Slashdot Mirror
Looking Closely at the Restrictions of Linux on the PS2
Hal-kun writes: "I wrote an interesting article about Sony's upcoming Linux distro for the PS2 and some intellectual property concerns I have with it. It's an intresting look at how Sony limits the ability to have full access to the system, yet being able to keep it under GPL."
A couble of comments:
1) Its actually not "bad areas" that Sony is using with PS2 discs. They have encoded a sort of sub-signal onto the disc that bruners cannot recreate and more important, nor can asian "copy shops".
2) The PS1 discs has a error written into the TOC but CloneCD (aand others) deals with this without problems.
3) Developers can actually buy CDR's at Sony with the copyprotection on, so they can burn discs to test on non development equipment.
4) Sonys DVD-ROM's has the same copyprotection buildin as the CD's. So even with a DVD-R (Burned on the A03) you cannot boot with a modchip.
I hadn't realised until now how that was done, they must be using the same sync on green on/off functionality to restrict our playback.
When this was first discovered at launch a lot of people (myself included) were upset about this, if you want to play games at their best AND watch dvd's you have to keep switching leads. Sony claim they HAD to limit playback in this way (cos of the marcovision thing, I think), but most standalone dvd's over here, including ones manufactured by Sony DO let you play dvd's over an RGB lead.
Thankfully DVD Regionx from Datel enables dvd playback through rgb, as well as allowing discs from any region to be played.
<Electronics_lession>
For *any* monitor, it is required to know when a horizontal scan line starts, when it stops, and where the top of the screen is. This information is called sync, and is seperate from the video data that paints the image.
In a normal, modern monitor, five signal lines go to the monitor:
Now, the hsync line is in one state while the monitor is scanning across the display, and another state during the time the electron beam is being swept back across the display (the horizontal retrace interval). The vsync line is in one state when the screen is being painted, and another when the beam is brought back to the top of the screen (the vertical retrace.)
Now, in older monitors, to save signal lines, they used a technique call "sync on green". During the normal horizontal scan, the green line was at a voltage between 0V and 1V, with 1V being full on green, and 0V being no green. During horizontal retrace, the green line went to -0.5V to signal sync. During vertical retrace, the green line was -0.5V during the whole scan line, and went to 0V during the horizontal retrace. By suitable filtering and phase-lock techniques the actual sync signals were recovered from this. Thus, a sync on green monitor required only 3 signal lines.
Now, if you take a normal monitor, and connect it to a sync-on-green system, the monitor's sync inputs will be undriven. A multirate monitor will simply turn off it's drive to the screen, assuming the computer is turned off.
Sync on green has nothing to do with "synchronizing the red and blue signals with the green" - they are synchronous in time already.
Your best bet for such things is to go to a computer graveyard, and try to find an old monitor. Many older monitors would do sync on green as well as normal discrete sync.
</Electronics_lession>
<Rant>
What I don't understand is why everybody is getting so excited about this. Sony is locking you away from the hardware - without a massive RE effort you are not going to be able to do much with this system. For the price of the PS2 and the Linux distro and hardware you could by far more useful devices (until somebody cracks all the hardware protection). Assuming somebody does manage to get raw HW access, Sony will make that person disappear in a puff of red smoke.
Why don't we all just ignore these people until they learn to play nice with others? Look at the Atari 2600, the Apple ][, the PC. They were successful because people could hack them. Sony and Apple learned the wrong lesson ("We must have total control! Nobody BUT US CAN MAKE MONEY OFF THIS") rather than the right lesson ("Hardware like parachute - works best when open.").
</Rant>
www.eFax.com are spammers
I have a japanese ps2-linux kit (although really the only thing that makes it japanese is the machine it's running on) and I am personally very glad I have it.
1. as a developer, this gives us a cheap way to give artists/designers tools that actually show how elements will look on the TV (colors), and how PS2 specific art (graphics/sound/etc) will be rendered. it is a huge savings to be able to use TCP/IP and open-gl for these tools. it also makes working from home a bit simpler, and who can argue with that?
