Procesoare Intel Core 2 Duo "peticite"

2 posts / 0 new

27. June 2007 - 11:07

beranger

Slashdot: Flaws In Intel Processors Quietly Patched:

Quote:

«According to this article in The Inquirer and this Microsoft Knowledge Base article, a fix for some significant problems in many of Intel's most recent processors has been quietly released — by whom is not clear. Patches are available on Microsoft's site. Affected processors include Core 2 Duo E4000/E6000, Core 2 Quad Q6600, Core 2 Xtreme X6800, XC6700, and XC6800. Details on just what has been fixed are scanty (it's called a 'reliability update'), however, it's probably more important than either Intel or Microsoft is openly admitting.»

"Microcode reliability update" nu suna prea explicit, dar dupa cum spunea un comentariu,

Quote:

"Intel processors don’t directly execute instructions anymore. They translate x86 into a series of other operations — an internal code, if you will. Sometimes there are bugs in the code that’s generated. Microcode patches address those bugs."

Asta suna foarte prost: ce ar trebui sa faca utilizatorii de Linux, BSD, HP-UX, AIX, etc.?

Asta e nenorocirea cand un dispozitiv nu face ceea ce ar trebui sa faca, din care cauza dam intr-o postmoderna versiune de Ucenicul Vrajitor, cand lucrurile ne scapa de sub control:

un CPU ar trebui sa execute instructiuni, nu sa "emuleze" prin translatarea in alt microcod;[/*:m]
un buton de pornit/oprit sa opreasca un aparat, nu sa comunice unui circuit logic "peste 5 secunde vreau sa opresti sistemul";[/*:m]
etc.[/*:m]

Un alt comentariu aduce mai multe detalii:

Quote:

«Two months ago, Intel introduced microcode updates for all systems with an Intel® Core(TM) 2 Duo processor. According to an HP Tech Support Document:
While the implications of the issue are difficult to quantify, any of the following symptoms can occur:
* The system may stop responding to keyboard or mouse input.
* A system operating in a Microsoft Windows environment may generate a blue screen.
* A system operating in a Linux environment may generate a kernel panic.

The HP link also indicates the nature of the problem, which should not be OS specific: «This Intel microcode update addresses an improper Translation Lookaside Buffer (TLB) invalidation that may result in unpredictable system behavior such as system hangs or incorrect data.»

Intrebarea ramane: ce ar avea de facut cei care si-au cumparat sau intentioneaza sa isi cumpere un PC sau laptop cu "ultimul racnet" de Intel Core 2 Duo? Din cele doua seturi de patch-uri, care poate fi aplicat si pe altceva decat Windows, si cum?

Chiar nu pare nimanui absurd ca trebuie sa peticesti un procesor... din sistemul de operare? Nu este un cerc vicios aici?

Cred ca o sa ajungem in curand la procesoare "Vista-only compatible". Microsoft are un viitor maaaare...

[/]

29. June 2007 - 10:31

beranger

Raspuns: Procesoare Intel Core 2 Duo "peticite"

Ah, cred ca sunt singurul paranoic interesat de subiect (cu exceptia lui Theo de Raadt), dar pentru ca stirile au continuat, iata un update cu ce s-a mai scris si comentat pe aceasta tema.

— Slashdot: Theo de Raadt Details Intel Core 2 Bugs

Un comentariu:

Quote:

Well, in these days of fast-paced business, business at the blink of an eye, at the speed of light, at the speed of spooky action at distance kinda speed, it’s normal that companies would release products prematurely and then patch later. Thankfully, software is very easy to patch post-release.
Now, the only thing left to do, is someone tell Intel that they’re selling hardware.

— Theo de Raadt:

Quote:

Various developers are busy implimenting workarounds for serious bugs in Intel's Core 2 cpu.
These processors are buggy as hell, and some of these bugs don't just cause development/debugging problems, but will *ASSUREDLY* be exploitable from userland code.

As is typical, BIOS vendors will be very late providing workarounds / fixes for these processors bugs. Some bugs are unfixable and cannot be worked around. Intel only provides detailed fixes to BIOS vendors and large operating system groups. Open Source operating systems are largely left in the cold.

Full (current) errata from Intel: http://download.intel.com/design/processor/specupdt/31327914.pdf

- We bet there are many more errata not yet announced -- every month this file gets larger.
- Intel understates the impact of these erraata very significantly. Almost all operating systems will run into these bugs.
- Basically the MMU simply does not operate as specified/implimented in previous generations of x86 hardware. It is not just buggy, but Intel has gone further and defined "new ways to handle page tables" (see page 58).
- Some of these bugs are along the lines of "buffer overflow"; where a write-protect or non-execute bit for a page table entry is ignored. Others are floating point instruction non-coherencies, or memory corruptions -- outside of the range of permitted writing for the process -- running common instruction sequences.
- All of this is just unbelievable to many of us.

An easier summary document for some people to read: http://www.geek.com/images/geeknews/2006Jan/core_duo_errata__2006_01_21__full.gif

... As I said before, hiding in this list are 20-30 bugs that cannot be worked around by operating systems, and will be potentially exploitable. I would bet a lot of money that at least 2-3 of them are.

For instance, AI90 is exploitable on some operating systems (but not OpenBSD running default binaries).

At this time, I cannot recommend purchase of any machines based on the Intel Core 2 until these issues are dealt with (which I suspect will take more than a year). Intel must become more transparent.

(While here, I would like to say that AMD is becoming less helpful day by day towards open source operating systems too, perhaps because their serious errata lists are growing rapidly too).

— Pe Linus Torvalds il doare in basca (as fi indicat un organ adevarat, dar suntem pe un forum):

Quote:

>How significant were the TLB handling changes?
I'd say: "Totally insignificant".

The biggest problem is that Intel should just have documented the TLB behavior better. The Core 2 changes are kind of gray area, and the old documentation simply didn't talk about the higher-level page table structures and the caching rules for them.
So that part is just a good clarification, and while it could be called a "bug" just because older CPU's didn't do that caching, I don't think it's an errata per se.

Of course, if you depended on it not happening (and a lot of people did), it's painful. But it really does make the architecture definition better and clearer.

(I don't think Linux needed any software changes at all for the TLB semantics clarification, although that was largely just due to luck - we had mis-used the TLB earlier, and fixing that software bug we rewrote the page table handling to be more robust, which means that the spec update from Intel didn't affect us at all, afaik).

Dintr-un reply:

Quote:

If you really want to know... http://strombergson.com/kryptoblog/?p=311
... Basically, the new Celeron seems to have a separate memory and process manager that can hide the thread and memory that does ... stuff.

But the chip is creepier than that. If I am understanding Strvmbergson correctly, this chip is the first step in a brave new world where you have no clue what really goes on when you buy a chip.

— The Register: Intel releases Core 2 chip Bios fix

— Comentarii pe OSNews: De Raadt Bugs in Intel Core 2 Duo

— ZDNet: OpenBSD founder: Intel leaves open-source out in the cold

— Matasano Chargen: Theo de Raadt: Intel CORE 2 Bugs “Assuredly” Exploitable From Userland