Chapter 4 - DSpace at Waseda University

Chapter 2
2.3 Embedded Linux
An embedded OS has to supports developing environment such as middleware, library,
development tools, and analysis tools for analysis kernel problems. The Linux kernel that is
the commonly OS among embedded system OSes. Nevertheless, embedded systems such as
cellular phone and real-time applied product have been used by the RTOS because of its
required time constraint such as hard real-time systems. However, rapidly improved
performance of embedded systems causes limitation of systems based on RTOS. Therefore
Linux OS that strengthened real-time characteristic engages public attention again.
Embedded Linux means simply Linux that used in the embedded system. Early embedded
Linux was developed with small memory and low performance processor. Therefore
embedded Linux has been minimized its size and functions, and customized because of
limitation to be built in small memory. Above conditions are essential factor of embedded
Linux. Nevertheless, the embedded Linux was applied in various products.
There are lots of reasons that Linux get the spotlight in the embedded system industry.
Three big reasons are as follows. First, there is no royalty and licensing cost. Open source
licensing agreement is one of reasons for being Linux today. Second, it supports functions
that RTOS could not support for various devices such as smartphone and PDA etc. Gradually
embedded devices are going to change by various demands of memory size, wireless internet,
and hard disk etc. It means that the demands could not be existed from RTOS are going to be
more bigger and bigger such as safety, various graphic user interface (GUI), memory security,
and support personal information etc. If developing of the embedded system, there is no need
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