Tel ： 同济大学软件学院 UEFI 与固件程序设计

What’s the UEFI? 继续 返回 UEFI (Unified Extensible Firmware Interface) 是由英特尔公 司联合业界共同提出的一种欲在未来电脑系统中替代传统 BIOS (Legacy BIOS) 的升级解决方案。 Another question, What’s the BIOS?

What’s the BIOS? 继续 返回 BIOS (Basic Input and Output System) 基本输入输出系统，它是 一组固化到计算机内主板上一个 ROM 芯片上的程序，它保存 着计算机最重要的开机上电自检、硬件初始化程序和系统底 层的服务程序等。 硬件逻辑 Push Power Button CPU Reset RTC BIOS OS Found MBR

继续 返回 Agenda –BIOS background History History Functions Functions Legacy BIOS’s Flaws Legacy BIOS’s Flaws Change Change

继续 返回 BIOS background -- History Before firmware— Switchs on a piece of plywood Before firmware— Switchs on a piece of plywood BIOS-- for original IBM PC/XT and PC/AT in 1980s BIOS-- for original IBM PC/XT and PC/AT in 1980s EFI -- Spring 2000 IDF (Intel Developer’s Forum) EFI -- Spring 2000 IDF (Intel Developer’s Forum) -- EFI 1.10 specification UEFI – Originated from the EFI 1.10 specification UEFI – Originated from the EFI 1.10 specification --Updated and managed by the Unified EFI Forum --Updated and managed by the Unified EFI Forum

继续 返回 BIOS background -- Functions Based on 8086 architecture Based on 8086 architecture POST—Power On Self Test POST—Power On Self Test A group of clearly defined OS-independent interface for A group of clearly defined OS-independent interface for hardware hardware  Int10 for Video service  Int13 disk service  Int16 keyboard service  Int18 BIOS ROM loader  Int19 bootstrap loader Availability of MS-DOS outside of IBM allowed applications Availability of MS-DOS outside of IBM allowed applications to run equally well across different brands of box "PC clones". to run equally well across different brands of box "PC clones".

继续 返回 BIOS background -- Legacy BIOS’s Flaws It is not platform independent, it highly depends on Intel 8086 Software Interrupt model It is not platform independent, it highly depends on Intel 8086 Software Interrupt model  Real mode  16-bits register access  No memory address beyond 1MB  Option ROM space limited to below 1MB Modern Intel CPU architecture has come to 32bits, 64bits protection mode, with HT and Multi-core, but for compatibility, it should still boot up in 16 bit real mode Modern Intel CPU architecture has come to 32bits, 64bits protection mode, with HT and Multi-core, but for compatibility, it should still boot up in 16 bit real mode

继续 返回 BIOS background – Flaws (cont.) It is inaccessible to boot 64bits system which still call into 16 bit legacy firmware when Itanium processor family come into life. It is inaccessible to boot 64bits system which still call into 16 bit legacy firmware when Itanium processor family come into life. More and more new technology come out, like VT, LT etc. It is very hard to enable those technology in the whole eco-system quickly in legacy BIOS More and more new technology come out, like VT, LT etc. It is very hard to enable those technology in the whole eco-system quickly in legacy BIOS Architecture independent is the key for the next generation BIOS, that is where the EFI come from, single driver can work in x86, Itanium and XScale etc. Architecture independent is the key for the next generation BIOS, that is where the EFI come from, single driver can work in x86, Itanium and XScale etc.

继续 返回 BIOS background – Flaws (cont.) Code Real Mode Assembler Spaghetti Scalability Complexity Maintenance Issue Spec None!Compatibility OS Loader Tied to HW and BIOS Slows innovation Carries legacy

继续 返回 BIOS background – Change Unified Extensible Firmware Interface Unified Extensible Firmware Interface UEFI is an interface specification UEFI is an interface specification download from Abstracts the platform from OS Abstracts the platform from OS Includes a modular driver model and Includes a modular driver model and CPU-independent option ROMs CPU-independent option ROMs Compatible by design Compatible by design Modular and extensible Modular and extensible Complements existing interfaces Complements existing interfaces Flexible to meet existing and future needs OS Loader Hardware Firmware UEFI Compatibility

继续 返回 BIOS background – Change Code Real Mode Assembler Spaghetti Scaleability Complexity Maintenance Issue Spec None!Compatibility OS Loader Tied to HW and BIOS Slows innovation Carries legacy High level language protected mode code Scaleable and easy to maintain Straight-forward implementation Clearly defined Innovation Legacy migration Abstraction