UEFI / Framework Special Topic Slide 1 UEFI Drivers UEFI / Framework Special Topic Copyright © 2007...

UEFI / Framework Special TopicUEFI / Framework Special Topic Slide 1

UEFI Drivers

UEFI / Framework Special Topic

Copyright © 2007 Intel Corporation


UEFI Driver Model• Used for devices on industry standard buses

– “boot devices”• Structured model of device/bus hierarchy

– Device Drivers and Bus Drivers– Device Drivers are topology agnostic

• Benefits– Simpler Device Drivers

• Moves complexity into Bus Drivers and core services• Smaller driver footprint

– Deterministic driver selection by the platform• Which driver controls which device

– Describes complex bus hierarchies• Embedded, Desktop, Workstation, Server

– Extensible to future bus types

Use of multilayer modularity meansUse of multilayer modularity meansmore scenarios “just work”more scenarios “just work”


UEFI Driver Model• Supports complex bus hierarchies

– Follows the organization of physical/electrical architecture of the machine

• Driver Binding Protocol provides flexibility– Function to match drivers to devices– Driver version management– Hot-plug and unload support

• Drivers not tied to FLASH– Can be loaded from UEFI System Partition

• Extensible– Able to extend to future bus and device types

UEFI Drivers


UEFI Driver Design• Modular chunks of code run in pre-boot

– Manage devices or services– …they are NOT OS-present drivers!

• Drivers export protocol interfaces– Protocol = instance data + access methods– Like C++ classes but more code space efficient– Identified by GUID to avoid collisions– Version numbers and signatures provide means to

manage driver management policy• Drivers may consume protocol interfaces

– Self-describing dependencies– E.g. Memory initialization may depend on SMBUS service


Driver Design Steps

1. Determine Driver Type2. Identify Consumed I/O Protocols3. Identify Produced I/O Protocols4. Identify UEFI Driver Model Protocols5. Identify Additional Driver Features6. Identify Target Platforms

– x86– x64– Itanium Processor Family– EFI Byte Code (EBC)

UEFI Drivers


Complex System Example

• Manageable by UEFI Driver Model

CPUCPU

NorthNorthBridgeBridge

CPUCPU

PCI-IBAPCI-IBABridgeBridge

USBUSB

VGAVGA

PCI-ISAPCI-ISABridgeBridge

IBA-PCIIBA-PCIBridgeBridge

KBDKBD

MouseMouse

RemovableRemovableMediaMedia

(floppy)(floppy)

SCSISCSI

Hard Hard DriveDrive




PCI BUSPCI BUS

IBA BUSIBA BUSPCI BUSPCI BUS

USB BUSUSB BUS

ISA BUSISA BUS

UEFI Drivers

See § 2.5 UEFI 2.1 Spec.


What Type of Driver is Being Designed?

UEFI Images

Applications

DriversService Drivers

OS Loaders

Initializing Drivers

Root Bridge Drivers

UEFI Driver Model

BusDrivers

Device Drivers

UEFI Drivers

Device DriversBus

DriversHybrid Drivers


• Consumes Bus I/O Abstraction(s)• Initializes Device Controller• Produces Device Abstraction(s)

– Block I/O Protocol– Simple Text Output Protocol– Simple Network Protocol

• Does Not Create Any Child Handles• Can still be a “Parent” Controller

Device Driver


Device Drivers

• Manages a Controller or Peripheral Device• Start() Does Not Create Any Child Handles• Start() Produces One or More I/O Protocols

– Installed onto the Device’s Controller HandleExamples:Examples:

PCI Video AdaptersPCI Video AdaptersUSB Host ControllersUSB Host ControllersUSB Keyboards / USB MiceUSB Keyboards / USB MicePS/2 Keyboards / PS/2 MicePS/2 Keyboards / PS/2 Mice

UEFI DriversDrivers

Service Drivers


Root Bridge Drivers

UEFI Driver Model

Device Drivers

Bus Drivers

Hybrid Drivers


• Consumes Parent Bus I/O Abstraction(s)• Initializes Bus Controller• Allocates Resources for Child Controllers• Creates Handles for Child Controllers• Loads drivers from Option ROMs if present

Child Controller HandleEFI_DEVICE_PATH_PROTOCOL

EFI_XYZ_I/O_PROTOCOL

Bus Driver

EFI_BUS_SPECIFIC_DRIVER_OVERRIDE_PROTOCO

Optional


Bus Drivers

• Manages and Enumerates a Bus Controller• Start() Creates One or More Child Handles• Start() Produces Bus Specific I/O Protocols

– Installed onto the Bus’s Child HandlesExamples:Examples:

