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The mips, ia32 and amd64 platforms provide additional commands regarding
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The mips, ia32 and amd64 platforms provide additional commands regarding
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debugging facility - set and clear hardware breakpoints and watchpoints.
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debugging facility - set and clear hardware breakpoints and watchpoints.
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\section{Emergency Functions}
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\section{Emergency Functions}
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It may happen that the IPC communication dies or that there are some
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It may happen that the IPC communication dies or that there appear some
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problems in the communication chain
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problems in the communication chain
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{\em keboard driver} - {\em console} - {\em output driver}.
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{\em keboard driver} - {\em console} - {\em output driver}.
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As long that at least the keyboard driver works, pressing Escape key three
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As long that at least the keyboard driver works, pressing Escape key three
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times transfers control to the KConsole immediately. If the screen is not
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times transfers control to the KConsole immediately. Because the screen is not
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updated, the user should press Enter to see the kconsole prompt.
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updated, the user should press Enter to see the kconsole prompt.
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If a kernel panic occurs, the error handling automatially switches control
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If a kernel panic occurs, the error handling automatially switches control
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to the KConsole and allows users to inspect the failed kernel online.
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to the KConsole and allows users to inspect the failed kernel online.
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On the SMP system the other processors are halted immediately. The kernel
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On the SMP system the other processors are halted immediately. The kernel
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contains its symbol table, so you can probably read some useful information
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contains its symbol table, so you can probably read some useful information
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about the exact place where the panic occured.
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about the exact place where the panic occured.
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\section{How to Do a Kernel Panic}
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Kernel panic is extremely rare in HelenOS. However, if the user wishes to
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simulate it, KConsole contains proper commands. For example the following
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command simulates a write to the unmapped address 0x4:
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\begin{verbatim}
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kconsole> set4 4 0
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\end{verbatim}
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To test the autodebugging possibilities of the IA32 platform, the following
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sequence can be executed:
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\begin{verbatim}
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kconsole> bkpts
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0. 0x80032010 in (NULL)
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    Count(0)
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kconsole> set4 0x80032010 0
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**** Found ZERO on address 0x0 ****
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Reached breakpoint 0:0x8011552a(generic/src/console/cmd.o:cmd_set4)
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***Type 'exit' to exit kconsole.
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debug>
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\end{verbatim}
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\section{KLog}
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To avoid disturbing the framebuffer driver with kernel messages, a circular
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buffer communication between kernel and userspace area is established.
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Non-critical messages are sent to the
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KLog application. User can see messages about task faults
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and task cleanup completion.
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\section{IPCC - testing applicatoin}
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To test thouroughly some aspects of the IPC and task
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\section{Tetris}
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