Configuring Windows 7 (Training Kit) - Part 24 doc

FIgUre 4-6 Driver details Installing Devices and Managing Device Drivers PnP specifications define how a computer detects and configures newly added hardware and automatically installs t

Viewing Bandwidth Allocations for a USB Host Controller

Each USB controller has a fixed amount of bandwidth that all attached devices share If you

suspect a USB controller requires more bandwidth, you can confirm this by viewing the

bandwidth allocations currently being used by each device In Device Manager, double-click

Universal Serial Bus Controllers, right-click the Host Controller for your system, and choose

Properties On the Advanced tab, in the Bandwidth-Consuming Devices list, view the

bandwidth used by each device

Viewing Device Driver Information

To view details about the device drivers that are running on your computer, navigate to the

device whose driver you are investigating, right-click the device, and choose Properties On

the Driver tab, you can click Update Driver to update the driver, Uninstall to remove it, and

Disable to disable the device If the driver replaced a previously installed driver, the Roll Back

Driver button is also enabled To obtain details about the driver, click Driver Details The

Driver File Details dialog box appears as shown in Figure 4-6, with a list of the individual files

that make up the driver, file version information, and digital signature information

FIgUre 4-6 Driver details

Installing Devices and Managing Device Drivers

PnP specifications define how a computer detects and configures newly added hardware and

automatically installs the device driver Windows 7 supports PnP so that when a user plugs in

a hardware device, the operating system searches for an appropriate device driver package,

automatically configuring it to work without interfering with other devices This makes the

installation straightforward

However, users cannot be permitted to plug any device they please into their work computers Device driver software runs as if it is a part of the operating system with

unrestricted access to the entire computer, and only authorized device drivers can be

permitted

When a user inserts a device, Windows 7 detects the new hardware and the Plug and Play service identifies the device and searches the driver store for a driver package that matches the device If a suitable driver is found, the device is considered to be authorized and the Plug and Play service copies the driver file (or files) from the driver store to its operational location, typically C:\Windows\Sysrem32\Drivers The Plug and Play Service configures the registry and starts the newly installed driver

Installing Device Drivers from Windows Update

By default, updated device drivers uploaded to Windows Update are downloaded and installed automatically on a client computer You can amend this behavior through the Device Installation Settings dialog box, shown in Figure 4-7 The most straightforward method of

accessing this dialog box is to type device installation in the Search text box on the Start

menu and click Change Device Installation Settings

FIgUre 4-7 Device Installation Settings dialog box

The default setting is Yes, Do This Automatically (Recommended) However, if you want

to ensure that only device drivers you have tested are installed on the computers running Windows 7 in your organization, you can select Never Install Driver Software From Windows Update

If you choose Always Install The Best Driver Software From Windows Update, Windows 7 will determine automatically whether a new driver is superior to one already installed However, you will not be able to test the new driver before installation Similarly, if you select Only Install

Driver Software From Windows Update If It Is Not Found On My Computer, you will not be

able to test the new drivers before they are installed In an enterprise environment, particularly

if software is distributed through Windows Server Update Services (WSUS), driver updates from

the Windows Update site are disabled and the site is removed from the search path

Staging a Device Driver

If the device driver does not exist in the driver store, then an administrator needs to approve

the device This process is known as staging You can configure a computer Group Policy so

that ordinary users can approve the installation of a device in a specific device setup class,

and you can stage a specific device driver so ordinary users can install that device However,

it would be most unwise to do this for all devices You learn how to configure Group Policy

to allow non-administrators to install specific devices and device setup classes in the practice

session later in this lesson

Windows 7 starts the staging process by searching for a matching driver package in folders

specified by the DevicePath registry entry You learn how to configure Windows 7 to search

additional folders for device drivers in the practice session later in this lesson If a suitable

driver is not found, Windows 7 searches the Windows Update Web site Finally, the user is

prompted to insert installation media

If a driver is found, the operating system checks that the user has permission to place the

driver package in the driver store The user must have administrator credentials or computer

policy must be set to allow standard users to install the identified device Windows 7 then

checks that the driver package has a valid digital signature If the driver package is unsigned

or signed by a certificate not found in the Trusted Publishers store, Windows 7 prompts the

user for confirmation If the driver is approved by an authorized user, the operating system

places a copy of the driver package in the driver store and installation continues

Windows performs all the required security checks during staging, including the verification

of administrator rights and the validation of digital signatures After a driver package has been

successfully staged, any user that logs on to that computer can install the drivers in the driver

store by simply plugging in the appropriate device There are no prompts, and no special

permissions are required

quick Check

n You have four devices plugged into an unpowered USB hub You have a powered

hub with an empty slot and decide you could improve hardware performance by transferring one device from the first hub to the second How to you determine which of the devices on the unpowered hub consumes the most power?

quick Check answer

n Double-click Universal Serial Bus Controllers, in Device Manager Right-click the

unpowered USB hub and choose Properties On the Power tab, view the power required by each device in the Attached Devices list.