PCI Network Interface ControllersPCI Network Interface ControllersSerial UART ControllersSerial UART Controllers



Root Bridge Drivers

UEFI Driver Model

Device Drivers

Bus Drivers

Hybrid Drivers

UEFI Drivers


Hybrid Drivers

• Manages and Enumerates a Bus Controller• Start() Creates One or More Child Handles• Start() Produces Bus Specific I/O Protocols

– Installed onto the Bus’s Controller Handle– Installed onto Bus’s Child Handles

Examples:Examples:PCI SCSI Host ControllersPCI SCSI Host ControllersPCI Fiber Channel ControllersPCI Fiber Channel Controllers



Root Bridge Drivers

UEFI Driver Model

Device Drivers

Bus Drivers

Hybrid Drivers

UEFI Drivers


Service Drivers

• Does Not Manage Hardware • Provides Services to other Drivers• Does not support Driver Binding Protocol• Typically installs protocols in driver entry point• Creates One or More Service Handles• Produces Service Specific Protocols

– Installed onto Service HandlesExamples:Examples:

UEFI Decompress ProtocolUEFI Decompress ProtocolUEFI Byte Code Virtual MachineUEFI Byte Code Virtual MachineBoot Integrity Services (BIS)Boot Integrity Services (BIS)



Root Bridge Drivers

UEFI Driver Model

Device Drivers

Bus Drivers

Hybrid Drivers

UEFI Drivers


Driver Initialization

• EFI Driver Handoff State• Not Allowed to Touch Hardware Resources• Installs Driver Binding on Driver Image Handle

Installed by LoadImage()

Installed in Driver InitializationImplemented by Driver Writer

Created by LoadImage() Driver Image HandleEFI_LOADED_IMAGE

EFI_DRIVER_BINDING

Registers Driver for Later UseRegisters Driver for Later Use



• Typically Touches Hardware• Performs One Time Initialization Operations• Does Not Create Any Handles• Does Not Produce Any Protocols• Unloaded When Finished

Examples: NoneExamples: None



Root Bridge Drivers

UEFI Driver Model

Device Drivers

Bus Drivers

Hybrid Drivers

UEFI Drivers


Root Bridge Drivers

• Typically Manages Part of Core Chipset• Directly Touches Hardware• Creates One or More Root Bridge Handles• Produces Root Bridge I/O Protocols

– Installed onto new Root a Bridge Handles

Examples: PCI Host BridgeExamples: PCI Host Bridge



Root Bridge Drivers

UEFI Driver Model

Device Drivers

Bus Drivers

Hybrid Drivers

UEFI Drivers


What I/O Protocols are Consumed?• PCI Adapters

– PCI I/O Protocol– Device Path Protocol

• USB Peripherals– USB I/O Protocol– Device Path Protocol

FLASH

UEFI Drivers


What I/O Protocols are Produced?

SCSISCSI RAIDFiber Channel

• SCSI Pass Thru Protocoland

• Block I/O Protocol

FLASH

UEFI Drivers


What I/O Protocols are Produced?

Network Interface Controller (NIC)

• Universal Network Driver Interface (UNDI)and

• Network Interface Identifier Protocol (NII)

FLASH

UEFI Drivers


Driver Image HandleEFI_LOADED_IMAGE_PROTOCOL

Responsibilities of Driver Writer

EFI_DRIVER_BINDING_PROTOCOLSupported()Start()Stop()Version

• Driver Image Handle Required Protocols

Installed by the core

Installed by the driver

Unload()Published by the driver

UEFI Drivers

EFI_LOADED_IMAGE_PROTOCOL

See § 2.5.2 UEFI 2.1 Spec.


MoreResponsibilities of Driver Writer

Driver Image HandleEFI_DRIVER_CONFIGURATION_PROTOCOL

SetOptions()OptionValid()ForceDefaults()SupportedLanguages

EFI_DRIVER_DIAGNOSTICS_PROTOCOLRunDiagnostics()SupportedLanguages

• Driver Image Handle Optional Protocols

EFI_COMPONENT_NAME_PROTOCOLGetDriverName()GetControllerName()SupportedLanguages

UEFI Drivers


Driver Design Checklist

Driver Type

I/O Protocols Consumed

I/O Protocols Produced

Driver Binding

Component Name

Driver Configuration

Driver Diagnostics

Unloadable

Exit Boot Services Event

Runtime

Set Virtual Address Map Event

UGA DrawUGA I/O

SCSI Pass ThruBlock I/O

PCI I/O PCI I/ODevice Path

BusDevice Hybrid

PCINIC

PCI Video

PCIRAID

PCI I/ODevice Path

UNDI, NII

UEFI Drivers


• ConnectController()– Called from Boot Manager or during load– Precedence rules are applied

