Chris Cant - Writing Windows WDM Device Drivers

• The driver executable must have an 8.3 filename in Windows 98.

• Windows will not use the INF file if it contains invalid section details.

• Section names must be 28 characters or less to work in W98.

If you want to install a driver that is required in the text-mode setup phase of W2000 installation, you must provide a txtsetup.oem file on a floppy disk. See the DDK for details.

An INF file contains all the necessary information to install a WDM device driver, including a list of the files to copy, the registry entries to make, etc.

Windows provides a standard installer for most classes of device and a default installer. The default class installer processes INF files in the manner described in the rest of this chapter. Installers for other classes of device may perform some additional installation steps.

An INF file is a text file that looks like an old INI file. It is made up of sections, each starting with a line with the section name in square brackets (e.g., [Version]). The section contents follow. Each line either has a simple entry (e.g., entry) or sets a value (e.g., entry=value). Sections can be in any order. The order of lines in a section is sometimes important. Comments can be added after a semicolon character. Section and entry names are not case sensitive. A backslash at the end of a line in a section indicates that the line continues onto the next. Double-quotes are used to ensure the correct interpretation of characters (e.g., a backslash in a filename or leading or trailing spaces in strings). INF files can be in Unicode or plain ANSI characters. In some sections, you can opt to include other INF files needed for the installation.

If you need to customize the installation process, consider writing a class installer or — for Windows 2000 — a class coinstaller or a device coinstaller. A class installer takes over the installation of a whole class of devices; it can choose which installation jobs it handles and which it leaves to the default class installer. A coinstaller helps an existing class installer to do its job. A class coinstaller helps install all new devices of a particular class, while a device coinstaller helps just the installation of the device currently being installed. Coinstallers should not interact with the user. Please see the W2000 DDK for details of how to write these DLLs.

Table 11.1 shows the typical sections of an INF file. Sections that you must name are given in italics. The DDK has full details of these sections and the other ones that you can include. Most section names may also exist in a decorated form, as described in the following text. For example, Strings.LangIdSubLangId indicates a locale and SectionName.NT indicates a platform.

The Version section is usually placed at the start of the INF file. Any of the given values for Signature work for both Windows 98 and Windows 2000. See later for details of how to write cross-platform INF files for both Windows 98 and Windows 2000.

Once your driver has passed the Microsoft Hardware Compatibility Tests, you should include a reference to your digital signature file in the CatalogFile entry.

Table 11.1 Typical sections for an INF file

The Strings section defines strings that are substituted wherever else they are used. For example, if the Strings section looks like this:

[Strings]

Msft="Microsoft"

Any instance elsewhere of %Msft% is replaced with Microsoft. Strings are particularly useful for representing GUIDs, but can be used for any type of string, even bit values.

You can internationalize your INF file using strings in two ways. One way is to create a base INF file without any strings in an .inx file, and have a separate .txt file for each locale with the appropriate Strings section. Alternatively, have a common INF file but different Strings sections for each locale, appending .LangIDSubLangID to detail which language and sublanguage applies to this section. LangID and SubLangID are both two digits, as defined in winnt.h. SubLangID 00 is a neutral sublanguage. The following example shows how a different string is defined for UK English.

[Strings]

PrinterName="Abc Color printer"

[Strings.0902]

PrinterName="Abc Colour printer"

The sections in an INF file are arranged in a hierarchy. Table 11.2 shows that the Version, Strings, SourceDisksNames, SourceDisksFiles, and DestinationDirs sections are at the top level.