Professional Device Drivers Interview Questions & Answers:

1. The major number identifies the _____ associated with the device.
a) driver
b) protocol
c) port
d) none of the mentioned

a) driver

2. The kernel identifies the driver with its:
a) module
b) major number
c) device file
d) none of the mentioned

b) major number

3. In linux kernel 2.4, we can have:
a) 256 character drivers only
b) 256 block drivers only
c) 256 character drivers and 256 block drivers at the same time
d) none of the mentioned

c) 256 character drivers and 256 block drivers at the same time

4. The connection between the device file and device driver is based on the:
a) name of device file
b) number of device file
c) both (a) and (b)
d) none of the mentioned

b) number of device file

5. Do you know what is the output of this program?

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

int main()
{
char *ptr;
memcpy(ptr,"google",11);
printf("%sn",ptr);
return 0;
}
a) google
b) segmentation fault
c) syntax error
d) none of the mentioned

b) segmentation fault
Explanation:
Memory must be allocated to pointer "ptr".
Output:
[root@localhost google]# gcc -o san san.c
[root@localhost google]# ./san
Segmentation fault (core dumped)
[root@localhost google]#

6. This program will allocate the memory of ___ bytes for pointer "ptr".

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

int main()
{
int *ptr;
ptr = realloc(0,sizeof(int)*10);
return 0;
}
a) 0
b) 10
c) 40
d) none of the mentioned

c) 40
Explanation:
If the first argument of realloc() is NULL, then it behaves just like malloc().

7. What is the output of this program?

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

int main()
{
char *ptr;
free(ptr);
return 0
}
a) this program will print nothing after execution
b) segmentation fault
c) Aborted (core dumped)
d) none of the mentioned

c) Aborted (core dumped)

8. Tell me what is the output of this program?

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

int main()
{
char *ptr;
memcpy(ptr,"google",11);
printf("%sn",ptr);
return 0;
}
a) google
b) segmentation fault
c) syntax error
d) none of the mentioned

b) segmentation fault
Explanation:
Memory must be allocated to pointer "ptr".
Output:
[root@localhost google]# gcc -o san san.c
[root@localhost google]# ./san
Segmentation fault (core dumped)
[root@localhost google]#

9. What is the output of this program?

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

int main()
{
char *ptr;
ptr = (char*)malloc(sizeof(char)*11);
strcpy(ptr,"google");
printf("%dn",*ptr);
return 0;
}
a) s
b) google
c) 115
d) segmentation fault

c) 115
Explanation:
This program will print the equivalent decimal value at location pointed by "ptr".
Output:
[root@localhost google]# gcc -o san san.c
[root@localhost google]# ./san
115
[root@localhost google]#

10. Which one of the following in true about this program?

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

int main()
{
char *ptr;
printf("%pn",ptr);
ptr = (char *)malloc(sizeof(char));
printf("%pn",ptr);
return 0;
}
a) this program will give segmentation fault
b) this program will print two same values
c) this program has some syntax error
d) none of the mentioned

d) none of the mentioned
Explanation:
This program will print two different values.
Output:
[root@localhost google]# gcc -o san san.c
[root@localhost google]# ./san
0x4a77cff4
0x980c008
[root@localhost google]#