• Context override• Platform override• Bus override• Version number

– Order of which drivers are installed into handle database is not deterministic

• DisconnectController()– Must test and implement Stop()

Running UEFI driversUEFI Drivers


Implement, Test & Debug• See Backup Slides for Details

– Required for IHVs– Optional for OEM/ODMs

• Test Functions with EFI Shell Commands• Check for Leaks with EFI Shell Commands• Install UEFI Compliant Operating System• Boot UEFI Compliant Operating System• Debug Macros Identify Critical Failures• Use Same Techniques on all CPU Types

– x86, x64, Itanium Processor Family, EBC

UEFI Drivers


Driver Guidelines

• Don’t touch hardware in Driver Entry• Keep Supported() small and simple• Move complex I/O into Start() and Stop()• Start() / Stop() mirror each other

– InstallProtocolInterface() UninstallProtocolInterface()– OpenProtocol() CloseProtocol– AllocatePages()FreePages()– AllocatePool() FreePool()

• Driver Entry / Unload() mirror each other

Driver Guidelines


PCI Device Drivers

• Always Call PciIo->Attributes()– Advertises Dual Address Cycle Capability– Save and Enable Attributes in Start()– Disable Attributes in Stop()

• DMA – Bus Master Write Operations– Must call PciIo->Flush()

• DMA – Setting Up with PciIo->Map()– Do Not Use Returned DeviceAddress– Not all chipsets have 1:1 bus/system mappings

Driver Guidelines


PCI Device Drivers – Start()Status = PciIo->Attributes( PciIo, EfiPciIoAttributeOperationGet, 0, &ControllerContext->OriginalPciIoAttributes );if (EFI_ERROR (Status)) { // Error Handling}Status = PciIo->Attributes( PciIo, EfiPciIoAttributeOperationEnable, (EFI_PCI_IO_ATTRIBUTE_IO | EFI_PCI_IO_ATTRIBUTE_MEMORY | EFI_PCI_IO_ATTRIBUTE_BUS_MASTER | EFI_PCI_IO_ATTRIBUTE_DUAL_ADDRESS_CYCLE), 0, NULL );if (EFI_ERROR (Status)) { // Error Handling}

Save Original and EnableSave Original and Enable

Driver Guidelines


PCI Device Drivers – Stop()Status = PciIo->Attributes( PciIo, EfiPciIoAttributeOperationSet, &ControllerContext->OriginalPciIoAttributes NULL );if (EFI_ERROR (Status)) { // Error Handling}

Restore OriginalRestore Original

Driver Guidelines


Preventing Alignment FaultsVOIDScsiDeviceNodeInit ( IN OUT SCSI_DEVICE_PATH *ScsiDeviceNode, IN UINT16 Pun, IN UINT16 Lun ){ ScsiDeviceNode->Scsi.Header.Type = MESSAGING_DEVICE_PATH; ScsiDeviceNode->Scsi.Header.SubType = MSG_SCSI_DP; SetDevicePathNodeLength (&ScsiDeviceNode->Scsi.Header, sizeof(SCSI_DEVICE_PATH)); ScsiDeviceNode->Scsi.Pun = Pun; ScsiDeviceNode->Scsi.Lun = Lun;}

BAD

ScsiDeviceNode may not be alignedScsiDeviceNode may not be aligned

Driver Guidelines


Preventing Alignment FaultsVOIDScsiDeviceNodeInit ( IN OUT SCSI_DEVICE_PATH *ScsiDeviceNode, IN UINT16 Pun, IN UINT16 Lun ){ SCSI_DEVICE_PATH MyDeviceNode;

MyDeviceNode.Scsi.Header.Type = MESSAGING_DEVICE_PATH; MyDeviceNode.Scsi.Header.SubType = MSG_SCSI_DP; SetDevicePathNodeLength (&MyDeviceNode.Scsi.Header, sizeof(SCSI_DEVICE_PATH)); MyDeviceNode.Scsi.Pun = Pun; MyDeviceNode.Scsi.Lun = Lun;

gBS->CopyMem (ScsiDeviceNode, &MyDeviceNode, sizeof(SCSI_DEVICE_PATH));}

GOOD

gBS->CopyMem() handles all alignmentsgBS->CopyMem() handles all alignmentsMyDeviceNode is alignedMyDeviceNode is aligned

Driver Guidelines


Use UEFI Driver Library Functions

CHILD_DEVICE Child;