More Info the DrIVer StOre aND the StagINg prOCeSS

For more information about the driver store and the staging process, see http://technet

.microsoft.com/en-us/library/cc754052.aspx This is a Windows Server 2008 and Windows

Vista reference, but it also applies to Windows 7.

Installing a Non-PnP Device

If a device is non-PnP (for example an older device), your logged-in account needs to have administrator credentials for you to install it If the device comes with installation media, Microsoft recommends you insert that media and use the installation software it contains Typically, you do this before you plug in the device

Otherwise, open Device Manager, right-click the computer name at the root of the tree in the details pane, and click Add Legacy Hardware This starts the Add Hardware Wizard shown

in Figure 4-8

FIgUre 4-8 The Add Hardware Wizard

The wizard lets you choose whether to scan and search for hardware or to install hardware you manually select from a list If you choose the former option, the device needs to be attached to the computer The procedure is the same as for staging PnP hardware that has not been preauthorized

If you choose to select hardware from a list, you are presented with a list of device types If you opt to select All Devices, you can select a device by manufacturer as shown

in Figure 4-9 If you have the driver (but not necessarily the driver installation package) on removable media or in a folder on your hard disk, you can click Have Disk

When a driver has been chosen, the wizard installs your hardware If there are problems with the hardware (for example, you get a Code 10 error—the device cannot start), these are listed in the final page of the wizard

FIgUre 4-9 Selecting a device driver

Configuring Device Installation Policies

In the practice later in this lesson, you use Local Group Policy Editor to permit non-administrators

to install devices of a specified device setup class You can also configure other device installation

policies using the same tool In Local Group Policy Editor, expand Computer Configuration;

expand Administrative Templates, System, Device Installation; and click Device Installation

Restrictions In the right pane, click Standard to view the Standard tab This tab contains a list of

policies, as shown in Figure 4-10

FIgUre 4-10 Device installation restriction policies

You can use these policies to perform the following actions:

n Permit members of the Administrators group to install and update the drivers for any device, regardless of other policy settings

n Enable Windows 7 to install or update device drivers whose device setup class globally unique identifiers (GUIDs) you specify, unless another policy setting specifically prevents installation

n Prevent Windows 7 from installing or updating device drivers whose device setup class GUIDs you specify This policy overrides any other policy that permits update

or installation

n Display a custom message to users in the notification balloon when a device

installation is attempted and a policy setting prevents the installation

n Display a custom message title in the notification balloon when a device installation

is attempted and a policy setting prevents the installation

n Specify a list of PnP hardware IDs and compatible IDs for devices that Windows

is allowed to install Other policy settings that prevent device installation take precedence over this policy

n Specify a list of PnP hardware IDs and compatible IDs for devices that Windows

is prevented from installing This policy overrides any other policy that permits installation

n Set the amount of time (in seconds) that the system will wait to reboot to enforce

a change in device installation restriction policies

n Prevent Windows 7 from installing removable devices This policy setting takes precedence over any other policy setting that allows Windows 7 to install a removable device

n Prevent the installation of devices that are not specifically described by any other policy setting

You can open Local Group Policy Editor by entering gpedit.msc in the Start search box It is

highly recommended that you double-click each of the policies in Device Installation Restrictions (and in Device Installation) in turn and obtain more details about each Investigating the policies

in Local Group Policy Editor is one of the suggested practices at the end of this chapter

Working with Device Drivers

You saw previously that installing a hardware device involved locating the device driver installation files and installing the driver Once the driver is installed, you can update it (by installing a replacement driver), uninstall it, disable it, and enable it If you have updated

a driver and find that the updated driver does not work as well as the previous driver, you can roll back to the driver that was installed before the update

