Transcript Device Driver

Device Driver
Presented By: Syed Zulfiqar Ali
Qurat Ul Ain Aslam
Samina Kanwal
Sana Zahid
Presented To: Miss Madiha Zafar
What is a device driver?
• A device driver is a system program or application that
controls a particular type of device that is connected to your
computer.
• A device driver or software driver is a computer program,
application allowing higher-level computer programs to
interact with a hardware device.
• A device driver essentially converts the more generic
input/output instructions of your operating system to
message that the device type can understand and interpret.
Continue…
Why a device driver ?
• A device driver simplifies programming by acting as an abstraction layer
between a hardware device and the applications or operating systems
that use it
• The higher-level application code can be written independently of
whatever specific hardware device it will ultimately control, as it can
interface with it in a standard way, regardless of the underlying hardware.
• The device-driver accepts the generic high-level commands and breaks
them into a series of low-level device-specific commands as required by
the device being driven.
Why a device driver ? .. [contd.]
• Device Drivers can provide a level of security as they can run in kernelmode, thereby protecting the operating system from applications running
in user-mode.
Ring 3
Ring 2
Ring 1
Lest Privileged
Ring 0
Kernel
Device Drivers
Device Drivers
Most Privileged
Applications
Privilege rings available
Does every hardware or a device connected
to pc requires device driver?
• No when you buy an operating system many device drivers are
built in into operating system itself.
• however 3-6 months down the line if you attach a device which
your operating system doesnot understand then device driver is
required
How does a driver communicates with
hardware?
• A device driver typically communicates with the device through
the computer bus or communications subsystem to which the
hardware is connected
Device Driver design
Logical
Layer
Physical
Layer
Logical layers process
data for a class of
devices such as ethernet
ports or disk drives
Physical layers
communicate with
specific device instances
A serial port needs to
handle standard
communication protocols
such as XON/XOFF . This
is managed by a serial
port logical layer.
The logical layer needs
to communicate with a
particular serial port
chip, the physical layer
addresses this.
Device Driver Design …[Contd.]
Physical
layer
Logical
layer
OS
Hardware
request
Development
• Writing a device driver requires an in-depth understanding of how the
hardware and the software works for a given platform function.
• Because drivers require low-level access to hardware functions in order
to operate, drivers typically operate in a highly privileged environment
and can cause disaster if they get things wrong.
• In contrast, most user-level software on modern operating systems can
be stopped without greatly affecting the rest of the system.
• Even drivers executing in user mode can crash a system if the device is
erroneously programmed.
• These factors make it more difficult and dangerous to diagnose
problems.
Kernel mode vs. user mode
• Device drivers, particularly on modern Microsoft
Windows platforms, can run in kernel-mode (Ring 0 on x86 CPUs)
or in user-mode (Ring 3 on x86 CPUs).
• The primary benefit of running a driver in user mode is improved
stability, since a poorly written user mode device driver cannot
crash the system by overwriting kernel memory.
How Drivers are accessed ?
• System initialization
• System calls from user processes
• User-level requests
• Device interrupts
• Bus reset
Application
• Because of the diversity of modern hardware and operating systems, drivers
operate in many different environments.Drivers may interface with:
Are there any types in device driver?
Yes there are two types
• A:
Open Driver file usually has a file name suffix of dll or exe
• B:
A virtual device driver with suffix VXD.
Virtual Device Drivers
• Virtual device drivers represent a particular variant of device
drivers. They are used to emulate a hardware device, particularly
in virtualization environments, for example when a DOS program is
run on a Microsoft Windows computer or when a guest operating
system is run on, for example,linux iis running virtually under
windows.
• Instead of enabling the guest operating system to dialog with
hardware, virtual device drivers take the opposite role and emulate
a piece of hardware, so that the guest operating system and its
drivers running inside a virtual machine can have the illusion of
accessing real hardware.
• There are several variants of virtual device drivers, such
as VxDs, VLMs, VDDs.
Device Drivers List Installed On A System…
Sound Driver Detail And Files Detail…
Questions???
That’s All…