Download Chapter 5

Slide 5-1
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-2
Device
Management
Copyright © 2004 Pearson Education, Inc.
5
Operating Systems: A Modern Perspective, Chapter 5
Input/Output Devices
Slide 5-3
Output Device
Input Device
Copyright © 2004 Pearson Education, Inc.
Processor
Operating Systems: A Modern Perspective, Chapter 5
I/O devices
Slide 5-4
• Each I/O device consists of a device controller and
the physical device itself.
• Devices:
- storage devices: for permanent storage (e.g.
disk, tape)
- communication devices: to transfer data from
the computer to another machine (e.g. keyboard, a
terminal display, or a serial port to a modem or a
network).
• Devices can be character-oriented (e.g. a terminal)
or block-oriented (e.g. a disk)
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-5
I/O Devices (cont.)
• Device controller: hardware that connects
the device to the computer’s address and
data bus:
– continuously monitors and controls the
operation of the device.
– provides an interface to the computer: a set of
components that the CPU can manipulate to
perform I/O operations. Need to have a
standard interface so that devices can be
interchanged.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
I/O devices
Slide 5-6
Application Program
Device manager
System Bus
Device Controller
Device
• Device Manager: consists of a collection of device drivers
– hide the operation details of each device controller from
application programmer.
– provide a “common” interface to all sorts of devices. e.g.
Open, close (to allocate/deallocate device),
read/write, etc.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-7
The Device Driver Interface
…
write(…);
…
Device Interface
Terminal
Driver
Printer
Driver
Disk
Driver
Terminal
Controller
Printer
Controller
Disk
Controller
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-8
Infrastructure and device drivers
• Device Manager is composed of device
manager infrastructure (device independent
part) and a collection of device drivers
(device dependent part)
• Infrastructure:
– exports the common device interface as system
calls
– Routes calls on the generic interface to specific
device driver functions
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-9
Device Management Organization
Application
Process
System Interface
File
Manager
Device-Independent
Device-Dependent
Hardware Interface
Command
Status
Data
Device Controller
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-10
System Call Interface
• Functions available to application programs
• Abstract all devices (and files) to a few
interfaces
• Make interfaces as similar as possible
– Block vs character
– Sequential vs direct access
• Device driver implements functions (one
entry point per API function)
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-11
Example: BSD UNIX Driver
open
close
ioctl
read
write
strategy
select
stop
Copyright © 2004 Pearson Education, Inc.
Prepare dev for operation
No longer using the device
Character dev specific info
Character dev input op
Character dev output op
Block dev input/output ops
Character dev check for data
Discontinue a stream output op
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-12
I/O Strategies
•
•
•
•
Direct I/O with polling
DMA I/O with polling
Direct I/O with interrupts
DMA I/O with interrupts
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Performing a Write Operation
Slide 5-13
Device driver:
1. While (device is not idle)
keep checking;
2. Set command register to WRITE and set busy flag to 1.
3. Move address of source into address register of controller
4. Move data to be written into data registers of the controller.
Device-Controller:
1. Store data from data registers into the device.
2. When operation is completed, clear busy flag and set done
flag to 1.
5. Wait for busy flag to be cleared
when busy flag becomes clear, clear done flag to 0.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Performing a Write Operation
Slide 5-14
Device Driver:
while (device.busy || device.done)
<keep checking>;
device.data[0] = <value to write>;
device.address[0] = <address of source>
device.command = WRITE ; this also sets busy flag
while (device.busy)
<keep checking>;
device.done = 0;
return to calling process;
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Performing a Read Operation
Slide 5-15
while (device.busy || device.done)
<keep checking>;
device.command = READ ; this also sets busy flag
device.address[0] = <address of destination>
while (device.busy)
<keep checking>;
Move value in device.data[0] to memory or CPU
register;
device.done = 0;
Note:
• Polling is used to determine status of I/O device
• while device operates, the CPU waits. When device is done,
CPU continues with rest of program
=> Direct I/O with polling
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Polling I/O Read Operation
read(device, …);
1
System Interface
Data
read function
5
write function
2
3
4
Hardware Interface
Command
Status
Data
Device Controller
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-16
Overlapping the Operation of a
Device and the CPU
. . .
read(dev_I, “%d”, x);
y = f(x)
. . .
