Linux Device Drivers

Front 1

In the Unix/Linux Model, what sits directly above the hardware and controls all access to hardware?

Back 1

The Unix/Linux Kernel Hardware Control module.

Front 2

Which two Linux Kernel entities interface directly with Hardware Control Module?

Back 2

1.Device Drivers
and
2. The Process Control Subsystem.

Front 3

Of which 3 sub-modules is the Process Control Subsystem made?

Back 3

Scheduler,
Memory Management,
Inter-process Communication

Front 4

Which two kernel modules sit above the device driver module?

Back 4

Character
and
Block
modules.

Front 5

To which other module does the Character module connect?

Back 5

The File Subsystem

Front 6

What separates the Block module from the File Subsystem Module?

Back 6

the Buffer Cache module

Front 7

To which 2 other modules does the File Subsystem connect?

Back 7

The System Call Interface module
and
the Process Control Subsystem module

Front 8

To which 4 modules does the System Call Interface connect?

Back 8

1. User's programs and
2. Program's libraries,
3. File Subsystem,
4. Process Control Subsytem

Front 9

Name the 5 most commonly used function calls

Back 9

1.open,
2. read
3. write
4. ioctl
5. close

Front 10

Name 3 Device Driver Supporting functions that allow the kernel to read/write user address space.

Back 10

1. get_*fs (),
2. put_*fs (),
3. memcpy_*fs ()

Front 11

How does a device driver obtain device identifying information?

Back 11

Major ()
and
Minor ()
supporting functions.

Front 12

Which supporting functions read and write a byte from device i/o ports as fast as possible?

Back 12

1. inb ()
2. outb ()

Front 13

Which supporting functions read and write a byte from device i/o ports after a pause?

Back 13

1. inb_p ()
2. outb_p ()

Front 14

How is the kernel made aware of the presence of a device?

Back 14

register_*dev () REGISTERs the device with the kernel.

Front 15

How does a device get the attention of the kernel?

Back 15

Through the use of an interrupt request.

Front 16

How does a device get an interrupt to use?

Back 16

A device driver makes a call to
request_irq ()

Front 17

How is an interrupt handler installed?

Back 17

A successful call to
request_irq ()
installs the interrupt handler.

Front 18

How can a device driver prevent interrupts from being serviced?

Back 18

The cli () function keeps interrupts from being acknowledged.

Front 19

How does the device drive re-enable interrupt servicing?

Back 19

the sti () function allows interrupt acknowledgement.

Front 20

How can a process be notifies when an interrupt has occured?

Back 20

The
irqaction ()
function call registers the interrupt like a signal.

Front 21

Must interrupts be returned after being obtained by
irqaction ()
and
request_irq

Back 21

yes, with the function
free_irq ()

Front 22

How does a device driver get and return a block of memory no larger than 4096 bytes?

Back 22

kmalloc ()
and
kfree *()

Front 23

How do you print within the kernel?

Back 23

printk ()

Front 24

How does a process wait for an event without wasting processor cycles?

Back 24

*sleep_on ()
puts a wait_queue entry in the list so that the process can be awakened on that event.

Front 25

How does a process get restarted after the event for which it was waiting happens?

Back 25

wake_up* ()
wakes up the process that was put to sleep by a matching *sleep_on().

Front 26

How is a process added to a wait queue?

Back 26

select_wait ()
adds a process to the correct select wait queue.

Front 27

Which system call returns information about the process, user or group?

Back 27

sys_get* ()

Front 28

How can a device driver determine if an inode is mounted on a file system with the specfied flag?

Back 28

IS_* ()

Front 29

What function is called when a request is satisfied or aborted?

Back 29

end_request ()

Front 30

How can a function be executed only after a specified amount of time has expired?

Back 30

add_timer ()

Front 31

A device driver provides which 4 features?

Back 31

A set of routines that communicate with a hardware device and provide a uniform interface to the operating system kernel.
A self-contained component that can be added to, or removed from, the operating system dynamically.
Management of data flow and c ontrol between user programs and a peripheral device.
A user-defined section of the kernel that allows a program or a peripheral device to appear as a `` /dev '' device to the rest of the system's software.

Front 32

What is the function of the <xxx>_fops structure in the device driver?

Back 32

It is a list (structure, of type "file_operations"), filled with the subroutines (xxx_open(), xxx_close(), xxx_init() ) found in the driver which is used to "register" the basic i/o functions with the Virtual File System Switch.