Shared Source Device Emulator from Microsoft

An anonymous reader writes "Microsoft has posted a shared source version of its device emulator (which ships with Visual Studio 2005) for download. Primarily meant for academia to experiment with and build upon, it is licensed under the Microsoft Shared Source Academic License. Since it emulates the ARM processor, it can run all modern Windows Mobile and Windows CE operating systems. Barry Bond, the architect behind the emulator (and also Rotor, one of Microsoft's previous shared source offerings) has a blog post on the release."

Microsoft paradigm shift?

[TheAtomicElec]

With this announcement and the recent release of VirtualPC for free download...
Are we seeing some kind of paradigm shift from Microsoft here? Or is it merely an attempt to increase recently waning market share?

Either way, this seems like it can only be good for consumers.

/me eagerly awaits free download of Windows Vista... ;-)

Re:Microsoft paradigm shift?

[CDarklock]

I think Microsoft is always in the middle of paradigm shift. There's been a lot of study and evaluation of what Microsoft can gain from the open source community, and I think we're now starting to see the fruits of that. The major Shared Source licenses available from Microsoft look an awful lot like GPL, BSD/MIT, and the old "look but don't touch" flavor of Shared Source.

Basically, yes, Microsoft could learn a lot of lessons from open source. It's learning them. But how exactly has the open source community learned from Microsoft?

There is one and only one mechanism Microsoft uses to stay in power: find out what the biggest competitor is doing, and do it better. The open source community may scoff and claim Microsoft can't do this, but the fact is THEY CAN. There's very little you can't do when you can afford to throw hundreds of millions of dollars at a problem, but when you have minimal funding and only fair-weather support from most of your adherents, there's an awful lot you can't do. The open source community needs to be very worried and start looking very hard for ways to respond to this.

ObDoomsdayTheory: Consider the competitive implications of this. We have an ARMV4I emulator for Windows which is released as shared source under the academic license, a close parallel to the GPL which forbids any derivatives that do not run on Microsoft operating systems. Is it feasible that the open source community can EVER develop an ARMV4I emulator for Linux without facing the impending shadow of a lawsuit demanding they *prove* nobody on the project made use of Microsoft's shared source release? Could that ever be proven?

The flaw in the open source model here is that most contributors are anonymous, do not get held accountable for their contributions, and never face any scrutiny as to whether their code is free of trademark and patent claims. If this case went to court, could all the developers on the project be located to appear in court? How could any of them demonstrate that their code was clear of any "contaminant" effect from the Microsoft Shared Source release?

And exactly how much interesting and useful technology *is* Microsoft going to dump onto the market under the Academic Shared Source (ASS... hehehehe oh wait I'm not twelve) license? Will that create a problem for open source developers who want to provide similar functionality? How high *is* the wall Microsoft has created around ARMV4I emulation? Can open source even *contemplate* surmounting it?

Microsoft has a history of learning its competitors' tactics very, very well and using them to slaughter those competitors in the marketplace. There was a time that the saying was nobody ever got fired for buying *IBM*, and everyone was worried about how IBM was going to take over the world and nobody could stop them. But Microsoft stopped the unstoppable, so calling open source invincible and unstoppable doesn't exactly give me warm fuzzies when you look at how IBM is doing these days.

Re:Microsoft paradigm shift?

[dhasenan]

But you can actually use this to develop an OSS emulator for ARM processors. You can use it like an ARM processor for compatibility testing.

As for the source, you can easily compare two codebases to catch potential infringement. Given that the source for each is open, there should be no worries at all; the developers could start by setting up the comparison tool. The real worry would be any patents that Microsoft acquired during the course of creating the emulator.

Cleanroom reverse engineering is a way of b

Re:Microsoft paradigm shift?

[CDarklock]

I'll bet Microsoft can identify and produce each and every developer that worked on this emulator, and that each and every one would testify that they did not refer in any way, shape, or form to any GPL code.

Now try and do that for an open source project. Who wrote this change here? How do you know? Where is he? What's his real name? Will he come out and testify?

It's a much harder question. The courts are also far more likely to believe a professional software developer, where they might not be so quick to

Re:Microsoft paradigm shift?

[bit01]

Will he come out and testify?

Identifying developers is not the same as identifying infringement, whatever they testify. Nobody is going to admit to copying in court, that is self-incriminate, unless they're forced to.

Comparing source for simularity, and using some commonsense about what constitutes simularity, is really the only way to verify whether something is copied.