. . .
startRead(dev_I, “%d”, x);
. . .
While(stillReading()) ;
y = f(x)
. . .
Data on device
Variable x
Register
Memory
CPU
Device dev_I
Copyright © 2004 Pearson Education, Inc.
Slide 5-17
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-18
Overlapping CPU-Controller
Operations in a Process
App
I/O Ctlr
t1
Copyright © 2004 Pearson Education, Inc.
t2 t3 t4
t5
t6
t7
Operating Systems: A Modern Perspective, Chapter 5
t8
t9
Slide 5-19
Overlapping Processing and I/O
App 1
App 2
I/O Ctlr
t1
Copyright © 2004 Pearson Education, Inc.
t2
t3
Operating Systems: A Modern Perspective, Chapter 5
t4
Interrupt Driven I/O
Slide 5-20
• Instead of having the CPU continuously poll status
register of I/O device(s), have I/O device notify CPU
when it has completed an I/O operation.
– CPU initiates an I/O operation as described before
– as I/O device performs the operation, CPU is
switched to another process (thru the process
scheduler).
– When the I/O device is done, it notifies the CPU by
sending it an interrupt signal.
– The CPU switches control to an interrupt handler to
service the interrupt.
– The interrupt handler completes I/O operation and
returns control to interrupted process.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Interrupt Driven I/O
• An InterruptRequest flag is incorporated in the
CPU
• Whenever an I/O device has completed its I/O
operation, it sets the InterruptRequest flag to 1.
• Conceptually, this can be done by connecting the done
flags of all I/O controllers to the InterruptRequest
flag through an OR gate.
• Control unit of the CPU must check the
InterruptRequest flag before it starts each
instruction. If flag is set, it jumps to an interrupt
handler program.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-21
Slide 5-22
Interrupt Driven I/O
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Fetch-Execute Cycle with
Interrupt
PC = <Machine-Start-Address> ;
IR = Memory[PC] ;
haltFlag = CLEAR ;
Decode(IR);
while (haltFlag not SET) {
Execute(IR);
PC = PC + InstructionSize;
if (InterruptRequest) {
save current PC; // (e.g. in system stack)
PC = AddressOfInterruptHandler;
}
IR = Memory[PC] ;
Decode(IR);
}
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-23
Slide 5-24
Interrupt Handler
The Interrupt Handler is a program that is part of the
device manager. Each time it is called it does the
following:
1. Save the state of the interrupted process: save the
contents of CPU registers (all registers) and load
CPU registers with its own values:
Context Switch
2. Determine which I/O device caused the interrupt
3. Branch to the device driver associated with
that device.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Interrupt Handler
Slide 5-25
Interrupt_Handler
{
clear InterruptRequest flag;
saveProcessorState(); // Context Switch
for (i=0; i < Number_of_devices; i++)//poll
if (device[i].done == 1)
goto device_driver(i);
}
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-26
Device Driver
• The device driver is a program that is part of the device
manager. When called, it does the following:
– determine the cause of the interrupt
– complete the I/O operation
– clear the done flag of the device controller status
register
– restore the state of the interrupted process
context switch
– return control to interrupted process
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Interrupt Vector
Slide 5-27
How can we avoid having the interrupt handler poll all
the devices to determine which one caused the
interrupt?
• Replace the InterruptRequest flag with an
interrupt vector, ie. a collection of flags, one flag
for each device.
• Replace the OR gate with a vector of interrupt request
lines one for each device.
• An Interrupt Vector Table: a table of pointers to device
drivers : entry i of the table stores the address of device
driver i.
• The interrupt vector table is generally stored at a fixed
location in memory (e.g. first 100 locations).