2. as a programmer, I get to program two things that I enjoy (just for the hell of it) - linux and ps2 hardware - at the same time. sure, I have a few PCs here that would kick the linux kits ass easily at generic apps, esp. memory-hungry and cpu-hungry apps. but just for the fun of using linux on an embedded system, it's great.
and for a wannabe console game programmer, shit -it's an awesome place to start. you can begin with the familiar ground (linux/open-gl/etc) and slowly move to the real hardware specific features.
3. as for GPL vs. Sony's IP rights, I think some people around here have this impression that there is some guy at sony "headquarters" in japan making this hugely compicated agenda that is surely not in the best interest of the open software crowd. I'm pretty damn sure this isn't the case, and as a matter of fact, I think there are some people at sony who have gone pretty damn far (maybe even slightly beyond what their lawyers would consider comfortable) to show their support for the open software crowd. some people there do care, but some don't. same as everywhere. and instead of bitching about it, I'm damn happy that they've taking this starting step (opposed to how closed the PS1 was).
there were probably a couple of people at sony who went to bat saying that they should release this linux kit because there'd be a ton of people who'd be very glad to have it. and that stance was probably pretty unpopular. so the message I want to send to those guys it "hey thanks, great job. good start!" so that maybe in the future, they'll go a little bit farther next time and have even fewer things closed.
flame if you want.
whatever.
In no way was this designed to be some sort of feasible Linux system in a general sense. Sony don't particularly want you hacking about making drivers and doing weird things with their hardware. In fact they've made it pretty damn difficult to do so. And as for ideas on hacking it to gain more access... I respecfully suggest that people making these overtures don't have that much of an understanding on what the PS2 hardware is like.
However if someone absorbs much of the included hardware manuals, gets a handle on some of the DMA issues and maybe learns a bit of vector unit assembly then they're some ways down the road in becoming a useful PS2 commercial developer. Is that anyone here? I doubt it.
I'm sure the debate will continue and some hard-core Linux evangelists will crow about license issues and that there ought to be unfettered access to the hardware. That's not Sony's agenda and, to be honest, why is this much of a desirable thing anyway. Quite clearly Linux on a PC is more useful in any event.
I'd really like to know if this will sell anything in the West at all. The demand for games developers is such that you can get an entry level job straight out of university anyway. If you're going to work on PS2 dev, they'll factor in that training on the 'real steel' dev-kits anyhow.
If you wanted to do home-brew game development for console-like applications, the Gameboy Advance is an infinitely more feasible platform from a technical point of view. Coupled with the fact you could give a copy of your work to someone else or demonstrate it on a stock GBA, it's got to be a more attractive platform for this sort of thing.
Yes, but it's worth considering how involved the work-around is. For example, in the realm of books, the copy-protection work-around involves the rather tedious task of either manually retyping the entire book or using a scanner and OCR software. It's doable, but it's certainly not easy.
Likewise, if the PS2 work-around is inconvenient enough (such as the traditional mod-chip solution, which requires playing around with solder and several hundred dollars worth of easily broken Playstation internal hardware), it's going to reduce the number of people that use it. Compare this to the Dreamcast, where the copy protection was (as I understand it) completely defeatable on the software level -- you just had to download games cracked by other people, and you were set. The only requirements were having broadband and a CD burner (or a nearby friend with the same).
Anyway, I suspect one of the reasons behind Sony's goofy intermediate device driver system is to keep the Linux kit from turning into a easy, modchip-free copy protection breaker. Without their (admittedly annoying) protection system in place, I could see the PS2 Linux system being used as a giant bootloader to get the PS2 to read and execute a burned game. There would still be other software hurdles to overcome (such as any in-game copy protection checks and chopping things down to fit on a CD), but those're the same purely software hurdles that're already regularly tackled by cracking groups.
In short, even though I don't like the protection mechanisms Sony's introduced, I can understand why they did it.