is printf privileged instruction?

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By : if-then

Date : November 23 2020, 09:01 AM

I hope this helps . since I/O instructions are privileged instructions that require mode switch from user to kernel, is printf also considered a privileged instruction? is there mode switch when performing printf instructions? ,
is printf also considered a privileged instruction?

code :

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What is a privileged instruction?

By : jodaka

Date : March 29 2020, 07:55 AM

Hope this helps To answer the question, a privileged instruction is a processor op-code (assembler instruction) which can only be executed in "supervisor" (or Ring-0) mode. These types of instructions tend to be used to access I/O devices and protected data structures from the windows kernel.
Regular programs execute in "user mode" (Ring-3) which disallows direct access to I/O devices, etc...

Privileged instruction in C

By : user3005987

Date : March 29 2020, 07:55 AM

may help you . There are ways around this. See here for instance.

privileged instruction in Java

By : Flying Zone

Date : March 29 2020, 07:55 AM

seems to work fine In a conventional Java implementation, your only option is to implement the code that executes the privileged instructions in a native method that you call using JNI or JNA. And it won't do you any good ... because the hardware / operating system will prevent the instructions from running. (You will get an illegal instruction trap ... and the program will be killed.)

Privileged instruction runtime error on strcpy()

By : meems

Date : March 29 2020, 07:55 AM

This might help you I'm having an issue upgrading a C++ Builder 6 project to C++ Builder XE3. Currently my problem is this: When compiled and run in Release mode, the project throws the "Privileged instruction." error which I've tracked down to two different for loops surrounding calls to strcpy(). I've attempted changing this to strncpy() and including the character string size, but to no avail. All I know is that when I comment out these two lines, the error goes away. , This was fixed by researching the comment from @UlrichEckhardt:

code :

/** Main.cpp */
char *ADC_names[] = {
   "String 1",
    "String 2",
    "String 3",
    "String 4",
    "String 5",
    "String 6",
    "String 7",
    "String 8"
};

void __fastcall TForm1::ReadCalFromUnitBtnClick(TObject *Sender) {
    memset(calibr, 0, sizeof(calibr));
    for (int j = 0; j < 8; j++) {
        strcpy(calibr[j].name, ADC_names[j]);
    }
}

Switch to Kernel Mode - Privileged Instruction

By : Antônio Luiz Souza

Date : March 29 2020, 07:55 AM

Any of those help Lets see it step by step:
A process is running. An exception comes while the process is running. The process is interrupted to call the exception or interrupt handler. The instructions, known as the trap or system call handler, read the details of the requested service + arguments, and then perform this request in kernel mode. Now we are back in user mode at the position where the interrupt was called.