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Race Condition
What if a second interrupt occurs while the first
is being processed? two possibilities:
1. Disable all other interrupts while an interrupt
is being processed
– use an InterruptEnabled (IE) flag in CPU
– provide instructions to set and clear the (IE) flag
– Control unit must check the (IE) flag before
processing any interrupt.
if (InterruptRequest & InterruptEnabled ) {
disableInterrupts();
save current PC and other CPU regs;
PC = address of interrupt handler;
}
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-28
Slide 5-29
Race Condition
2. Enable other interrupts while an interrupt is being
processed
– Must use system stack to save PC and state of the
interrupted process.
– Must use a priority scheme.
– Part of the interrupt handler routine should not be
interrupted.
• Most CPUs have two types of interrupts:
– maskable interrupts: can be interrupted
– un-maskable interrupts: can not be interrupted
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Performing a Read Operation
•
•
•
•
Slide 5-30
Read(device_i, "%d", x)
CPU is executing some process (say process A)
Process A makes a request for a read operation to
device i. This is done thru a system call to the OS
The device manager of the OS check validity of
system call and if valid, invokes the device driver
of device i.
The device driver queries the control status
register (CSR) of device i to determine whether the
device is idle. If the device is busy, the driver waits
for it to become idle. Device driver may also have a
queue of waiting I/O requests.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Performing a Read Operation
(cont.)
• The driver stores a READ command into the
controller’s Command register ==> device Busy
bit set to 1.
• The CPU is switched to another process B while
the I/O operation is being processed (device
driver invokes CPU scheduler)
• Eventually the device completes the READ
operation and raises an interrupt to the CPU
• The CPU is switched from process B to the
interrupt handler.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-31
Performing a Read Operation
(cont.)
Slide 5-32
• The interrupt handler determines which device caused the
interrupt and calls the device driver of device_i.
• The device driver determines what needs to be done and
copies the contents of the controller’s data register(s) into
the process space of process A (how does the device
driver know which process?)
• when the read operation is done, the device driver clears
the done flag of the device controller and returns control to
the interrupted process (i.e. process B)
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Device Status Table
Slide 5-33
• While an I/O operation is being done, the CPU
may be switched to some other process (other
than the one that requested the I/O operation)
• At any point of time, there may be several I/O
requests pending by various processes
• When a device driver is called to finish an I/O
operation, how does it know to which process the
I/O operation belongs?
• Device status table: a table containing
information about each I/O device.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-34
Device Status Table (cont.)
• Contains an entry for each I/O device.
• Each entry contains such information as:
– device type, address, state (idle, busy, not functioning,
etc.)
– if device is busy:
• the type of operation being performed by that device
• the process ID of the process that issued the
operation
• for some devices: a queue of waiting requests for
that device
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Performing Read Operation
Slide 5-35
• CPU is executing some process (say process A)
• Process A makes a request for an read operation
to device i. This is done thru a system call to the
OS
• The device manager of the OS, invokes the device
driver of device i.
• The device driver queries the CSR of device i to
determine whether device i is idle. If the device is
busy, the driver waits for it to become idle (or
queues process if there is a queue). Else if the
device is idle:
• If the device is idle: The driver stores a read
command into the controller’s Command register
==> device Busy bit set to 1.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Performing Read Operation (cont.)
Slide 5-36
• The driver saves information regarding the I/O
operation in the device status table.
• The status of process A is changed from running
to blocked
• The device driver invokes the CPU scheduler,
which switches the CPU to another process B
• Eventually the device completes the operation and
interrupts the CPU
• The CPU is switched to the interrupt handler
• Interrupt handler determine which device caused
the interrupt and calls the device driver of device i.
• The device driver retrieves information about the
I/O operation on device i from the device status
table ==> process A issued I/O operation
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-37
Performing Read Operation
(cont.)
• The device driver copies the contents of the
controller’s data register(s) into the process
space of process A.
• Process A status should be changed from
blocked to ready.
• If there is a queue of requests for device_I,
dispatch next request.
• the device driver returns control to the
interrupted process (i.e. process B).
