RTLinux does not support direct access to any kind of permanent massive storage system, and in particular IDE hard disks. When a RTLinux thread has to store data on the hard disk, it has to use the Linux services. The usual way of doing the transfer is by means of RTFifos: a rtl-task sends the data to Linux through an RTfifo, and then, a Linux process writes this data on the hard disk.

This indirect method is slow, unpredictable and inneficient, since it is executed by Linux (background). Moreover, in some applications, like continuous media applications, it is required a certain degree of predictability. Therefore, for multimedia applications is more convenient that rtl-tasks have access to the hard drive, allowing higher determinism. To achieve this goal is necessary: 1) To port the IDE driver to RTLinux, 2) implement a real-time filesystem, and 3) implement a real-time disk scheduler.

The goal is to provide with a full “block layer” to RTLinux making the design scalable to allow future storage devices drivers implementations and offering a known interface to work with.

Read full paper (PDF download)

 
This article was originally published on LinuxDevices.com and has been donated to the open source community by QuinStreet Inc. Please visit LinuxToday.com for up-to-date news and articles about Linux and open source.