Child = EfiLibAllocateZeroPool (sizeof (CHILD_DEVICE));if (Child == NULL) { return EFI_OUT_OF_RESOURCES;}

Library Functions Simplify Source CodeLibrary Functions Simplify Source CodeLibrary Functions May Reduce SizeLibrary Functions May Reduce Size

CHILD_DEVICE Child;

Status = gBS->AllocatePool ( EfiBootServicesData, sizeof (CHILD_DEVICE), &Child );if (EFI_ERROR (Status)) { return Status;}gBS->SetMem (Child, sizeof (CHILD_DEVICE), 0);

OK

GOOD

Driver Guidelines


UEFI Device Paths

• EFI_DRIVER_BINDING.Start()Child->DevicePath = EfiAppendDevicePathNode ( ControllerDevicePath, ChildDevicePathNode );if (Child->DevicePath == NULL) { return(EFI_OUT_OF_RESOURCES);}

gBS->FreePool (Child->DevicePath);

• EFI_DRIVER_BINDING.Stop()

Parent Device Path is OpaqueParent Device Path is OpaqueNot Parsed by Bus DriversNot Parsed by Bus Drivers

Driver Guidelines


Bus Walk Tips

• Use LocateHandleBuffer(Bus I/O Protocol)– Do not scan PCI configuration space

• Implement support for RemainingDevicePath – Highly recommended for all bus drivers

• (i.e. SCSI, Fibre Channel, etc.)– Allows bus driver to bypass full enumeration.– Reduces boot time

Driver Guidelines


Component Name Protocol

• Limit Lengths of Names to 40 Unicode Characters• Include Driver Name and Version Number• UNDI Driver (Network Interface Controller)

– Typically the Name of the PCI Controller

• MAC Node Produced by an UNDI Driver– Identify Location of Physical Connector on NIC

• PCI Slots– Identify Physical Location of PCI Slots in the System

• SCSI / SCSI RAID / Fiber Channel– Controller - Typically name of the PCI Controller– Channel - Identify Physical Location of the SCSI Channel– Disk - Use Results from INQUIRY Command

Driver Guidelines


Option ROM Size Reduction

• Use UEFI Compression• Compile with EFI Byte Code Compiler

– Single Binary for x86, x64 and Itanium– Smaller than Itanium Binaries– Comparable to x86 Binaries– Compresses Well ~ 50%

Driver Guidelines


How To Improve Portability

1. Do Not Assume Max Number of Children2. Do Not Use Fixed Memory Addresses3. Do Not Use Assembly4. Do Not Use Floating Point Arithmetic5. Some Minor EBC Porting Considerations6. Bus Drivers Should Support Producing 1

Child at a time if possible (improves boot performance)

Driver Guidelines Improve PortabilityDriver Guidelines Improve Portability

Driver Guidelines


UEFI Driver Writer’s Guide

• Captures Practical Experiences• Use as a Recipe Book• Must Read for all UEFI Driver Developers• Living Document

– Content Based on Industry Feedback– Updated as Techniques are Refined– Updated as New Technologies are Introduced

EFI 1.10Driver Writer’s Guide

Draft for Review

Version 0.9July 20, 2004

Driver Writer’s Guide


General Topics• Overview of UEFI Concepts• UEFI Services

– Commonly Used by UEFI Drivers– Rarely Used by UEFI Drivers– Should Not Be Used by UEFI Drivers

• General Driver Design Guidelines• Classes of UEFI Drivers• Driver Entry Point• Private Context Data Structures• UEFI Driver Model Protocols



Platform Specific Topics

• PCI Driver Guidelines• USB Driver Design Guidelines• SCSI Driver Design Guidelines• Size Optimizations• Speed Optimizations• Itanium Processor Family Considerations• EFI Byte Code Considerations• Building/Testing/Debugging UEFI Drivers



Benefits of following EFIDriver Guidelines

• Following EFI Driver Guidelines– Improves Portability, Quality, and Interoperability– Reduces Implementation Effort– May Increase Performance– May Reduce FLASH Overhead

EFI Driver Writer’s Guide Helps EFI Driver Writer’s Guide Helps Improve EFI DriversImprove EFI Drivers



Summary

• Good Designs Save Time and Money• Many Tools Available to Test and Debug• Using Driver Guidelines Improves Portability• Compile in EBC to have one driver image to

support x86, x64 and Itanium.

UEFI / Framework Special Topic Slide 1 UEFI Drivers UEFI / Framework Special Topic Copyright © 2007...

Documents

Transcript of UEFI / Framework Special Topic Slide 1 UEFI Drivers UEFI / Framework Special Topic Copyright © 2007...