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-38
Interrupt-driven I/O Operation
read(device, …);
1
9
8b
Data
System Interface
Device Status Table
4
read driver
2
7
Device
Handler
write driver
6
3
Interrupt
Handler
5
Hardware Interface
Command
Status
Data
Device Controller
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
8a
Device Independent Function Call
Trap Table
funci(…)
dev_func_i(devID, …) {
// Processing common to all devices
…
switch(devID) {
case dev0: dev0_func_i(…);
break;
case dev1: dev1_func_i(…);
break;
…
case devM: devM_func_i(…);
break;
};
// Processing common to all devices
…
}
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-39
Driver-Kernel Interface
Slide 5-40
• Drivers are distinct from main part of kernel
• Kernel makes calls on specific functions,
drivers implement them
• Drivers use kernel functions for:
–
–
–
–
Device allocation
Resource (e.g., memory) allocation
Scheduling
etc. (varies from OS to OS)
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Reconfigurable Device Drivers
Slide 5-41
System call interface
open(){…}
read(){…}
Entry Points for Device j
etc.
Driver for Device j
Copyright © 2004 Pearson Education, Inc.
Other
Kernel
services
Operating Systems: A Modern Perspective, Chapter 5
Handling Interrupts
Device driver J
int read(…) {
// Prepare for I/O
save_state(J);
out dev#
// Done (no return)
}
Device status table
J
Device interrupt handler J
void dev_handler(…) {
get_state(J);
//Cleanup after op
signal(dev[j]);
return_from_sys_call();
}
Interrupt Handler
Device Controller
Copyright © 2004 Pearson Education, Inc.
Slide 5-42
Operating Systems: A Modern Perspective, Chapter 5
Handling Interrupts(2)
Device driver J
Device interrupt handler J
int read(…) {
…
out dev#
// Return after interrupt
wait(dev[J});
return_from_sys_call();
}
void dev_handler(…) {
//Cleanup after op
signal(dev[j]);
}
Interrupt Handler
Device Controller
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-43
The Pure Cycle Water Company
Customer Office
Water Company
Returning the Empties
Water Producer
Water Consumers
Delivering Water
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-44
Slide 5-45
Hardware Buffering
Process
Controller
Process
Controller
Controller
Data
A
Device
Device
Unbuffered
Copyright © 2004 Pearson Education, Inc.
Process
B
Process reads bi-1
Controller reads bi
A
B
Device
Process reads bi
Controller reads bi+1
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-46
Driver
Double Buffering in the Driver
Process
Process
A
A
B
Hardware
Controller
A
B
Device
Copyright © 2004 Pearson Education, Inc.
B
Controller
A
B
Device
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-47
Circular Buffering
Buffer j
Buffer i
To data consumer
From data producer
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-48
I/O Buffering
A buffer is a memory area used to store data while it
is being transferred between two devices or
between a device and an application.
• Used to reduce the effects of speed mismatch
between I/O device and CPU or among I/O
devices.
• Generally used to allow more overlap between
producer and consumer
==> more overlap between the CPU and I/O devices.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-49
Compute vs I/O Bound
Compute-bound
Time
I/O-bound
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
A Generic Communications Device
Slide 5-50
Bus
Generic
Controller
Communications
Controller
Local
Device
Cabling connecting the
controller to the device
Device
•Printer
•Modem
•Network
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Serial Port
CPU
Memory
Serial
Device
• Printer
• Terminal
• Modem
• Mouse
• etc.
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-51
Serial Port
Slide 5-52
Device Driver API
Device Driver
Software on the CPU
• Set UART parms
•read/write ops
•Interrupt hander
UART API
•parity
•bits per byte
•etc.
Bus Interface
Serial Device
(UART)
RS-232 Interface
• 9-pin connector
• 4-wires
• bit transmit/receive
• ...
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Adding a Modem
CPU
Memory
Serial
Device
Modem
• Dialing & connecting
• Convert analog voice to/from digital
• Convert bytes to/from bit streams
• Transmit/receive protocol
Phone
Switched Telephone Network
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-53
Slide 5-54
Serial Communication
Device Driver
•Set UART parms
•read/write ops
•Interrupt hander
Driver-Modem Protocol
• Dialing & connecting
• Convert analog voice to/from digital
• Convert bytes to/from bit streams
• Transmit/receive protocol
Copyright © 2004 Pearson Education, Inc.
