Difference between development vs. final deployment? How to setup DHCP, TFTP and NFS server? What about a serial terminal console? How to cross compile? Security?
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Development vs. Product Deployment Contents ●
Development Environment
Boot Loader
Embedded Linux Kernel ●
Root File System
Real-World Experience
Product Deployment ● Most embedded systems need to be self-contained ● Operate from internal flash storage to avoid moving parts (HDs) ● Update requires lengthy download - flash - re-boot procedure ● Dynamic data kept on volatile RAM file system Development ● Direct network connection to development workstation ● Linux kernel (and boot loader update) downloaded via TFTP ● Root file system mounted via NFS ● Allows for quick development cycle
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Network Setup Contents ●
Convenient use of protocols for automatic network configuration
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Avoid messing with company network infrastructure
Development Environment
Boot Loader ●
Embedded Linux Kernel ●
Root File System
Real-World Experience
Separate physical network connection ● Embedded target - development workstation Plug-and-play USB network adapter ● No need to open PC to plug in secondary network card ● Drivers readily available in mainstream Linux distributions
DHCP server provides complete development configuration
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Real-World Experience ●
TFTP server transfers images to target ● Embedded Linux kernel ● Boot loader update NFS server serves development root file system to target ● Directory on development host exported as target root ● Cross compiled binaries immediately available for execution 6
Target Console via Serial Terminal Contents
Target console as a simple means for early debugging ● Boot loader and Linux kernel output their progress
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Development Environment
Boot Loader
Embedded Linux Kernel
Root File System
Real-World Experience
UARTs available on most embedded controllers/processors
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Simple and cheap hardware ● Level shifters optionally on special debug adapter ● No need to populate Connectors/headers on production boards
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Serial ports still readily available on Pcs/notebooks ● Use USB to serial adapter on legacy free PCs/notebooks
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Simple terminal application minicom ● -c on and -w parameters to enabe color and line wrap modes
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Cross Compiler Toolchain Contents
Cross compiler allows building executables for target architecture
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Development Environment
Cumbersome to build your own toolchain ● What version of gcc, Glibc or rather uClibc? ● Patches required for my platform?
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Boot Loader
Embedded Linux Kernel ●
Root File System
Real-World Experience
Third party or pre-built toolchains simplify your life ● Careful they are mostly laid out to be installed at a specific location
Target architecture selectable by environment variables
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ARCH= CROSS_COMPILE=
or directly on the command-line via ●
make ARCH= CROSS_COMPILE= /bin/busybox
Real-World Experience
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Configure & Build BusyBox Contents
Download source from busybox.net
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Development Environment
Extract and optionally patch source
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Boot Loader
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tar xjvf busybox1.12.0.tar.bz2; cd busybox1.12.0
