UEFI与固件程序设计
Tel：69589584
Email:wang.box@163.com
同济大学软件学院
Agenda
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Overview
DXE Core
DXE Dispatcher
DXE Architectural Protocol
DXE Services
DXE Drivers
Boot Flow
DXE IPL
DXE MAIN
Exposed
Platform
Interface
verify
Pre
Verifier
CPU
Init
Chipset
Init
Transient OS
Environment
Device,
Bus, or
Service
Driver
Board
Init
EFI Driver
Dispatcher
Transient OS
Boot Loader
Power on
Pre EFI
Initialization
(PEI)
Driver
Execution
Environment
(DXE)
[ . . Platform initialization . . ]
OS-Present
App
Boot
Manager
Intrinsic
Services
security
Security
(SEC)
OS-Absent
App
Boot Dev
Select
(BDS)
Final OS
Boot Loader
Final OS
Environment
?
Transient
System Load
(TSL)
Run Time
(RT)
After
Life
(AL)
[ . . . . OS boot . . . . ]
Shutdown
Why DXE
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No DXE
– BIOS features coded in proprietary fashion
 ODM has to port features from IBV to IBV
 Third parties can not provide value added pre OS features
– Single source file controls boot flow
With DXE
– Works like OS, large group of companies can write drivers
– Modular systems enabled
 FLASH on a plug in module to support module
Properties of DXE
Foundation
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Depends only on HOB list
– State initialization passed in from PEI
No hard coded addresses in DXE
– Foundation code can be loaded anywhere
No hardware specifics in DXE Foundation
– Access to hardware abstracted by a set of architectural
protocols (APs)
– APs implemented as drivers
– Only DXE Foundation may call APs
– APs encapsulate CPU, chipset, board specifics
DXE Components
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DXE Core – The main DXE executable binary responsible for dispatching
drivers and provide basic services.
DXE Driver – code loaded by the core to do various initializations,
produce protocols and other services.
DXE Dispatcher – The part of the DXE core that searches for and
executes the drivers in the correct order.
DXE Architectural Protocols – Produced by DXE drivers to abstract DXE
from hardware.
UEFI System Table – Contains pointers to all the EFI service tables,
configuration tables, handle database, and console device.
Agenda
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Overview
DXE Core
DXE Dispatcher
DXE Architectural Protocol
DXE Services
DXE Drivers
DXE Core
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No hard coded addresses allowed
Single Binary for each CPU Architecture
Well specified and validated
Written in C. No assembly allowed
Consumes
 HOB List
 Architectural Protocols
Produces
 Dispatcher
 EFI Boot Services
 EFI Runtime Services
DXE Core Block Diagram
System
System
Memory
Memory
System
I/O
Memory
Resources
System
MMIO
Memory
Resources
System
Firmware
Memory
Devices
System
Firmware
Memory
Volumes
System
DXE
Memory
Drivers
HOB List
PHIT
HOB
HOB
HOB
EFI Boot Services Table
HOB
HOB
DXE Services
...
System
DXE
Memory
Drivers
HOB
EFI System Table
EFI Runtime Services Table
DXE Core / DXE Dispatcher
Security
Architectural
Protocol
CPU
Architectural
Protocol
Metronome
Architectural
Protocol
Timer
Architectural
Protocol
BDS
Architectural
Protocol
Runtime
Architectural
Protocol
Watchdog
Timer
Architectural
Protocol
Hardware
Variable
Architectural
Protocol
Monotonic
Counter
Architectural
Protocol
Reset
Architectural
Protocol
Status Code
Architectural
Protocol
Real Time
Clock
Architectural
Protocol
DXE Core Functional Blocks
DXE Core
EFI Boot Services
DXE Services
Task Priority
Services
Event and Timer
Services
Image
Services
Global Coherency Domain
Services
Memory
Services
Protocol Handler
Services
Driver Support
Services
Dispatcher Services
Firmware Volume Driver
PE/COFF
HOB
Loader
Parser
DXE Dispatcher
Firmware
Volume
Block Driver
Section
Extraction
Protocol
Driver
Flush Instruction
Cache
(Read-Only)
(Memory
Mapped)
Decompress
Driver
Switch
SetJump
Stacks
LongJump
Dependency Expression
Evaluator
DXE Core Data Structures
Active Consoles
Input Console
UEFI
System
Table
UEFI Runtime Services Table
Variable Services
Output Console
Real Time Clock Services
Standard Error Console
Reset Services
Status Code Services
UEFI Boot Services Table
Virtual Memory Services
Task Priority Level Services
Memory Services
Version Information
Event and Timer Services
UEFI Specification Version
Protocol Handler Services
Firmware Vendor
Image Services
Firmware Revision
Driver Support Services
System Configuration Table
DXE Services Table
Global Coherency Domain Services
Dispatcher Services
DXE Services Table
HOB List
ACPI Table
SMBIOS Table
Handle Database
Protocol Interface
Protocol Interface
Protocol Interface
Protocol Interface
Protocol Interface
Protocol Interface
…
SAL System Table
Boot Services and Structures
Runtime Services and Structures
Only available prior to OS runtime
Available before and during OS runtime
DXE Main
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Responsible for Initializing DXE Core
Consumes HOB List
Builds EFI System Table
Builds EFI Boot Services Table
Builds EFI Runtime Services Table
Builds DXE Services Table
Makes Memory-Only Boot Services Available
Hands off control to the DXE Dispatcher
 Requires access to Firmware Volumes
 Requires LoadImage(), StartImage(), Exit()
 May require decompression service
DXE Core Initialization
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Initialize EFI Boot Services Table
 Global Variable in DXE Core
 All services return EFI_NOT_AVAILABLE_YET
Initialize DXE Services Table
 Global Variable in DXE Core
 All services return EFI_NOT_AVAILABLE_YET
Initialize Memory-Only TPL Services
 RaiseTPL(), RestoreTPL()
Initialize Memory Services (Parses HOB List)
 AllocatePages(), AllocatePool(), FreePages(), FreePool()
Allocate EFI System Table
 Allocated from EfiRuntimeServicesData
Allocate EFI Runtime Service Table
 Allocated from EfiRuntimeServicesData
 All services return EFI_NOT_AVAILABLE_YET
DXE Core Initialization
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Initialize GCD Services (Parses HOB List)
Initialize Driver Support Services
Initialize Event Services
Initialize Protocol Services
Initialize Miscellaneous Services
Add HOB List to System Configuration Table
 Part of EFI System Table
 Provides other component access to HOB List
Initialize Image Services
 Creates Image Handle for DXE Core itself
DXE Core Initialization
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Create event for each Architectural Protocol
 Informs DXE Core when AP is installed
 Used to complete EFI Boot Services
 Used to complete EFI Runtime Services
Initialize Firmware Volume Drivers
 Provides file access to FVs discovered by PEI
Initialize File Decompression (Optional)
Hand control to DXE Dispatcher
Agenda
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Overview
DXE Core
DXE Dispatcher
DXE Architectural Protocol
DXE Services
DXE Drivers
Dispatcher Goals
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Resolve Execution Ordering Among DXE Drivers
 Drivers may be written by different organizations
 Different divisions
 Different companies
Support Known Business Issues
 Emergency patches
 “Control of Destiny” for
 System developer
 Add-in card developer
 Driver developer
Expansion Hooks for e.g. Security
DXE Dispatcher Model

