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System Panics

In most cases, if the kernel detects an error in operation an appropriate error code is returned by the function in question (GS/OS calls, ToolBox calls, or system calls as described above). However, there are rare circumstances where the kernel detects what should be an impossible condition. This can happen due to bugs in the kernel, because the kernel was overwritten by a buggy program, or for any number of other reasons.

When the kernel does come across such an error, system operation cannot continue and what ensues is called a system panic. Panics are very easily noticed- the kernel will print an error message on the screen and ensure that the text screen is visible, turning off any graphics mode if necessary. The kernel then sets the text and background colors to red on white - a very noticeable condition. At that point, the kernel turns off context switching to prevent any background process or other interrupt driven code from further confusing the system. This is done mainly to prevent damage to disk directory structures by a bad system.

When a system panic does occur, the only thing you can do is reboot your system. If you can reliably reproduce a system panic, please record the panic message and the sequence of events necessary to evoke the panic and report the information to Procyon, Inc.


next up previous index
Next: Appendix B: Miscellaneous Programming Up: Appendix A: Making System Previous: System Call Error Codes   Index
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