Java-Based x86 Emulator

jaavaaguru writes "Researchers at Oxford University have produced a Java-based x86 emulator that they hope will be useful in testing applications and learning about viruses without damaging the host, utilizing the robust sandboxing that Java provides. They have an online demo available that boots DOS and has some games to play. Being purely Java, this emulator should be able to run on almost anything, including cell phones." The code is not yet available outside the Oxford community; the developers are said to be working on a suitable general license. In the meantime the code can be licensed on a case-by-case basis.

Comments

Interesting, but

[dreamchaser]

I can only imagine that this will make even Bochs look fast in comparison!

Still, I'd love to tinker with this from a 'gee whiz' standpoint.

Re:Interesting, but

[Qwertie]

I'd have to agree. Using instruction-by-instruction emulation, a C++ based SNES emulator I wrote around 1998 used at least 150Mhz of processing power to emulate the SNES' 3Mhz processor. When I rewrote it in assembly, it was 5-10 times faster. I expect that some pretty sophisticated techniques would be required to exceed a snail's pace when using Java for emulation, eg "dynamic recompilation": translating sections of x86 machine language to Java bytecode... but getting this to work 100% correctly would be pretty tricky.

If it's hard to get good emulation speed in C++, it's even harder in Java.

Re:Interesting, but

[shaitand]

'Java is capable of runtime optimisations not possible with statically compiled languages like C++.'

And with them it can perform almost as fast as C in some fringe cases.

Re:Interesting, but

[Anonymous Coward]

Don't you know, around here:

• All Java is slow
• All Perl is unreadable
• All PHP is insecure
• All JavaScript is a useless intrusion into your browser

... and all comments like those are written by "experts" who've never written one line in the language in question.

So...

[mriya3]

... now we should say: "x86 assembler: write once, run everywhere (slow as molasses in January)" ?

Well for one

[brunes69]

For one this will let you run X86 DOS applications on a SPARC for example.

I'd like you to point me to the support page for VMWare on SPARC... oh wait that's cause there isn't one. QEMU can't even run most applications on a SPARC.

And forget about ARM.

I think this is great. Java is not as slow as people seem to think it is. One thing Java 5 (and 6) have that actually benefits virtualization is dynamic recompilation... the JVM knows the instruction sdequences better than the original author, and in theory can optimize the code paths in ways writing a virtualizer in assembly or C++ can not.

Re:Well for one

[daeg]

If you are using Firefox with Java and having ridiculous applet startup times, you need to disable your Java Cache. This is Java's fault, not Firefox's (supposedly).

Under the Java control applet, under the General tab, click "Settings..." under "Temporary Internet Files". Then click "View Applets...". It will take a moment to load (or in my case, 2-3 minutes). Then UNcheck "Enable Caching". Firefox now starts my applets almost instantly. This doesn't affect downloaded Java applications such as Azureus or Eclipse (both of which I use extensively).

Hope this helps.

can you run java in the x86?

[leuk_he]

THe next question would be: can you run java in the x86 emulator that runs an other emulator that runs java, that runs an other emulator.

Just like the old days when you ran windows real mode under a windows 386 mode windows.