Jave on Embedded Linux

Is that 32 MB flash all that you have for persistent storage? A full J2SE version of the JRE on Linux will run you more than that when decompressed, even with all the optional pieces removed. You would need to look for a J2ME virtual machine.

is a non- commercial J2ME implementation for Linux/x86. The page claims tht Sun sells a commercially distributable version as well.

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I am much indebted for your attention and was full of gratitude.

I have more quistions. I have more storage that is file system (ext2) using Compact Flash(512MB, Sandisk). Could I build the J2SE on my embedded system? If you have information about installation of J2SE on an embedded system, please send me.

Thank you, and best regards

Y.K. Moon

hi,

I installed kaffe 1.1.6 on a embedded platform, based on MIPS: it works with AWT, not SWING. I started using the standard diistribution, with some month of works :-)

You can try compiling it for your target, see the errors, and ask in the kaffe mailing list: it gives a good support

bye giammy

-- Gianluca Moro

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If you have any kind of graphical output (browser and/or Java console), you need to include a mininum X installation. 512M would be tight, 1G would be better. However, with any kind of GUI, 64M RAM is not enough. We had a Java servlet apps that starts up with 100M without anything else running.

Of course you can, but you have to spend lots of time striping it down to fit your system.

This is simply not true. Taken literally, we had GUIs even before 1985 when Windows 1.0 came out, and 64MB of RAM was a hell of a lot of RAM back in those days. But even if you restrict yourself to "modern GUIs", there are still plenty of lightweight ones out there. In fact, there are GUIs specifically designed for embedded Linux. See, for example the MatchBox project:

with full unicode support and theme switching, and yet can run on systems with only

40MB of RAM, and the binaries themselves take up a measly 50Kb. That's kilobytes, not megabytes.

If you're running on devices even more constrained than that, there's MicroWindows:

which can run in 64Kb of RAM. Again, note that that's Kilobytes, not Megabytes.

You can find a list of GUIs for embedded Linux at

I didn't see the original post, so I don't know what the OP is planning to do, but if it's something that involves Java 2 SE, the OP may wish to reconsider. I'm not sure Java is the best choice for memory-constrained devices; at least not J2SE.

- Oliver

This page mentioned quarter VGA resolution. The OP asked for touch screen VGA.

Without meanful GUI.

The OP asked for J2SE. Perhaps you should read the post before answering.

Yes, the page *mentions* quarter VGA resolution. It also has screenshots for the Nokia 770 which is of a higher resolution, and the Sony U71 Tablet PC with runs at 800x600, which exceeds VGA. In other words, MatchBox is not "locked" at quarter VGA, which you seemed to be implying by your post.

I assume you mean "meaningful". What's your definition of meaningful? The site there specifically says it provides an API that is compatible with X Windows and Win32. Here's a short paragraph from the page I linked above:

Microwindows is essentially a layered design that allows different layers to be used or rewritten to suite the needs of the implementation. At the lowest level, screen, mouse/touchpad and keyboard drivers provide access to the actual display and other user-input hardware. At the mid level, a portable graphics engine is implemented, providing support for line draws, area fills, polygons, clipping and color models. At the upper level, various API's are implemented providing access to the graphics applications programmer.

According to

the latest release now supports handwriting recognition, graphics keyboard, and a new window manager. What more do you need before the GUI becomes "meaningful"?

As I mentioned, I did not see the original post. For whatever reasons, my newsgroup decided to discard it. As I also mentioned, I don't think J2SE is the right choice for whatever the OP wants to do, given the limited information I've seen in the form of quotes in your post.

Additionally, I think you are not in a good position to accuse me of not reading the original post when it seems to me that you dismissed the solutions I provided without actually reading the URLs I linked to.

- Oliver

128M flash and no Java

No talks of Java at all.

Yes, you are right.

...

We are not asking for window APIs. We are asking for Java, i.e. J2SE API.

I have not dissmissed solutions that meet the requirements. Please provide links to successful implementation of J2SE on 64M memory. I can provide a 128M J2SE system, but not on 64M. Sure, you can run it with 64M and 64M swap file on Flash, but don't forget to replace the flash every couple of months.

The OP's post finally came through, and I see that (s)he wrote that she wants J2SE or J2ME, so actually, yes, you did dismiss solutions that met the requirement. But my main gripe was not whether or not you dismissed solutions that met the requirement, but rather that you dismissed solutions without actually reading about them, and then proceed to chatise me for not reading the original post after I had already said I wasn't able to see the original post.

Anyway, it doesn't matter to me. There's two directions that I can think of for this thread can go from here. One is that we get into an argument of who was right and who was wrong. The other is that we try to post information that the OP may find helpful. I'm going to try to steer the thread back towards the latter. We'll see what happens from there.

I couldn't find an implementation of J2SE, but I found one for PersonalJava. The Sharp Zaurus PDA has 64MB of RAM, and supports PersonalJava via the Jeode JVM. You can see pictures of it at

In case (like me) you don't know much about PersonalJava, from Sun's website,

In terms of target device capacity, PersonalJava sits between J2SE and the CLDC/MIDP stack of J2ME.

So it's not quite J2SE, but it's more than J2ME. PersonalJava might be another route the OP may wish to look at if (s)he finds (s)he cannot fit J2SE on the device in question.

There also happens to be a guide to Java on embedded Linux located at

. The OP may be particularly interested in part 4, entitled "Java products of interest to Embedded Linux based system developers".

- Oliver

Wouldn't you know it -- immediately after my post saying I can't find a successful implementation of J2SE on 64MB DRAM, I find one:

- Oliver

Servers.

You can pick and choose the context if you want. Let me repeat this: the requirements are for a VGA grade GUI (not handicapped 1/4 VGA) with real Java (not subset of Java) on 64M of code space (NOR flash or RAM).

Servers.

You can pick and choose the context if you want. Let me repeat this: the requirements are for a VGA grade GUI (not handicapped 1/4 VGA) with real Java (not subset of Java) on 64M of code space (NOR flash or RAM).

These are all server units (no real GUI), except for the parking locator. There is no indication of J2SE running on the parking locator either.

Maybe the Slug guys can help you, I think they use the same processor and are open for other hardware I think:

They have a page how to install Java on it. They are using Jamvm which is very small at the expense of some performance.

Hope this helps, kind regards,

Peter Kriens

Hi,

a graphical installation (X server - TinyX, also called Kdrive) needs 6M flash and 3RAM. kaffe 1.1.6 need 12M flash, 6M RAM with this anvironment you can run graphical applications written in java with AWT (in a machine with 32Mflash, 32MRAM)

bye giammy

-- Gianluca Moro

ISCRIVITI alla Mailing List Italiana su LINUX EMBEDDED snipped-for-privacy@yahoo.com Visit