Startup diagnosis
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Diagnosing Startup Failures
When the XO laptop is powered-on, it makes a brief survey of the available I/O devices, then tries to read in and execute the operating system. The operating system then explores the hardware and begins operations. At various points in this process, software or hardware problems can result in a "hang". a power-off, or another problem. This page attempts to describe what you might see at such a hang, and what the possible causes might be.
Diagnosing Pretty Boot
XO laptops without "developer keys" typically start up by making a pretty screen with very little text on it. This adds to the laptop's charm, but makes diagnosis more interesting. On the positive side, it can be interpreted in any language, once you understand it.
The first screen shows grey with the "XO" logo in the middle. When there is nothing there besides the "XO", the laptop is still running Open FirmWare (boot firmware). When the firmware has located the operating system and has read it into memory (typically from the JFFS2 filesystem on the internal NAND flash chips), it puts a first dot below the XO logo.
Just after painting the first dot, the firmware gives up control of the machine to the operating system (typically the Linux kernel). The kernel then probes the available hardware, locates the root file system (typically the JFFS2 filesystem on the internal NAND flash chips), reads in the initial user program, and begins the scripted process of creating the running operating system.
I do not yet know when the second dot first appears. Failures when there is an XO logo and a single dot could be caused by a variety of problems.
Each subsequent dot indicates that a particular point in the progress of the Linux startup scripts has been reached. I do not yet know exactly when/why each dot appears.
Eventually a circle of about twenty dots sweeps around the XO logo, and part of the logo itself rotates to face each new dot. At the completion of the circle, a solid circle covers up the dots. I do not yet know when this circle appears.
When the grey XO logo and the solid grey circle are visible, a delay of many seconds arises. Eventually, after the X Window System server and the Sugar graphical user interface are running, the screen changes to include a colored XO logo, a black frame around the edges of the screen, and a Journal (book-like) icon at the bottom of the circle -- which has become the "donut" in which later activities are visible.
I do not yet know exactly when the colored screen first appears.
Diagnosing Check-Key Boot
The laptop's startup process becomes significantly more verbose if you hold the "Check" key on the game pad to the right of the screen (the rightmost of the four keys), as you press the power button to start it up. Asking the laptop owner to do this can sometimes produce information that helps to diagnose the problem.
Diagnosing Insecure Boot
XO laptops without Firmware Security or with a Developer Key produce a large amount of textual output as they start up. This text is very similar to the output of standard Fedora, Linux, or Unix system startup. This may allow people with a Unix background to more easily diagnose their problem.