SPBLinux 2.2 boot menu:

Syslinux (isolinux, extlinux) is used as bootloader
- all boot entries can be modified at boot time (tab key)
- the files menumain and menusub define the boot menu
  (if these template files are edited the command
  update_bootmenu has to be run inside SPBLinux)

Many properties of SPBLinux can be set at boot time
- by normal kernel boot parameters as described below
- by spblinux boot parameters which are loaded from
  - spbconf=...,par1=value1,par2=value2,par3=value3
    (spbconf is a kernel boot parameter)
  - configuration files spblinux/spbcfgX (X=0..9)
    if spbconf=...,cfgdevX,... is set
  - defaults are set in init6.gz (etc/spb.conf)
    (use command changeaddon your_path/init6.gz to edit
    these defaults; changeaddon is a command inside SPBLinux)
  - when SPBLinux is running /etc/spb.conf contains
    all parameters which are in currrent use (with usage info)

boot splash image: activated by
  vga=788 console=tty1 quiet (key F2 unhides the boot messages)

spbrootsize=M, spbaddonsize=N: size in MB of 2 fixed ramdisks used
for / and /usr (M,N=3,4,8,16,32,64; defaults: M=4, N=32)
(/home and /tmp use tmpfs and are not limited in size by M,N;
big addons use their own squashfs and are not limited by M,N)

spbrd=X initsqf=X: SPBLinux fast boot mode (X=0...9)
- in normal boot mode SPBLinux loads init6.gz and
  all addons in subdirectories given by addons:subdir=...
- at first boot in fast boot mode SPBLinux creates
  the two fastboot files in directory spblinux/ (X=0..9)
  - spbrootX (a ext2fs ramdisk image of /)
  - initsqfX (a readonly squashfs image of /usr)
  - write access to spblinux/ folder required at boot time
  - at least 256 MB RAM is needed to create the fastboot files
- in fast boot mode only spbrootX and initsqfX are loaded
  - /usr filesystem is compressed and readonly
  - the boot process is faster and less RAM is used

root=...: SPBLinux extends the syntax of this boot parameter
- root=ext3:/dev/sda1 forces filesystem type ext3
- root=tftp://1.2.3.4:/path loads SPBLinux from network
  (tftp, ftp, http, cifs, nfs, nbd, vboxsf; uses ramdisk with network files)
- if init6.gz is not found a shell prompt gets started