package on xbian, this option tells the system to skip all tasks around swaps (activating, waiting to appear, deactivating during reboot/shutdown etc.)
• noconvertsd won't convert the EXT4 filesystem to BTRFS. Convertion will run only if rootfstype=btrfs is specified and actual filesystem is EXT4. The actual location of the root partition is not relevant. XBian will convert the USB stick or external hard drives it is booting from (if the actual filesystem is still EXT4 and BTRFS is specified in cmdline.txt).
• root= this parameter can not only hold device path's but also partition labels root=LABEL=xbian-root-btrfs, UUID's root=UUID=12345-0123-10234 or PARTUUID's root=PARTUUID=abcdefab-02
• rootflags=subvol=root/@,autodefrag,compress=lz4 specifies additional mount options for the root partition.
• rootwait=10 specifies the maximum number of seconds the initramfs should wait until a root device has become available. Especially handy for booting from external USB or HDD devices.
• splash shows the XBian splash.
• debug shows as much debug information as possible (overrides the loglevel, console, and quiet parameter).
• rescue will drop you to a rescue shell just before mounting rootfs to /rootfs. It is possible to continue with booting after typing exit).
• rescue_early will drop you to a rescue shell early in the initramfs process. It is possible to continue with booting after typing exit.
• rescue_late will drop you to a rescue shell at the end in the initramfs process (before switching to root). It's possible to continue with booting after typing exit.
• telnet will start a telnet session at boot time. This can be handy to fix your system before SSH has started. Telnet will be stopped when SSH has been started.
• vnc will start VNC server at boot time if VNC stuff has been included in initramfs. For more information please read /etc/default/xbian-initramfs
• modules-load=module1=param=value,module2… this parameter allows loading kernel modules without the need of adding them to /etc/modules file or adding a conf file into one of the supported modules-load.d/ folders. Format is as follows (modules are separated by comma, params by colon): modules-load=moduleA[=paramA1=valueA1[:parmA2=valueA2][:…]]][,moduleB[=paramB1=valueB1], for example modules-load=bridge,em28xx=disable_ir=1:i2c_scan=100:core_debug=1:reg_debug=0

A ad-hoc rescue mode exists since version Beta 1. This add the possibility to trigger a rescue-like shell by holding down the shift key during boot with an USB attached keyboard. This is possible even with splash as default parameter in cmdline.txt. The shell console is restored during this rescue mode. However, mod_scsi.scan=sync is recommended as opposite to the default mod_scsi.scan=async, because the initramfs phase finish faster then USB devices appear to the system.

You can use init=/bin/bash instead of running init=/sbin/init. The default init is used to start loading services and mount filesystems. When you use init=/bin/bash, bash will get the first pid, the rootfs will be at /, and the /proc, /run, /sys, /dev will be mounted and populated. All console applications should start normally. However, typing exit to continue booting no longer works, but if you want to continue with the normal boot process, you can type exec /sbin/init.