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<title>Sys. function 69</title>
<text><b>KolibriOS Help</b></text>
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<h2>System function 69 - debugging.</h2>
<text>A process can load other process as debugged by set of corresponding bit by call to subfunction 7 of function 70.</br>
A process can have only one debugger; one process can debug some others. The system notifies debugger on events occuring with debugged process.</br> Messages are written to the buffer defined by subfunction 0.</br></text>
<text>Format of a message:</br>
+0: dword: message code;</br>
+4: dword: PID of debugged process;</br>
+8: there can be additional data depending on message code.</br></br>
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<text>Message codes:</br>
1 = exception in addition dword-number of the exception is given process is suspended;</br>
2 = process has terminated comes at any termination: both through the system function -1, and at "murder" by any other process (including debugger itself);</br>
3 = debug exception int 1 = #DB in addition dword-image of the register DR6 is given: bits 0-3: condition of the corresponding breakpoint (set by subfunction 9) is satisfied bit 14: exception has occured because of the trace mode (flag TF is set TF) process is suspended.</br></br>
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<text>When debugger terminates, all debugged processes are killed. If debugger does not want this, it must previously detach by
subfunction 3.</br></br>
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<text>All subfunctions are applicable only to processes/threads started from the current by function 70 with set debugging flag. Debugging of multithreaded programs is not supported yet.</br></br>
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<text>The full list of subfunctions:</br>
subfunction 0 - define data area for debug messages</br>
subfunction 1 - get contents of registers of debugged thread</br>
subfunction 2 - set contents of registers of debugged thread</br>
subfunction 3 - detach from debugged process</br>
subfunction 4 - suspend debugged thread</br>
subfunction 5 - resume debugged thread</br>
subfunction 6 - read from the memory of debugged process</br>
subfunction 7 - write to the memory of debugged process</br>
subfunction 8 - terminate debugged thread</br>
subfunction 9 - set/clear hardware breakpoint</br></br>
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<text>Value for register eax - 69 (SF_DEBUG).</br>
Values for register ebx:</br>
0 - SSF_SET_MESSAGE_AREA - subfunction 0 - define data area fror debug messages.</br>
1 - SSF_GET_REGISTERS - subfunction 1 - Get contents of registers of debugged thread.</br>
2 - SSF_SET_REGISTERS - subfunction 2 - Set contents of registers of debugged thread.</br>
3 - SSF_DETACH - subfunction 3 - detach from debugged process.</br>
4 - SSF_SUSPEND - subfunction 4 - suspend debugged thread.</br>
5 - SSF_RESUME - subfunction 5 - resume debugged thread.</br>
6 - SSF_READ_MEMORY - subfunction 6 - read from memory of debugged process.<br>
7 - SSF_WRITE_MEMORY - subfunction 7 - write to memory of debugged process.</br>
8 - SSF_TERMINATE - subfunction 8 - terminate debugged thread.</br>
9 - SSF_DEFINE_BREAKPOINT - subfunction 9 - set/clear hardware breakpoint.
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<text>created 23.08.2020 by Alex2003</text>
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