Modules

Some embedded Linux failures are easy to misread:

• the same rootfs boots with one kernel but not another
• a driver module exists in rootfs, but the device is unavailable during boot
• no serial log appears, so the system looks dead
• after changing bootloader variables, the system mounts the wrong partition
• the application is unchanged, but device nodes appear in a different order

These problems are not always application or rootfs problems. Device behavior is strongly shaped by three things: