Xenia - An Xbox 360 emulator

by devbug • 13 years ago

159 73 13 years ago

tasoeur• 13 years ago

That's a great project and I'm going to dive into the source pretty soon! However I'm not sure I really like the tone used in the README.md... :/

lowmagnet• 13 years ago

That's rather neat, even though it can't run the games.

I can understand the tone in the README.md because a lot of 'gamers', even the technically oriented ones, expect a lot from the word 'emulator'.

legacy2013• 13 years ago

yea, a lot of people would be submitting issues that they can't run a game without those first disclaimers

dippyskoodlez3• 13 years ago

The amount of traffic this is going to get is probably a bit nuts, so it's pretty well deserved imo.

If your feelings are hurt by someone not wanting to get hammered with idiotic requests/e-mails about a very clear alpha 'project', you should maybe reconsider your ISP payments.

Freestyler_3• 13 years ago

Agreed, A good note to not trust anything claiming to be the finished/working version of this is in its place. But I can't but wonder how those people get there anyway. Linkbait? First many people get lured in then hope some are going to help, be rude to the rest and tell them to get off. mhh I don't know...

Untit1ed• 13 years ago

Makes sense... can you imagine how many 12 year olds are gonna find this as a result of googling "Xbox 360 emulator" and send him poorly spelled emails about how to install it on their parents' iPad?

catilac• 13 years ago

I agree. I can't stand the tone. OSDev.org does a good job of managing peoples expectations without insulting people. Its possible to be clear and concise without resorting to using abusive language.

jyrkesh• 13 years ago

As others have said, the word "emulator" draws a distinct crowd who is otherwise (almost) completely non-technical. Having frequented a lot of developer forums for both, I'd say it's analogous to many of the sorts of threads you get about Android development on XDA.

afhof• 13 years ago

The "I'm doing this and I don't give a damn about you" attitude I think has at least some merit. If the lead programmer is good, its better if he/she can say no. If there is a correlation between being an asshole and being successful I haven't seen it.

tiger10guy• 13 years ago

Well put.

anonymousab2• 13 years ago

Can't exactly download/build this on my current machine. What does it actually do so far?

dippyskoodlez3• 13 years ago

Step 1.) read the readme.

anonymousab2• 13 years ago

No currently supported features, but I assume it actually does...something. Or serves some early purpose towards the development of a 'complete' emulator.

justin_• 13 years ago

The developer made some interesting posts about how the emulator will work on his blog a couple years back:

http://www.noxa.org/blog/

snowman41• 13 years ago

Great link, thanks.

whalesalad2• 13 years ago

One thing I've wondered... And this is somewhat unrelated, is why the Xbox One doesn't run 360 games. One of the core features of it's OS is the fact that everything is running in a modified Hyper-V environment. So why couldn't MS have emulated the 360 on the hypervisor?! Will be cool to see this project progress and hopefully running on an Xbox One dev kit.

onedev• 13 years ago

The 360 ran a PowerPC instruction set while the Original Xbox and Xbox One run x86 architecture. The game would have to be rewritten to run on Xbox One.

I'd assume this makes it difficult.

bhouston3• 13 years ago

You can convert instruction sets on the fly, the technology has been around for a while. One big commercial failure that was partly relying on this was Transmeta and their Code Morphing Software: http://en.wikipedia.org/wiki/Code_Morphing_Software

Here is a more general article on the topic:

http://en.wikipedia.org/wiki/Binary_translation

whalesalad2• 13 years ago

That's the whole point of a VM right? OS X could run PowerPC apps with Rosetta when they went Intel. I just assumed that we could do the same since the Xbox One has a beastly processor compared to the aged 360 one.

kabdib• 13 years ago

Binary recompilation is hard, but it's been done (the 360 did this for the original Xbox, which was x86).

Things that kill you are graphics and sound; particularly texture formats (which you don't have the CPU horsepower to convert) and sound (the 360 has a ton of voices in hardware, and this is difficult to emulate in software).

Personally, I don't think it's impossible. But it'd take the right people a couple of years to make it actually work.

eropple• 13 years ago

As I understand it, the Xbox One has a 360 API translation layer. There may be some nonportable assembly code around--there almost certainly is--but (speculative) most use of assembly I've seen in the real world tends to be developed alongside a "slow" C/C++ path which may not be so slow on the Xbox One.

It wouldn't be as purely simple as a recompilation, but it's a conceivable amount of work. Probably be more work than is worth it for many titles, but I'm surprised at least the Big Games don't have support.

jheriko2• 13 years ago

its not very hard actually - you can map the PPC instruction set to the x86 one with a bit of framework around it. more trivially you can write a C program to perform the same functionality as the original CPU. what this means is that you don't have to re-write the game at all - you run the original compiled code, just not on hardware.

I did this many years ago when I learned about the existence of the x86 instruction set as a stepping stone towards understanding/making interpreters, virtual machines and compilers. I recommend anyone do it as a learning exercise.

This stuff is incredibly simple at its core but there is a common misconception because it is 'low level' that is is some how hard or complicated...

Once i knew it was just simple instructions, registers and a few flags coupled with a memory model it was obvious how to achieve... you write C functions for the various flavours of ADD, SUB, LEA, MOV, FSTP, ADDPS etc. by iterating through the stream of bytes and interpreting them in the same way as the CPU (this is always described in the CPU manual in my experience) you can call the right ones in the right sequence. you use some appropriate blob of memory for your registers, flags and other CPU state and some big array of bytes for your emulated memory...

this is what an emulator is at the simplest level, an interpreter for CPU instructions. (of course making the implementation of instructions might necessitate that you do more - e.g. emulating memory, BIOS or more...)

sjmulder• 13 years ago

Xbox 360 used a PowerPC instruction set. It would seem unlikely that emulation could be efficient enough to have it work reliably good and fast.

bhouston3• 13 years ago

It isn't necessary to purely emulate every instruction, you can cache translated code segments like a JIT compiler does. It has been done before for fast x86 emulation on a VLIW chipset: http://en.wikipedia.org/wiki/Code_Morphing_Software

More details: http://en.wikipedia.org/wiki/Binary_translation#Dynamic_bina...

zanny• 13 years ago

In reality you could emulate it. The problem is the xbone doesn't have a powerful enough x86 processor to emulate the powerpc 360. It was around 2010 that mainstream computers matured enough to easily emulate a ps2, for instance.

daeken• 13 years ago

It was around 2010 that mainstream computers matured enough to easily emulate a ps2, for instance.

The PS2 is an incredibly weird architecture, though. Lots of different processors requiring really strict synchronization in weird ways. It's not that the raw horsepower wasn't there for emulation (it has been there since ~2004), but that it's just strange enough that emulating it is brutally difficult.

InclinedPlane• 13 years ago

It would require emulation. And while it's fairly easy to emulate apps compiled for powerpc to run on x86, it's much harder to do so with games while maintaining performance.

PhasmaFelis3• 13 years ago

You'll see a lot of technical answers, all of which are valid; but the overriding reason is that if you're playing your old 360 games, you're not buying new Xbone games. Microsoft takes a loss on every console sold; if you're not regularly purchasing new games at retail prices, they're not interested in serving you.

onemore360• 13 years ago

I don't think Microsoft and Sony think that way. Look at the extraordinary lengths Microsoft and Sony went to in the previous generation to provide back compat -- Microsoft wrote an amazing Xbox emulator, Sony build a whole expensive mini version of the PS2 into early models of the PS3.

And this generation it seems that Sony is trying to provide PS3 emulation using their cloud gaming system.

Some of the benefits of back compat to platform holders:

1) Encourages customers to upgrade sooner and to choose the compatible platform.

2) Increases the roster of games during the first few years of the new console's life.

3) Extends sales of the previous generation hardware and software. (Software because it can be played on both old and new hardware, and hardware because there's more new software available.)

DCKing• 13 years ago

Unlike most of the replies made to your question, I don't think the big problem for Microsoft was emulating PowerPC on an x86 platform to make emulation happen. The real problem with emulating both the PS3 and Xbox 360 is that they were the first consoles with an incredibly complex GPU. The GameCube and PS2 already have chips that are incredibly hard to emulate, and you need a high end PC to do it. The Xbox 360 GPU is much more complex than what's in the GameCube - it's two generations ahead of it with two incredibly complex generations of GPU functions you have to emulate on other hardware. The Xbox 360 GPU can be seen as the very first chip in the generation of GPGPUs to which today's GPUs still belong. It really was a beast of a machine in 2005.

Different GPUs work very differently internally, and the 360 GPU probably is vastly different internally than what's in the Xbox One, despite both being made by the same vendor. The incredible amount of specific GPU hardware optimization, the incredible EDRAM bandwidth and other things that need to be emulated for emulation to work is incredible. That even ignores the performance characteristics of the Xbox 360 CPU - it outperforms even the highest end Haswells today in very specific scenarios (and Microsoft has no hope to emulate this on the weak Xbone CPU). Props to the OP for starting such a daunting project.

If you look at Dolphin's system requirements, the Xbox One does not quite have the power to even emulate a GameCube, a console like the Xbox 360 with an IBM PowerPC CPU and an ATI/AMD GPU but from 2001 instead of 2005. It could never hope to emulate an Xbox 360. It makes me wonder what kind of regular PC hardware is needed eventually to run something like Halo 4.

jheriko2• 13 years ago

The real problem with emulating both the PS3 and Xbox 360 is that they were the first consoles with an incredibly complex GPU

i kind of agree and disagree...

i agree with the idea that the GPU is a big problem, but i dont think the implementation of features on hardware like EDRAM, memexport, half-float textures etc. are especially problematic vs. the general case of the unified memory architecture...

most of those unique features like the EDRAM and memexport were relevant to hardware specific optimisations at the time - modern GPUs can produce equivalent functionality by ignoring the performance characteristics and relying on their horsepower. EDRAM is a very good example of something that you just don't need an equivalent for - you can emulate all that functionality with regular VRAM just fine.

memexport and similar functionality relying on the unified memory architecture is a little more tricky. the real problem i'd imagine would come from the the resulting 'tricks' used for performance and flexibility when feeding the GPU from the CPU side - e.g. being able to memcpy into a vertex buffer or blob of shader parameters instead of going through the DX like interface, which was a genuine and useful optimisation. although iirc MS put some limits on this by failing your cert if you did anything outside of their approved list of workarounds for DirectX performance issues... something which is theoretically very easy to check for in many cases

i can't really see how to workaround that with creating a quite complicated and expensive layer around the memory emulation. for the other features (including memexport) workarounds are possible - if unperformant. memexport is only 'easy' because it is an optimisation provided to do something you could already do but in a much faster way... (and something which is now 'standard' since SM4)

also, as an aside, i think its worth remembering that whilst the PPC CPUs had lots of advantages for fast execution the memory read/write performance was abysmal compared to contemporaneous Intel PC CPUs and many features like branch prediction (always true iirc) and out-of-order execution were also quite far behind the Intel PC counterparts of the time. Today that gap is even larger - although it is certainly true that other things have become slower, these were never the bottleneck in my experience... it was almost always memory and the poor size and performance of the cache.

xanth• 13 years ago

Time to start the cease and desist countdown.

Natsu• 13 years ago

While there are other ways to screw up, like promoting illegal ROMs, emulation itself is legal thanks to Sony vs. Connectix.

grecy• 13 years ago

I wish Connectix had stuck around and continued making Emuators. Virtual Game Station was awesome.

PhasmaFelis3• 13 years ago

I'm amused by how many video game emulator devs insist that they're not for playing video games. (MAME is another big one.)

martindale• 13 years ago

In at least the current legal framework, this declaration of intent is [supposed] to help avoid lawsuits.

In theory, the emulation of a system, in and of itself, is not illegal. The copying or unlicensed use thereof, is.

noxa6• 13 years ago

And why is that difficult to believe? My previous emulation project (https://code.google.com/p/pspplayer/) was the same kind of exercise: do something no one else had done and learn a lot doing it. As a hobbyist the act of doing something is far more fulfilling than the output.

PhasmaFelis3• 13 years ago

It's not difficult to believe, it's just funny. Devoting an enormous amount of time and energy to understanding and reproducing a device whose only purpose is to play video games while insisting that you're not interested in video games is a pretty funny thing to do.

I mean, I obsess over odd stuff too, I'd guess most of us do, but it's important to keep a sense of humor about it.

mkr-hn• 13 years ago

Non-piracy emulation projects are the only way to explain NES emulators written in Visual Basic and JavaScript.

yareally2• 13 years ago

Never been curious enough about how something works to try to replicate it?

noxa6• 13 years ago

Author here. Yeah, the readme is meant to scare off people. Even with it I still get people on IRC or email asking me if they can play game X or where they can get a copy. The note about no downloads is for all those who download 360 emulators from shady YouTube links and such - there's a surprising number of fakes packed with malware and viruses floating around.

Status of the project is that it's coming along well, after a long period of inactivity. Many games get to title screens though don't draw much. I'm really hoping AMD gets its shit together and releases Mantle soon, as that will make emulating the GPU related things significantly easier.

MartinCron• 13 years ago

Totally off-topic, but I think that's a pretty cool name. I've been looking to marine life for name inspiration myself.

frik• 13 years ago

Maybe upload some screenshots, or videos?

fidz• 13 years ago

A little bit OOT, why do you use .jp for the domain?

noxa6• 13 years ago

All the other TLDs (xenia.com, etc) are squatted/taken. And .jp is cool :)

ck2• 13 years ago

How many C&D have you gotten from Microsoft's well funded lawyers yet?

Hopefully you are not in US but they are pretty embedded in every country at this point.

mauricio824• 13 years ago

I was just looking at the readme and it says R9 cards and up are required for mantle. Mantle only requires a GCN card and HD 77xx-79xx work fine.

andrewf• 13 years ago

I'm really curious about which new (Windows 8-only) APIs are potentially useful.

noxa6• 13 years ago

There are a bunch related to D3D, and I'm currently using RtlAddGrowableFunctionTable in the JIT to get proper stack walking (previously this was really painful). There are also some kernel primitives I'd like to take advantage of once things are working to do some cool memory tricks and hopefully speed things up.

Xenia - An Xbox 360 emulator

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