nice if you can put up with how crappy amd is XD

@Noodle
troll? XD nope just someone who used to be stuck with AMD computers
now how about you comment with something related to the post?

Ok, before we get into a flame war… It all boils down to personal preference.

Anyway. Interesting article, not sure how a casual computer programmer/tinkerer would use the debug mode. If I had to guess I would say AMD probably included it for checking of the chips at ship time.

What on the Earth is the debug mode anyway? These processors already have extensive debug capabilities.

The pass check doesn’t get pushed onto RAM and executed, so I’m sure AMD is trying to figure out which one of their employees leaked the information..

@xorpunk Since this is on the CPU die doing an exhaustive test of all possible passwords would be trivial and incredibly fast. The only information which needed to “leak” was the existence of a password and what register it needed to be in and some approximate information about its effects.

… granted all three of those condition would require some people in the know to have leaked *some* info, you have to remember they probably have to give this information to people like Microsoft for kernel debugging in addition to any contractor willing to sign a super-strict NDA. Eventually someone was bound to let the little bit needed out.

But for example, this hack was someone just waiting for what the *name* of the registers he already knew about were. There are a ton of debugging features on this chip which are known, but it’s completely unknown what the names and exact functions of these are. That’ll be up to the CPU hackers!

Can’t wait to see this implemented in GDB or something similar

The site’s working now(FINALLY) but just in case here’s a cache of the site…

http://www.woodmann.com.nyud.net/collaborative/knowledge/index.php/Super-secret_debug_capabilities_of_AMD_processors_!

This news is overdue…
http://www.mail-archive.com/coreboot@coreboot.org/msg23187.html

What’s this useful for, and why would AMD password-protect it? Would it allow you to re-enable high-end features that were disabled to down-spec a processor, or something? Does AMD even do that? What do they have to gain by hiding debugging features that would presumably allow developers to write better-optimized code for their architectures?

@jeditalian

Yep, but that 6 Core AMD CPU performs like a low end Intel Quad core… So you really aren’t gaining anything at all…

Simply put:

If you want the absolute best performance, go Intel, if you just want to brag about having 6 cores in your PC while barely using 4 of those cores, go AMD.

You get what you pay for… The same goes with ATI and their video cards.

I love CPU easter eggs. If you have K8, query this:

mov eax,8FFFFFFFh
cpuid

If you’re lucky, registers eax, ebx, ecx and edx should return “IT’S HAMMER TIME”. Some of the earlier families (K6 I believe) might return other strings.

You all put your computers on standby. What happens if the fan fails? The video made me think and I now turn the computer off when I’m going out because I don’t want a fire.

So much trolling :) Those pics were RIGHT after Intel incorporated thermal throttling in their cpus, while AMD took a while longer. The thing is that the first Intel Pentium 4 cpu’s were so bad that they would throttle after 5 minutes into a game quartering the frame-rate WITH NO WAY TO TURN OF THERMAL THROTTLING!
But ah well, trolls will be trolls, investment fallacy and all that…

@m1ndtr1p
so are you saying that if i want a quad-core AMD i should buy a 6 core? i have no use for the extra cores anyway, i would be fine with a dual-core, have a single core from 2005-6 and if i were really going to spend around 200 on a cpu i would get the http://www.newegg.com/Product/Product.aspx?Item=N82E16819103727 because if the extra cores aren’t going to be taken advantage of, why would go for 6 at 3.2 when i can have 4 at 3.4, which is 1ghz faster than the 1 core i’m currently working with.
anyway, i choose whatever’s cheapest, because i don’t make over $1k/week like some people. if non-celeron intel chips were more affordable than an equally/lesser rated non-sempron AMD cpu then i would go intel.
i do prefer the feel of any computer with intel inside, with the exception of celeron, but as far as recent cpu’s my experience has only been sempron, turion, celeron, dual-core pentiums, and i3 370m. sempron/celeron=h8 and the one turion i dealt with= fail. dual-core pentium desktop built the same time as mine=better. the pentium and i3 370m laptops were awesome, sempron laptop blew donkeyballs and celeron just blows no matter what.
and i still haven’t figured out this debug shit. is this something i do inside or outside of windows/linux? in or out of a motherboard? just skimming over that page i have no idea what’s going on. “If you own a 64-bit AMD processor, please DO check and report any differences.” that’s what i want to do, but there don’t seem to be any instructions for dummies.

@jeditalian

Use whatever you need, I was merely speaking in terms of pure performance… If a dual core is all you need then that’s what you should get. But as it stands, not many applications are able to fully use 6 cores, hell most have a hard time fully using 4, gaming is the same thing, while some game do take advantage of 4 cores, the majority of the time they’re only 25%-50% stressed so you’re really only using 2 cores max even though it shows all 4 cores being used…

As far as pure speed (IE: Ghz) is concerned, you can’t compare Intel’s clocks speed to AMD’s as they’re both different architectures, it would take a 3.4 Ghz AMD CPU to compete with a 2.6 – 2.8 Ghz Intel CPU using the same amount of cores (on average, depending on the processor obviously)… But like I said, if a dual core is more then enough for whatever you use your PC for, a quad core or 6 core CPU would be way overkill.

That makes sense. Options that are nonstandard are unsupported. If it’s password protected, then they don’t have to worry about people asking questions and trying to support it when its original purpose is in house only that the engineers used.

lol it works for me the link i mean

The question I’d like answered: What is the use to be able to debug the chip?

Please forgive me, I’m the kind of hacker who makes simple products work like much more expensive ones, not deep hardware as this is.

STFU with the Intel vs AMD stuff, fucking n00bs.

On-topic: I don’t see how this might be useful to us. I mean, why would I want to debug the silicon/microcode? But it might be really useful for people trying to find vulnerabilities in these CPUs or people reverse-engineering them – say Intel.

This seems like a clear-cut way to defeat personal encryption on a hardware level (as others have suggested). I wonder if there’s any way to tell if it’s being used already?

Mike

@Will
In the post the dude talks about how the 4th debug option is “dangerous” so I guess it can miss your chip up or brick it in the firmware or something. These commands were left in at the last minute for testing the final version. Programmers do this too in many types of software. It is to debug the chip only. These debug commands would not be great to test software. They are nothing more then just hacks to make sure the product works. It was “passworded” not because it gives info about AMD’s intellectual property, but that you don’t use it because that is not really the function of the chip and you could mess it up. It was just a last minute test.

@Moxion69 If I remember correctly Cyrix was bought (?) by via which continues to produce x86 CPUs.

Could this possibly be used to change the microcode of the CPU?

HAD can you guys do a follow up on this once more information becomes available.

Anyone know of features like this for Intel CPUs?

Would all the Intel > AMD trolls put their e-penises away please? I’m having a hard enough time preventing myself from laughing at your comments.

One thing to note is these registers possibly may be intended to be used to patch the silicon or possibly useful for doing something similar.

@t&p thats why I said unless it aids in the development it is useless to us. and i missed the 4th option is dangerous, but it probably will just reset the chip to full factory condition(i wonder what that would do anyways) or, as you said, brick it.

@Moxion69 i see no academic use even. so the hip has some debug feature. we have absolutley no use or that. well, unless it could aid in hardware problems of the motherboard it is installed on(which is unlikely lol im just coming up with stuff on the go that this could be used for)