Some of each
 A Priori list of drivers to be run first
 Defined by system developers
 May be null
 Generally implemented as pre-load dispatch queue
 Requirements based dispatching for the rest
 General Concept: Driver provides a list of requirements that
must be met before it can be dispatched.
 A syntax that gets the ordering to about 90% is ok
 EFI primitives exist to do finer granularity ordering
Requirements
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Protocols are the “Requirements”
 Represented by their GUIDs
 The fundamental primitive is
 “Does this protocol exist?”
 Hits the 90% target
 Driver may have to do RequestProtocolNotify for finer granularity
“List of Requirements”: Boolean Expressions
 Operators: And, Or, Not (&, |, !)
 Special operators: Before, After
 Run this driver just before or just after that one
 Used for patching
 Internally, stored in driver header as Postfix (RPN) for quicker
processing
 Tool support planned
Driver Execution Environment
DXE Foundation Dispatcher
Handle Database
1
Loaded Image
Protocol
Main Firmware
Volume
DXE Dispatcher
Driver C
Dependent:
A
B
C
Scheduled:
Driver B
Initializing:
(CPU_AP)
Initialized:
Driver A
Dependency Expression:
CPU_AP
Evaluates To:
FALSE
(Timer_AP)
DXE
Foundation
Driver Execution Environment
DXE Foundation Dispatcher
Handle Database
1
Loaded Image
Protocol
Main Firmware
Volume
DXE Dispatcher
Driver C
Dependent:
A
B
C
Scheduled:
Driver B
Initializing:
(CPU_AP)
Initialized:
Driver A
Dependency Expression:
CPU_AP
TRUE
Evaluates To:
FALSE
TRUE
(Timer_AP)
DXE
Foundation
Driver Execution Environment
DXE Foundation Dispatcher
Handle Database
Main Firmware
Volume
DXE Dispatcher
`
1
Loaded Image
Protocol
Driver C
Dependent:
A
Scheduled:
B
B
C
C
Driver B
Initializing:
(CPU_AP)
Initialized:
Driver A
Dependency Expression:
CPU_AP
AND TIMER_AP
TRUE
FALSE
TRUE
Evaluates To: FALSE
(Timer_AP)
DXE
Foundation
Driver Execution Environment
DXE Foundation Dispatcher
Main Firmware
Volume
Handle Database
DXE Dispatcher
`
1
2
Loaded Image
Protocol
CPU
Architectural
Protocol
Driver C
Dependent:
A
Scheduled:
B
B
C
C
Driver B
Initializes
Initializing:
Driver B
(CPU_AP)
B
Driver A
Dependency Expression:
CPU_AP
AND TIMER_AP
TRUE
(Timer_AP)
Initialized:
Evaluates To:
FALSE
TRUE
DXE
Foundation
Driver Execution Environment
DXE Foundation Dispatcher
Handle Database
Main Firmware
Volume
DXE Dispatcher
`
1
2
Loaded Image
Protocol
CPU
Architectural
Protocol
Driver C
Dependent:
A
Scheduled:
B
B
C
C
Driver B
Initializes
Initializing:
Driver B
(CPU_AP)
B
Driver A
Dependency Expression:
CPU_AP
AND TIMER_AP
TRUE
TRUE
Evaluates To: FALSE
(Timer_AP)
Initialized:
DXE
Foundation
Driver Execution Environment
DXE Foundation Dispatcher
Handle Database
Main Firmware
Volume
DXE Dispatcher
`
1
2
Loaded Image
Protocol
CPU
Architectural
Protocol
Driver C
Dependent:
A
C
Scheduled:
B
A
B
C
C
(CPU_AP)
Initializing:
Initialized:
Driver B
B
Dependency Expression:
CPU_AP