Just look at the current SCO circus [groklaw.net] to see how complicated this "he said/she said" argument can get.

---

Commercial software big

Nope, usual tricks

[Anonymous Coward]

"(B)Platform Limitation- The licenses granted in sections 2(A) & 2(B) extend only to the software or derivative works that you create that run on a Microsoft Windows operating system product.Further, you may only use the software to emulate running Windows operating system products."

"(E) If you distribute the software or derivative works in source code form you may do so only under this license (i.e., you must include a complete copy of this license with your distribution), and if you distribute the sof

Article also includes information on Optimisation

[Anonymous Coward]

On the blog, he also talks about the steps he took from the v1 code to the v2 code, and some of the optimisations he used.

The information he provided is fairly indepth and can really be applied to many a cpu emulator.

Quite an informative read.

Re:Article also includes information on Optimisati

[tonigonenstein]

In the first part (I didn't bother to read the rest) he explains how they improved the lookup time in the TLB by moving from a linear search... to a hash table. This is algorithm and datastructures 101. The fact that they are proud of this is frightening. If you want to learn optimization techniques, please, do yourself a favor and read something else.

Re:Article also includes information on Optimisati

[Anonymous Coward]

The point is not the use of hashtable but which code paths were sufficiently hot, so that a small change to them caused a high payoff. The main problem in performance optimizations of a non-trivial program is finding which code paths have potential to offer high payoffs, the actual implementation is frequently trivial algorithmic or implementation changes.

So what can mortals run on this?

[drinkypoo]

What all can you or I run on this? Will linux for some ordinarily CE device work?

For those who don't know...

[SanityInAnarchy]

Rotor is the shared-source implementation of .NET. You could think of it as an alternative to Mono -- it's even been ported to Linux. But there must be some reason for Mono still existing -- I'm guessing the shared-source has a bitch of a license.

Re:For those who don't know...

[SirTalon42]

"I'm guessing the shared-source has a bitch of a license"

The 'shared source' license isn't an open source license.

Re:For those who don't know...

[CDarklock]

The "bitch" in the Rotor license is the non-commercial provision. Other than that, it's pretty similar to early BSD license terms.

Re:For those who don't know...

[eosp]

No System.Windows.Forms either.

A no go for hobbyists

[BSAtHome]

According to the license, only people who are in the category: "while attending or employed by an accredited educational institution". So only students, their teachers and researchers (and accredited means not your average school). That means almost nobody, sigh,...

Re:A no go for hobbyists

[InsaneGeek]

Accredited should mean your average school or else you are going to some place that is teaching out of the back of a van. In the US alone there are over 28,800 accredited schools (at least http://www.accreditedschools.org/ [accreditedschools.org] says there are), so your nobody in actuality if we were to use an EXTREMELY low number of only averaging 100 people per school means there are almost 3 million people who would have access to it in the US alone.

Re:A no go for hobbyists

[poot_rootbeer]

Last time I looked we had over 6 billion people in this very world (that is 3 orders of magnitude difference). So still virtually nobody.

Last time I looked, 99 percent of the world's population lacked the resources, intelligence, or inclination to write computer code. That's -2 orders of magnitude from six billion.

So a full 10% of people who MIGHT be interested in this shared source product currently meet the terms of the license, and most others can qualify simply by enrolling at a community college or su

**yawn** ... nothing to see here

[olivermoffat]

If you write applications for Windows Mobile OS's then this interesting. Otherwise... **yawn**... There's a restrictive license and is bundled with Windows Mobile OS Images only, so there's not much use for it other than as a plugin to Visual Studio. There are plenty of fully free-as-in-speech ARM to x86 JITs and ARM emulators out there with more features and less restrictive licenses. In fact, I would bet ARM is the most emulated device out there. Do a search for "ARM Emulator" see for yourself.

Re:**yawn** ... nothing to see here

[Aranth Brainfire]

Welcome to the Internet.

An emulator is more than a CPU core

[tepples]

There are plenty of fully free-as-in-speech ARM to x86 JITs and ARM emulators out there with more features and less restrictive licenses.

But do they also emulate the I/O of a Windows Mobile device, to the point where a PDA owner could backup his handheld and restore it to the emulator?

How short sighted ...

[Anonymous Coward]

I can think of at least one alternative use; the ability to test your web site underneath Pocket IE and Opera for Windows Mobile without having to pay for such a device.