Como o Windows usa arquivos .inf para carregar os drivers corretos

Question

O que acontece quando um dispositivo de hardware corresponde a dois ou mais arquivos inf quando o Windows está carregando os drivers para esses dispositivos?

Por exemplo, a unidade de disco no meu PC tem dois drivers carregados para ela, cdrom.sys e iaStorF.sys. O cdrom.sys foi carregado a partir do arquivo cdrom.inf e o iaStorF.sys foi carregado a partir do arquivo oem2.inf que eu instalei da Intel.

O Windows pesquisa todos os arquivos inf e carrega qualquer coisa que corresponda?

Se sim, qual é o 'arquivo INF principal', o que quero dizer com isso no Gerenciador de Dispositivos quando eu clico na unidade de disco e vou para a aba 'Detalhes', e então vejo o nome inf, ele mostra cdrom.inf arquivo, mesmo que também corresponda oem2.inf.

Se eu olhar para o meu monitor, que também tem dois drivers para ele carregados de dois arquivos inf, oem22.inf e monitor.inf. Em 'Detalhes' e nome inf, mostra oem22.inf.

Por que ele escolheu oem22.inf em monitor.inf?

    

Answer 1

Na verdade, é um dos principais drivers. O outro que você vê é um driver de filtro - iaStorF.sys, onde F significa filtro.

Um driver de filtro é um driver do Microsoft Windows que estende ou modifica a função de dispositivos periféricos ou suporta um dispositivo especializado no computador pessoal. É um driver ou programa ou módulo que é inserido na pilha de drivers existente para executar alguma função específica. ( wikipedia )

Aqui está uma captura de tela do meu sistema, para unidades de disco, está em

HKLM\System\CurrentControlSet\Control\Class\{4D36E967-E325-11CE-BFC1-08002BE10318}

Odriverprincipalédisk.sys,osoutros3sãotodososdriversdefiltro,EhStoreClass.sysepartmgr.syssãoosdriverspadrãodoMSnoWindows8,edevmon.sysédeeset.

Paramonitores,oadicionalinféopcional,usadoparaestenderacapacidade,comoperfildecor(.icm)ouinformaçõesEDID,essasinfnãosãonecessáriasparaomonitoroperar,somenteomonitor.sysénecessário.( MSDN )

Mais algumas informações sobre o driver de filtro, reproduzi-lo-ei aqui para referência futura ( MSDN )

Filter drivers are optional drivers that add value to or modify the behavior of a device. A filter driver can service one or more devices. Bus Filter Drivers

Bus filter drivers typically add value to a bus and are supplied by Microsoft or a system OEM (see the Possible Driver Layers figure). Bus filter drivers are optional. There can be any number of bus filter drivers for a bus.

A bus filter driver could, for example, implement proprietary enhancements to standard bus hardware.

For devices described by an ACPI BIOS, the power manager inserts a Microsoft-supplied ACPI filter (bus filter driver) above the bus driver for each such device. The ACPI filter carries out device power policy and powers on and off devices. The ACPI filter is transparent to other drivers and is not present on non-ACPI machines. Lower-Level Filter Drivers

Lower-level filter drivers typically modify the behavior of device hardware (see the Possible Driver Layers figure). They are typically supplied by IHVs and are optional. There can be any number of lower-level filter drivers for a device.

A lower-level device filter driver monitors and/or modifies I/O requests to a particular device. Typically, such filters redefine hardware behavior to match expected specifications.

A lower-level class filter driver monitors and/or modifies I/O requests for a class of devices. For example, a lower-level class filter driver for mouse devices could provide acceleration, performing a nonlinear conversion of mouse movement data. Upper-Level Filter Drivers

Upper-level filter drivers typically provide added-value features for a device (see the Possible Driver Layers figure). Such drivers are usually provided by IHVs and are optional. There can be any number of upper-level filter drivers for a device.

An upper-level device filter driver adds value for a particular device. For example, an upper-level device filter driver for a keyboard could enforce additional security checks.

An upper-level class filter driver adds value for all devices of a particular class.

    

Answer 2

Algumas informações podem ser encontradas neste artigo antigo da Microsoft (horário do XP) Como o Windows determina o mais adequado driver de dispositivo para instalar durante a instalação :

When you run Windows Setup, you may have more than one set of device drivers or .inf files that work with a particular device. Both Setup and Plug and Play attempt to resolve these conflicts by selecting the device driver that is the most suitable match for the device that is being installed.

Plug and Play can search all the .inf files for the most suitable device driver to install for a particular device. Plug and Play does not stop its search on the first match that Plug and Play finds. Plug and Play continues to search all the .inf files that are listed in the search path of Plug and Play, as defined in the following registry entry:

HKEY-LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion

DevicePath:Reg_Expand_SZ:%Systemroot%\Inf

Setup builds a list of compatible device drivers that contained a match in an .inf file and assigns a "rank" for each one that had been located. The rank can range from "0" to "0xFFFF" with 0 being the most suitable possible match and 0xFFFF the worst possible match. The device driver with the lowest rank is considered the most suitable possible match and is the device driver installed.

However, if two device drivers have the same lowest rank, Setup uses the device driver with the most recent date. If one of the device drivers is signed and the other device driver is unsigned, the unsigned device driver date is assigned a value of 0xFFFFFFFF, and the signed device driver is selected and installed.

Deve-se observar que, por padrão, uma versão de 64 bits do Windows não aceita drivers não assinados como candidatos. Isso só é possível no Windows de 32 bits.

O artigo a seguir contém o algoritmo mais recente: Como o Windows classifica os drivers

Windows assigns a rank to a driver that matches a device. The rank indicates how well the driver matches the device. A driver rank is represented by an integer that is equal to or greater than zero. The lower the rank, the better a match the driver is for the device.

The rank of a driver is a composite value that depends on how a driver is signed, the features that are supported by the driver, and the type of match between the device identification strings that are reported by a device and the device identification strings that are specified in the entries of an INF Models section of a driver INF file.

A rank is represented by a value of type DWORD. A rank is sum of a signature score, a feature score, and an identifier score. A rank is formatted as 0xSSGGTHHH, where S, G, T, and H are four-bitfields and the SS, GG, and THHH fields represent the three ranking scores, as follows:

• The signature score ranks a driver according to how a driver is signed. The signature score depends only on the value of the SS field. An unspecified signature score is represented as 0xSS0000000.

For an overview on how Windows Vista and later versions of Windows use a driver's signature to determine how the driver is installed, see Signature Categories and Driver Installation.

Basicamente, as assinaturas digitais de uma autoridade de assinatura do Windows obtêm a pontuação mais alta.

• The feature score ranks a driver based on the features that the driver supports. The feature score depends only on the value of the GG field. An unspecified feature score is represented as 0x00GG0000.

Esta informação é especificada dentro do arquivo .inf, então um fabricante pode pedir seus próprios drivers.

• The identifier score ranks a driver based on the type of match between a device identification string that is reported by a device and a device identification string that is listed in an entry of an INF Models section of a driver INF file. The identifier score depends only on the value of the THHH field. An unspecified identifier score is represented as 0x0000THHH.

Este texto é bastante confuso e confuso. Veja o link para uma descrição muito melhor para pontuação do identificador.