TRUE
CPU_AP AND
AND TIMER_AP
TIMER_AP
TRUE
Evaluates To: FALSE
FALSE
Driver A
(Timer_AP)
DXE
Foundation
Driver Execution Environment
DXE Foundation Dispatcher
Handle Database
DXE Dispatcher
Main Firmware
Volume
`
1
2
Loaded Image
Protocol
CPU
Architectural
Protocol
Driver C
Dependent:
3
Driver A
Initializes
Scheduled:
Driver B
(CPU_AP)
Initializing:
Initialized:
Timer
Architectural
Protocol
A
C
B
A
Dependency Expression:
CPU_AP
TRUE
CPU_AP AND
AND TIMER_AP
TIMER_AP
TRUE
Evaluates To: FALSE
FALSE
Driver A
(Timer_AP)
DXE
Foundation
Driver Execution Environment
DXE Foundation Dispatcher
Handle Database
DXE Dispatcher
Main Firmware
Volume
`
1
2
Loaded Image
Protocol
CPU
Architectural
Protocol
Driver C
Dependent:
3
Driver A
Initializes
Scheduled:
Driver B
(CPU_AP)
Initializing:
Initialized:
Timer
Architectural
Protocol
A
C
B
A
Dependency Expression:
CPU_AP AND TIMER_AP
Evaluates To:
TRUE
Driver A
(Timer_AP)
DXE
Foundation
Driver Execution Environment
DXE Foundation Dispatcher
Handle Database
DXE Dispatcher
Main Firmware
Volume
`
1
2
Loaded Image
Protocol
CPU
Architectural
Protocol
Driver C
Dependent:
A
C
Scheduled:
B
3
Driver B
(CPU_AP)
Initializing:
Initialized:
Timer
Architectural
Protocol
Driver C
Initializes
B
A
C
Dependency Expression:
CPU_AP AND TIMER_AP
Evaluates To:
TRUE
Execution Order Determined at
Runtime Based on Dependencies
Driver A
(Timer_AP)
DXE
Foundation
Agenda
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Overview
DXE Core
DXE Dispatcher
DXE Architectural Protocol
DXE Services
DXE Drivers
DXE – Architectural Protocols
What are Architectural Protocols?
 Low level protocols that support DXE APIs
 Provide support for boot services and runtime services
 Typically touch hardware
 Only called by DXE core (directly)
DXE Core
System
System
Memory
Memory
System
I/O
Memory
Resources
System
MMIO
Memory
Resources
System
Firmware
Memory
Devices
System
Firmware
Memory
Volumes
System
DXE
Memory
Drivers
HOB List
PHIT
HOB
HOB
HOB
EFI Boot Services Table
HOB
HOB
DXE Services
...
System
DXE
Memory
Drivers
HOB
EFI System Table
EFI Runtime Services Table
DXE Core / DXE Dispatcher
Security
Architectural
Protocol
CPU
Architectural
Protocol
Metronome
Architectural
Protocol
Timer
Architectural
Protocol
BDS
Architectural
Protocol
Runtime
Architectural
Protocol
Watchdog
Timer
Architectural
Protocol
Hardware
Variable
Architectural
Protocol
Monotonic
Counter
Architectural
Protocol
Reset
Architectural
Protocol
Status Code
Architectural
Protocol
Real Time
Clock
Architectural
Protocol
DXE – Architectural Protocols
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Boot Service APs
CPU – cache, interrupts, reset, timers
Metronome – periodic signals
Timer – event services
Boot Device Selection (BDS)
Watchdog Timer
Security
Runtime Service APs
Runtime – virtual addressing
Real Time Clock
Reset
Variable Services – nonvolatile storage access
Monotonic Counter
Status Code
DXE – Architectural Protocols

