How does Splashy work?

First of all your PC boots using a bootloader such as grub or lilo.

The bootloader then loads and runs a kernel and possibly an initrd.

1. The initrd is uncompressed into a ramdisk (ExamineInitrdContents) and starts to run the init command (a shell script).
   1. This creates directories in the ramdisk and does some temporary RAM filesystem setup.
   2. Then it runs udev (etc/udev/udev.conf) and sets up some script functions (scripts/functions) for the init scripts.
2. init then looks at the kernel command line options and processes them (eg nfsroot, ro, resume, quiet, panic, break=breakpoint etc)
3. init has several 'hook' points where it runs externally provided scripts (on Debian):
   1. init-bottom init-premount init-top local local-bottom local-premount local-top
4. init begins to run the first of these; the 'top' ones in scripts/init-top/… And that's where Splashy gets in on the act.
   1. There are 2 scripts: framebuffer and splashy
   2. There are no dependencies specified so init runs them in alphabetic order:
   3. framebuffer is provided by initramfs-tools and processes the video= and modprobes the specified framebuffer device.
   4. There is a slight problem that if it sees 'splash*' on the kernel line then it assumes usplash and sets the framebuffer to use the vga16fb module. For this reason, the video= or vga= option must come *after* the Splashy option on the kernel command line.
   5. The Splashy script is quite basic and simply looks for 'splash*' and 'single' on the command line, exiting for single user mode or if Splashy is not wanted.
   6. If it continues than it is hardcoded to modprobe both fbcon and vesafb. (ugh - I use neofb so need to hack this file!)
   7. Finally splashy is started in boot mode where it paints the splash screen and waits for updates. This is very early on in the init process.
5. init then continues doing it's normal stuff.
6. At the end of this stage the initrd init passes control over to run-init which deletes the initramfs from memory, mounts the real root filesystem and passes control to the /sbin/init program on it.
7. The boot process then continues as if it were a normal init.

1. The normal init scripts use the shell functions defined in /lib/lsb/init-functions to do logging etc. That file however sources a Splashy file called: /etc/lsb-base-logging.sh. Here the lsb log_end_msg() function is changed to call splashy_update to update the progress bar.
2. init.d/splashy then gets run as soon as possible by the real init (e.g. in /etc/rcS.d/03splashy). This script counts the number of log_end_msg()'s calls in the current runlevel (so each call progresses the bar the right amount) and starts Splashy in boot mode unless it is already running from initrd.
3. The log_end_msg() function determines when Splashy has reached 100% and tells Splashy to stop.

The shutdown process is essentially the same in reverse.

1. /etc/init.d/splashy is called from /etc/rc6.d/K01splashy or /etc/rc0.d/K01splashy with stop as its argument.
   1. This triggers Splashy to run in shutdown mode (progressbar in reverse)
2. On LSB systems, Splashy steps are calculated by /etc/lsb-base-logging.sh as before and each time a call to log_end_msg() is done, a step is added to the progressbar, which it's painted in reverse