Serial Device
RS-232
Modem
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-55
Exploiting the Phone Network
Logical Communication
CPU
Memory
CPU
Comm
Device
Comm
Device
Modem
Modem
Phone
Phone
Switched Telephone Network
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Memory
Slide 5-56
Data Networks
• Technology focus includes protocols and software
(more on this later … Chapter 15 and beyond ...)
Logical Communication
CPU
Memory
Network
Device
Network
Device
Data Network
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
CPU
Memory
Rotating Media
Track (Cylinder)
(a) Multi-surface Disk
Copyright © 2004 Pearson Education, Inc.
(b) Disk Surface
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-57
Cylinder
(set of tracks)
(b) Cylinders
Slide 5-58
Storage Device
Device Driver API
Driver
• Get disk description
• Set SCSI parms
•read/write ops
• Interrupt hander
SCSI API
•commands
•bits per byte
•etc.
Controller
(SCSI)
Magnetic Disk
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-59
Disk Optimizations
• Transfer Time: Time to copy bits from disk
surface to memory
• Disk latency time: Rotational delay waiting
for proper sector to rotate under R/W head
• Disk seek time: Delay while R/W head
moves to the destination track/cylinder
• Access Time = seek + latency + transfer
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-60
Optimizing Seek Time
• Multiprogramming on I/O-bound programs
=> set of processes waiting for disk
• Seek time dominates access time =>
minimize seek time across the set
• Tracks 0:99; Head at track 75, requests for
23, 87, 36, 93, 66
• FCFS: 52+ 64 + 51 + 57 + 27 = 251 steps
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-61
Optimizing Seek Time (cont)
• Requests = 23, 87, 36, 93, 66
• SSTF: (75), 66, 87, 93, 36, 23
– 11 + 21 + 6 + 57 + 13 = 107 steps
– Subject to starvation
• Scan: (75), 87, 93, 99, 66, 36, 23
– 12 + 6 + 6 + 33 + 30 + 13 = 100 steps
• Look: (75), 87, 93, 66, 36, 23
– 12 + 6 + 27 + 30 + 13 = 87 steps
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-62
Optimizing Seek Time (cont)
• Requests = 23, 87, 36, 93, 66
• Circular Scan: (75), 87, 93, 99, 23, 36, 66
– 12 + 6 + 6 + home + 23 + 13 + 30 = 90 + home
• Circular Look: (75), 87, 93, 23, 36, 66
– 12 + 6 + home + 23 + 13 + 30 = 84 + home
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
Slide 5-63
MS Disk Description
0x00
0x03
0x0b
0x0d
0x10
0x11
0x13
0x15
0x16
0x18
0x1a
0x1c
0x1e
Copyright © 2004 Pearson Education, Inc.
0x02
0x0a
0x0c
0x0f
0x10
0x12
0x14
0x15
0x17
0x19
0x1b
0x1d
…
<a jump instruction to 0x1e>
Computer manufacturer name
Sectors per cluster (MS-DOS reads/writes a cluster of sectors)
Reserved sectors for the boot record
Number of FATs
Number of root directory entries
Number of logical sectors
Medium descriptor byte (used only on old versions of MS-DOS)
Sectors per FAT
Sectors per track
Number of surfaces (heads)
Number of hidden sectors
Bootstrap program
Operating Systems: A Modern Perspective, Chapter 5
NT Driver Organization
Data Flow
I/O Portion of Native API
Filter Driver
Intermediate Driver
Filter Driver
Device Driver
HAL
Device
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5
NT Executive
I/O Manager
File System Driver
Slide 5-64
Slide 5-65
NT Device Drivers
• API model is the same as for a file
• Extend device management by adding
modules to the stream
• Device driver is invoked via an Interrupt
Request Packet (IRP)
– IRP can come from another stream module
– IRP can come from the OS
– Driver must respond to minimum set of IRPs
• See Part I of notes
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 5