Hell Labs

Slow booting plagues most Linux distributions today, and while this is not a such big issue for systems that are booted once a year, it becomes an annoyance in laptops or other computers you initialize every day. Different solutions for this problem have been proposed, but booting of a typical Linux system today still takes too much time. It has been said that the Asus Eeepc boots remarkably faster than regular Linux distributions, thanks to its “fastinit” system initialization program. A quick analysis of its workings shows what it essentally does, and it’s quite obvious: start the user interface as fast as possible, and initialize the rest later. A more detailed analysis allowed us to rewrite it, and even find a couple of bugs in the original code.

Judging from its calls, the program performs the tasks of a simplified Unix init and some initialization scripts. It handles signals, mount filesystems, creates basic files, brings up basic networking, initializes the random seed (not quite! see note below), opens terminals and finally runs the X server, while starting other non-essential services in the background. It is cleverly designed, and while can be optimized a little more, it does its job well on the Eeepc. I reimplemented fastinit by writing a program that makes the same calls, you can get it from my git repository with git clone http://helllabs.org/git/eeepc.git.

This reimplementation may be useful in alternative Linux distributions running in the Eeepc to boot as fast as the original OS. I don’t recommend using it on a regular computer because it lacks functionality found in SysV init. Also note that this version aims to accurately replicate the behavior of the original fastinit, so it contains a number of bugs and unoptimized features:

• Random seed initialization does not work. Note that the program redirects random-seed to /dev/null. If you fix that, it would still try to write an error message to /dev/urandom.
• There’s no need to try to handle SIGKILL and SIGSTOP.
• There’s also an attempt to handle signal 0.
• Some of the calls made with system() could be done in C, such as directory creation.

The reimplementation has been written for educational purposes and has not been tested (mainly because I don’t have an Eeepc). It may contain errors, so I advise reviewing the code and procceed with caution if you wish to give it a try.

This entry was posted on Monday, December 31st, 2007 at 8:58 am and is filed under code, eeepc, en, linux, reverseengineer. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.