Intel processors are dead, so I have an AMD question

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And the assumption is that AMD is very unlikely to have the Meltdown bug, unless it proven otherwise. Try harder, I think that you can understand it if you really try.

Since AMD has even admitted that they don't know if Meltdown affects their processors, do you know something that AMD doesn't?

There are known Meltdown exploits. They don't work on AMD. Simple.
And now, try a bit harder.

We believe AMD processors are not susceptible due to our use of privilege level protections within paging architecture and no mitigation is required.

There have also been questions about GPU architectures. AMD Radeon GPU architectures do not use speculative execution and thus are not susceptible to these threats.

It's not that simple. They haven't developed one that works on AMD processors yet.

It is possible that their chips are vulnerable and it is possible that they are not vulnerable. At present, nobody can honestly say they are or are not vulnerable because nobody knows whether or not they are vulnerable.

When someone develops one, we'll have a different talk.


It is possible that the teapot is there. At present, nobody can honestly say that the teapot is or is not there. /s
You totally missed the point again. Try harder.

In the case of the AMD chip, the chance of there being a Meltdown vulnerability may be one in a million.

You missed the point again. The Russel's teapot principle is not about chances.

So, your results so far:
Arrogance: A+
Reading comprehension: not passed
Logic: not passed

It is every bit about chances.

It's not. It's only about the burden of proof.
Try harder, I believe in you.

It is implicitly about odds.

No. Try harder.

List: openbsd-misc
Subject: Intel Core 2
From: Theo de Raadt <deraadt () cvs ! openbsd ! org>
Date: 2007-06-27 17:08:16
Message-ID: 200706271708.l5RH8GkK024621 () cvs ! openbsd ! org
[Download message RAW]

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/proces ... 327914.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/200 ... __full.gif

Note that some errata like AI65, AI79, AI43, AI39, AI90, AI99 scare
the hell out of us. Some of these are things that cannot be fixed in
running code, and some are things that every operating system will do
until about mid-2008, because that is how the MMU has always been
managed on all generations of Intel/AMD/whoeverelse hardware. Now
Intel is telling people to manage the MMU's TLB flushes in a new and
different way. Yet even if we do so, some of the errata listed are
unaffected by doing so.

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 be come 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).

Without zero chance that there could have been a china teapot in orbit, no burden of proof would have been required because a valid proof could not possibly exist.

Well, yes. However, the Russel's teapot principle is not about the comparison of the chances. It's about the burden of proof.

It sounds like you had a freshman logic course and flunked it.