Is it possible to code a device driver in Java?

Question

Introduction

I heard something about writing device drivers in Java (heard as in \"with my ears\", not from the internet) and was wondering... I always thought dev

Answer 1

Device drivers have to be written in a language which can execute in the kernel, either compiled into it, or loaded as a module at runtime. This usually precludes writing device drivers in Java, but I suppose you theoretically could implement a JVM inside a device driver and let it execute Java code. Not that any sane person would want to do that.

On Linux there are several user-land (i.e. non-kernel) implementations of filesystems which uses a common abstraction layer called (fuse) which allows user-land programs to implement things which are typically done in the kernel.

Answer 2

It is possible to compile java code to hardware native (i.e. not JVM bytecode) instructions. See for instance GCJ. With this in hand, you're a lot closer to being able to compile device drivers than you were before.

I don't know how practical it is, though.

Answer 3

The Windows Driver Foundation (WDF) is a Microsoft API that does allow both User and Kernel mode device drivers to be written. This is being done today, and it is now compatible with w2k and later (used to not have w2k as a supported target). There is no reason that JNI calls can't be made to do some work in the JRE . . . ( assuming that JNI is still the way to call Java from C/C++ . . . my knowledge is dated in that arena). This could be an interesting way to have high level algorithms directly munch on data from a USB pipe for something to that effect . . . cool stuff!

Answer 4

Writing Solaris Device Drivers in Java covers a A RAM disk device written in Java.

Another one for Linux. Goes more in depth on why you might want a DD in Java as well (since some people were wondering by the looks of the other posts and comments)

Answer 5

A device driver could be a lot of things

I actually write device drivers in java for a living: drivers for industrial devices, such as scales or weighing devices, packaging machines, barcode scanners, weighing bridges, bag and box printers, ... Java is a really good choice here.

Industrial devices are very different from your home/office devices (e.g. scanners, printers). Especially in manufacturing (e.g. food), companies opt more and more for a centralized server which runs an MES application (e.g. developed in Java) The MES server needs to interface with the devices of the production line, but also contains business logic. Java is a language that can do both.

Where your home/office devices are often built-in to your computer or connected with an USB cable, these industrial devices usually use Ethernet or RS232 connectors. So, in essence, pretty much every language could do the job.

There is not much standardisation in this area yet. Most vendors prefer to create their own protocol for their devices. After all they are hardware builders, not software geniuses. The result is that there is a high diversity of protocols. Some vendors prefer simple plain-text protocols, but others prefer complex binary protocols with CRC codes, framing, ... Sometimes they like to stack multiple protocols (e.g. a vendor specific handshaking algorithm on top of an OPC layer). A strong OOP language has a lot of advantages here.

E.g. I've seen java print at a continuous speed of 100ms/cycle. This includes generating a unique label, sending it to the printer, receiving a confirmation, printing it on paper and applying it to the product using air pressure.

In summary, the power of java:

• It is useful for both business logic as complex interfacing.
• It is just as reliable in communication with sockets as C.
• Some drivers can benifit from Java's OOP power.
• Java is fast enough.

Answer 6

Possible?

Yes but only in special circumstances. Because you can write an operating system in Java and C#, and then, should be able to write device drivers for it. The memory hit to these drivers and operating systems would be substantial.

Probable?

Not likely. Atleast not in the world of Windows or MacOS or even Linux... At least not anytime soon. Because languages like C# and Java depend on the CLR and JVM. The way these languages work means that they cannot effectively be loaded into ring0.

Also, the performance hit would be rather large if managed languages were employed in device drivers.