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************function_graph******************
********************************************
echo 0 > /sys/kernel/debug/tracing/tracing_on
trace-cmd start -p function_graph -g ip_rcv
trace-cmd stop
cat /sys/kernel/debug/tracing/trace

********************************************
cat tracing_on 
echo 1 > tracing_on 

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read() called when data sent from the device to user space
write() called when data sent from user space to the device
http://derekmolloy.ie/writing-a-linux-kernel-module-part-2-a-character-device/

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https://askubuntu.com/questions/645220/unable-to-connect-wifi-ubuntu-14-04-lts-hp-pavilion-network-driver-rtl8723be
sudo add-apt-repository ppa:hanipouspilot/rtlwifi
sudo apt-get update
sudo apt-get install rtlwifi-new-dkms linux-firmware

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#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/version.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/pci.h>
#include <linux/ioport.h>
#include <asm/unistd.h>
#include <linux/slab.h>
#include <linux/fs.h>

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/**
 * Function to perform jump to system memory boot from user application
 * Link: http://www.onarm.com/forum/64128/
 * Call function when you want to jump to system memory
 */
void JumpToBootloader(void) {
	void (*SysMemBootJump)(void);
	
	/**
	 * Step: Set system memory address. 

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Diagnostics in Braking Systems

EBS(Electronic Braking Systems)
30 ECUs

OBD(On Board Diagnostics)
Check its health

Off Board Diagnostics
A connector tool is connected to the network of ECUs

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1)
    #include <stdio.h>
    int main()
    {
        int a[4] = {1, 2, 3, 4};
        int b[4] = {1, 2, 3, 4};
        int n = &b[3] - &a[2];
        printf("%d\n", n);
    }
    

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/******************************************************************************

                            Online C Compiler.
                Code, Compile, Run and Debug C program online.
Write your code in this editor and press "Run" button to compile and execute it.

*******************************************************************************/

#include <stdio.h>
#include <stdint.h>

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#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>


typedef struct Intel_Hex{
  uint8_t length;
  uint32_t addr;
  uint8_t record_type;

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#include <stdio.h>
#include <stdint.h>

char hex_string[2];
int main(void)
{
    uint8_t check_sum = 242;

    sprintf(hex_string, "%02X", check_sum);
    for(int i=0; i<4;i++)