Inside The Windows PreBoot Environment.ppt

Inside The Windows Pre-Boot Environment Andrew RitzDevelopment ManagerCore Platform Architecture TeamMicrosoft Corporation Agenda What is firmware (and how does Windows use it)? Multi-OS Firmware roadmap for Windows Windows Boot Environment overview Deployment Guidelines for Boot Environment What Is FirmwarePower on sequence Installed with a computer in non-volatile location (PROM\EEPROM) Initializes low level hardware Initializes memory controller timings, powers on critical boot devices Hands off control to operating system loader Operating system loader uses firmware interfaces to initializethe operating system Refer to as pre-boot firmware Examples: BIOS and EFI What Is FirmwareLimited runtime usage Firmware may still be involved after operating system starts This is called runtime firmware Operating system normally strives to place runtime firmware into a sandbox for reliability An exception is System Management Mode (SMM) firmware Firmware is used in cases where a high-performance WDM driver does not exist Handles some of the specifics of a particular platform running Windows What Is firmwareLimited runtime usage Advanced Configuration and Power Interface (ACPI) defines an industry standard for runtime firmware Primary supported runtime firmware interface for Windows Microsoft co-authored industry standard ACPI specification Used to identify and configure ‘soldered on motherboard’ hardware and more Asynchronously notifies operating system of changes inhardware (e.g., when a laptop switches from AC tobattery power) Firmware runs in an OS-provided virtual machine BIOS Firmware (aka PC/AT)De-facto boot firmware standard Mechanism used to boot PCs for the last 25+ years All x86/x64 Windows machines on the market support BIOS firmware BIOS is a real mode environment 16-bit real-mode interfaces BIOS showing its age Over twenty five years old Documentation is scattered Interfaces have evolved in an ad hoc manner as technical advances exposed limita