Inveneo Linux 2 Guide

= Booting/Filesystems =

There are only two types of filesystems in Inveneo Linux: compressed, read-only filesystem images (squashfs) and RAM-based filesystems (tmpfs). Any data normally stored in a tmpfs filesystem which must persist across reboots is saved to persistent storage as a bzipped tar archive. The persistent storage is usually a flash disk, and is generally referred to as the Inveneo Linux 2 Guide. Since the host filesystem is only written to when specifically requested by the administrator and only needs to store a few files, it can use nearly any filesystem type. For simplicity and optimal legacy BIOS compatibility, Inveneo Linux uses FAT16 as the host filesystem type. As a result, a very simple bootloader ([syslinux TBD]) is all that is necessary to load the kernel.

Inveneo Linux takes advantage of the Linux kernel's initial RAM disk support to boot the system quickly. The initial RAM disk in Inveneo Linux is actually the entire post-boot filesystem with the exception of the /usr and /opt directories. Since busybox is installed to /bin, the system can reach far enough in the boot process to mount the rest of the filesystems. (In the future, it would be preferable to use the Linux kernel's newer [initramfs TBD] support since traditional RAM disks are inefficient.)

The kernel runs busybox's init, which is guided by /etc/inittab. inittab, in turn, runs /etc/init.d/rcS, the main boot script. This script runs all scripts (in alphabetical order) in the /etc/init.d directory which start with a capital 'S' followed by two digits. Generally these scripts are actually links (to other scripts in the /etc/init.d directory) in order to allow the same script to perform boot and shutdown actions. Finally, control returns to inittab, which calls /bin/logindefault to prevent the user from needing to enter a username and password.

If this is the first time this particular Inveneo Linux system is being booted (that is, if /home/root/etc/.configured doesn't exist), logindefault will log the user in as root in order to perform first-boot configuration. Otherwise, the user is logged in as 'default', Inveneo Linux's unprivileged user.

At this point, the user's login shell (busybox ash) is run, which sources /etc/profile. /etc/profile will set environment variables as needed and start X. Now xinit takes over. root's .xinitrc runs the first-boot script. 'default' has no .xinitrc normally, so the default xinitrc (/etc/X11/xinit/xinitrc) is used. The default xinitrc launches the file browser (ROX-Filer) and the window manager (jwm). Once xinit is complete, the system is ready to be used.

= Glossary =

host filesystem
The host filesystem resides on the persistent storage device, usually a flash drive. This is the only place data can be permanently stored. It takes the place of the hard drive in a normal computer system.

= Upstream Documentation =

= Filesystem Index =