Registry Changes During Driver Installation

Assume that the hardware ID is USB \ vid_aaaa & pid_bbbb \ productname

The system will generate a directory for each field in the Registry HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Enum. For example, if the first field in the ID is USB, a USB subdirectory will be generated under enum, if the second field is vid_aaaa & pid_bbbb, The vid_aaaa & pid_bbbb subdirectory is generated under the USB directory. If the last field is productname, The productname subdirectory is generated under the vid_aaaa & pid_bbbb directory. The information contained in the productname subdirectory is the property of the hardware and the required driver.

After the driver is installed successfully, the directory contains the following fields:

Table 1

Capabilities	Zero X 00000014	REG_DWORD
Class	Media	REG_SZ
Classguid	(Defined in the INF file)	REG_SZ
Compatibleids	USB \ class_ff & subclass_00 & port_00 USB \ class_ff & subclass_00 USB \ class_ff	Reg_multi_sz
Configflags	Zero X 00000000	REG_DWORD
Devicedesc	Mydriverdesc	REG_SZ
Driver	{Guid} \ 0042	REG_SZ
Hardwareid	USB \ vid_aaaa & pid_bbbb & rev_0100 USB \ vid_aaaa & pid_bbbb	Reg_multi_sz
Locationinformation	PIXELA-SHANGHAI	REG_SZ
MFG	Mycompany	REG_SZ
Services	DigitalTV	REG_SZ
Uinumber	Zero X 00000000	REG_DWORD

The hardwareid field, compatibleids field, devicedesc field, locationinformation field, capabilities field, and uinumber field are obtained from hardware after hardware is inserted. They are generally configured in firmware. To recognize the hardware correctly, you must manually add the class, classguid, configflags, driver, MFG, and services fields. The two important fields are the driver field and services field. The driver field contains a string pointing to another directory in the registry.

HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ class \ {guid} \ 0042

The services field points to the directory.

HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ DigitalTV

The HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ class \ {guid} \ 0042 directory contains various information about the driver file. After the driver is correctly installed, the following fields are found in the directory:

Table 2

Devloader	* Ntkern	REG_SZ
Driverdata	1-4-2008	REG_SZ
Driverdatadata	Rjb4bf644ec801	REG_BINARY
Driverdesc	Mydriverdesc	REG_SZ
Driverversion	6.0.0.0	REG_SZ
Infpath	Myinf. inf	REG_SZ
Infsection	DigitalTV. Dev	REG_SZ
Infsectionext	. NT	REG_SZ
Machingdeviceid	USB \ vid_aaaa & pid_bbbb	REG_SZ
Ntmpdriver	Mydriver. sys	REG_SZ
Providername	Mycompany	REG_SZ

Most fields in this table are defined in INF. machingdeviceid specifies the device ID that matches the driver and ntmpdriver specifies the driver file name.

The HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ DigitalTV directory specifies the Windows system service corresponding to the driver. The following fields are entered after the driver is correctly installed:

Table 3

Displayname	Mydrivername	REG_SZ
Errorcontrol	1	REG_DWORD
Group	Base	REG_SZ
ImagePath	System32 \ drivers \ mydriver. sys	REG_EXPAND_SZ
Start	3	REG_DWORD
Tag	0x15	REG_DWORD
Type	1	REG_DWORD

Most of the tables are also defined in INF.

Our hardware has two IDs.

USB \ vid_aaaa & pid_bbbb \ productname and

USB \ vid_aaaa & pid_bbbb \ productname2

Sometimes a board without an eeproom may also have this ID.

USB \ vid_aaaa & pid_cccc \ 5 & 111db94e & 0 & 4

Take the three IDs as an example. The HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Enum \ USB directory contains two directories: vid_aaaa & pid_bbbb and vid_aaaa & pid_cccc, and vid_aaaa & pid_bbbb.

Productname and productname2 directories. Each directory has a series of fields similar to Table 1. vid_aaaa & pid_cccc has 5 & 111db94e & 0 & 4 directories, 5 & 111db94e & 0 & 4 directory also contains fields in table 1. A driver directory and a Services Directory are specified for each table. The Services Directory is generally not changed, but the matchingdeviceid field in the driver directory is associated with the hardware ID, so we need at least two Driver directory items, such

HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ class \ {guid} \ 0042

And

HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ class \ {guid} \ 0044

Matchingdeviceid in 0042 is

USB \ vid_aaaa & pid_bbbb,

Matchingdeviceid in 0044 is

USB \ vid_aaaa & pid_cccc.

Sometimes you also need to configure the interface (which must be configured in our driver; otherwise, DirectShow cannot use sourcefilter). You need to perform operations on some directories under HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ deviceclasses.

Many category guids are listed in the HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ deviceclasses directory,

The main category in this figure has the corresponding guid in the directory.

For example, {FD0A5AF4-B41D-11d2-9C95-00C04F7971E0} represents the hardware source filters directory, the following lists a series of information similar to the hardware ID, when the hardware is inserted to obtain the hardware ID, match the corresponding items in the registry, then, the filter under this item is activated. For example, {51d771c7-c589-4b61-ad46-8c8047987a18} represents a bdacapturefilter. Some parameters are listed in device parameters and are defined in INF. After activation, you canProgramUsing bdacapturefilter.