Presented by: GREG UNGERER Lineo Inc 825 Stanley St Woolloongabba Qld 4102 Australia Ph: Building x86 Based Embedded Linux Systems (C) Copyright 2001, Lineo Inc (

1. What is an Embedded System? 2. Why x86 CPU's and Linux 3. Howto (booting, kernel, libraries, apps, etc) 4. Demos 5. Thoughts 6. References PRESENTATION OUTLINE (C) Copyright 2001, Lineo (

"Computing system used within some device or product whose primary function is not to be a computer ” • minimal hardware • reduced/simple or no user interface • physical and cost constraints  " hidden"” from user What is an Embedded System? (C) Copyright 2001, Lineo (

• not technical reasons! • well understood, documented and common • multiple silicon vendors • wide range of performance and price points • flow down from PC/workstations Why x86 CPU? (C) Copyright 2001, Lineo (

• source code available • low cost, no license fees • tools freely available (and modifiable) • advanced functionality and features • huge range of software available • active development community • standardized and well known API sets Why use Open Source? (C) Copyright 2001, Lineo (

• no video console • no mass storage (no hard drive) • minimal RAM • FLASH or ROM as non-volatile storage • how to boot? • how to debug (kernel, apps, etc)? Problems? (C) Copyright 2001, Lineo (

• x86 boot is complicated (backwards compatibility) • license a conventional BIOS ($$$) • develop your own BIOS (boot loader) • flexible (can use with other OS) • fast • support FLASH and miscellaneous hardware • augment Linux kernel with a loader System Boot (C) Copyright 2001, Lineo (

• very minimal changes required • configure to suit hardware • remove unwanted drivers • may need to develop new drivers for new hardware Linux Kernel (C) Copyright 2001, Lineo (

• FLASH or ROM for file store • MTD (Memory Technology Driver) • ROMfs filesystem for read only • JFFS/JFFS2 for real read/write filesystem in FLASH • cramfs in newest Linux kernels • RAM disks can be useful FLASH and Filesystems (C) Copyright 2001, Lineo (

• Glibc is common choice • very large ~1.5MB • can be leaned up with special tools • uC-libc • light weight ~0.2MB • not a full implementation of standard libc • shared libraries a good thing Libraries (C) Copyright 2001, Lineo (

• standard Linux apps mostly • some specialized applications around • busybox - standard file and system utilities • sash - small shell • roll your own or use packaged binaries Applications (C) Copyright 2001, Lineo (

• be very carefull of host build environment  don ’ t use local header files  don ' t link against local libraries • standard gcc/gas/ld tool chain • as86/bcc for boot loader (real mode x86) Tools (C) Copyright 2001, Lineo (

• VPN router • NAS box Demos (C) Copyright 2001, Lineo (

• you can do embedded with x86  don ' t expect a PC/Workstation when you do • think small Thoughts (C) Copyright 2001, Lineo (

• Linux Documentation • Embedded applications (busybox, sash and more) • MTD driver pages REFERENCES (C) Copyright 2001, Lineo (