Some APs have dependencies on others.
 Timer requires interrupts (CPU) and IO access
 Watchdog timer requires timer and IO access
 Reset requires CPU and IO access

Dependencies can be satisfied by using one or more of the
following methods to control load order
 Dependency grammar to have DXE load in the correct order
 RegisterProtocolNotify() to be notified when required AP gets
loaded
 Apriori list – file in the file system containing list of filename
GUIDs
DXE – Architectural Protocols
BDS
Security
Status Code
Runtime Services
Variable Services
Watchdog Timer
Realtime Clock
Timer
Metronome
CPU
PCI I/O Abstraction
DXE Core
FDVP
Load Order
Reset
DXE – Architectural Protocols
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CPU APs
FlushDataCache()
EnableInterrupt()/DisableInterrupt()/GetInterruptState()
 RaiseTPL() and RestoreTPL()
Init()
 reset control
RegisterInterruptHandler()
 Used by timer initialization
GetTimerValue()
SetMemoryAttributes()
DXE – Architectural Protocols
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Watchdog Timer
RegisterHandler()
SetTimer()
GetTimer()
Boot Device Select (BDS)
Entry()
 to hand off system to OS loader or system utility
Security
FileAuthenticationState()
DXE – Architectural Protocols
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Real Time Clock APs
RT->GetTime()
RT->SetTime()
RT->GetWakeupTime()
RT->SetWakeupTime()
Reset APs
RT->ResetSystem() – for cold or warm system reset
Status Code
RT->ReportStatusCode()
Agenda

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


Overview
DXE Core
DXE Dispatcher
DXE Architectural Protocol
DXE Services
DXE Drivers
DXE Services

Dispatcher Services
 Dispatch()
 Schedule()
 Trust()

Global Coherency Domain Services
 Used to manage CPU visible memory resources
 Used to manage CPU visible I/O resources
DXE GCD Services


GCD Memory Services
 AddMemorySpace()
 AllocateMemorySpace()
 FreeMemorySpace()
 RemoveMemorySpace()
 GetMemorySpaceDescriptor()
 SetMemorySpaceAttributes()
 GetMemorySpaceMap()
GCD I/O Services
 AddIoSpace()
 AllocateIoSpace()
 FreeIoSpace()
 RemoveIoSpace()
 GetIoSpaceDescriptor()
 GetIoSpaceMap()
Agenda

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


Overview
DXE Core
DXE Dispatcher
DXE Architectural Protocol
DXE Services
DXE Drivers
DXE Drivers



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
DXE drivers are DXE Components that
Initialize the platform
Provide the services required to
 boot an UEFI-compliant operating system
 Or
 a set of UEFI-compliant system utilities.
DXE drivers may consume
UEFI Boot Services
UEFI Runtime Services
DXE Services
Classification of DXE Drivers

According to Functionality
 Early DXE Drivers
 DXE Drivers that follow the UEFI Driver Model

According to Life Cycle
 Boot service drivers
 Runtime drivers
Early DXE Drivers

Early DXE Drivers
 Basic services
 Processor initialization code
 Chipset initialization code
 Platform initialization code
 DXE Architectural Protocols
 Not all services are available
 Execution order depends on dependency expressions
 As much initialization should be deferred to DXE drivers
that follow UEFI Driver Model
DXE Drivers that Follow the
UEFI Driver Model

DXE Drivers that follow the UEFI Driver Model
 Do not touch any hardware resources when they
initialize
 Register a Driver Binding Protocol interface
 Ultimately provide software abstraction for console
devices and boot devices
 Do not need to be concerned with dependency
expressions
 Selected by BDS