If an updated device driver is distributed through Windows Update, it is typically installed automatically if you choose to download it Usually you use the Update Driver functionality

if a new or updated device driver becomes available from a vendor some time before it is published to Windows Update To get the latest version of the driver and test it on your

reference computer running Windows 7, you need to download the driver files from the

vendor’s Web site and then manually update the driver

When you update a driver, the process is similar to the way a driver is installed when

new hardware is added to the computer If the driver is already authorized and in the driver

store, or if an administrator it has staged it, the update process, once started, proceeds

automatically without user intervention Otherwise, you can allow Windows 7 to search for

drivers for the hardware device or you can specify a folder address manually as described in

the previous section, “Installing a PnP Device ” If a driver can be found that is more recent

than that already installed, the administrator is prompted to approve the driver

You can start the driver update process in Device Manager in two ways:

n Right-click the device and choose Update Driver Software

n Double-click the device On the Driver tab, click Update Driver

You can install a new driver or one that has been updated If, however, you consider the

current driver installation might be corrupt, updating a driver will not by itself reinstall the

current driver In this case, you need to uninstall the driver and then go through the process

of installing it again As with updating a driver, you can either right-click the device in Device

Manager and choose Uninstall, or you can double-click the device and click Uninstall on the

Driver tab The Driver tab is shown in Figure 4-11

FIgUre 4-11 The Driver tab

Sometimes, rather than uninstalling and reinstalling a driver, you can solve problems by

disabling it If you have a driver conflict, you probably need to disable one of the drivers or

stop it if it is a non-PnP device

You cannot roll back a driver by right-clicking the device in Device Manager You need

to access the device’s Driver tab Unless a previous driver has been installed, the Roll Back

Driver control is disabled In general, you roll back a driver if you have updated a device driver but the new driver does not work as well as the previous one or causes conflicts with other drivers In this case, the previous driver should still be in the driver store and the process should take place without user prompts (other than clicking Yes to confirm)

If you are investigating problems with a driver, or if you have any other reason for wanting

to know more about it, you can click Driver Details on the Driver tab Driver details for

a network adapter driver are shown in Figure 4-12

FIgUre 4-12 Driver details

Driver details indicate where the working driver file is stored Note that this is not the driver store, which is a protected area It also tells you the file name and type Working driver files operate as if they are part of the operating system and typically have a sys extension Driver installation files have an inf extension Driver details include the provider (typically third party), the file version, the Digital Signer (typically Microsoft), and copyright information It can often be useful to know a file version if you are having problems with a driver and are looking for information on the Internet, such as on Microsoft blogs You might see a message along the lines of, “Version 10 0 5 3 has this problem Uninstall it and install version 10 0 5 2 ”

Resolving Driver Conflicts

Driver conflicts are much less common than they used to be It was common 15 years ago that you connected a printer and your mouse stopped working Almost all modern hardware

is PnP The operating system controls installation, and conflicts typically are avoided However,

no system is perfect, and a conflict could still occur

Typically a conflict occurs when two devices require the same resources, particularly when their interrupt or input/output (I/O) requirements clash You can determine resource usage on the Resources tab of the device Properties dialog box, as shown in Figure 4-13 In most device drivers, Use Automatic Settings is selected and Change Settings is disabled

FIgUre 4-13 The Resources tab

Conflicts between PnP devices are unusual and can be solved temporarily by disabling one

of the devices Updating the driver (if an update is available) or uninstalling and reinstalling

the hardware will probably solve the conflict

Figure 4-14 illustrates a conflict situation in which a non-PnP device uses resources also

used by the motherboard If a conflict involves a non-PnP device, you may need to stop this

device to resolve the problem

FIgUre 4-14 A resource conflict

To stop a non-PnP device, perform the following procedure:

1 Open Device Manager

2 On the View menu, choose Show Hidden Devices

3 Double-click Non-Plug and Play Drivers, right-click the device you want to stop, and choose Properties

4 On the Driver tab shown in Figure 4-15, click Stop and then click OK

FIgUre 4-15 The Driver tab for a non-PNP device

The procedure to restart a device is identical except you click Start instead of Stop You can also change the Startup Type on this tab Note that if the Start button on the Driver tab is unavailable, the driver is already loaded

Using the System Information Tool to Identify Resource Conflicts

If you suspect that a device driver is working incorrectly because of resource conflicts, you can view the I/O and IRQ requirements of each device by using the System Information (Msinfo32) tool Using a single tool is more convenient than accessing the Resources tab of

each individual device You start the Msinfo32 tool by entering msinfo32 in the Start search

box, the Run command box, or the command prompt You do not need to open an elevated command prompt to run Msinfo32 The tool provides general system information, as shown

in Figure 4-16

When you expand Hardware Resources, you can view the Memory, I/O, and IRQ resources used by every device on the computer However, arguably the most useful information for resolving conflicts is obtained by selecting Conflicts/Sharing, as shown in Figure 4-17 If you are having problems with a particular device, you can search for the device by specifying

it in the Find What: box, determining what devices it shares resources with, and identifying possible conflicts