4 ms·

Hidden Debug Mode Found In AMD Processors

30 points by nitam 16y ago

limmeau 16y ago
Probably slashdotted -- I get a database error.
- rbanffy 16y ago
  Indeed: http://hardware.slashdot.org/story/10/11/12/047243/Hidden-Debug-Mode-Found-In-AMD-Processors http://hardware.slashdot.org/story/10/11/12/047243/Hidden-De...
  - limmeau 16y ago
    Apparently, Slashdot reader TheRaven64 has read the story. He summarizes it: http://hardware.slashdot.org/comments.pl?sid=1865066&cid=34206216 http://hardware.slashdot.org/comments.pl?sid=1865066&cid... (tldr: it's about DR0 working on more than one word)
dredge 16y ago
Google's cache has a forum thread on the site, which I suspect led to the creation of the page linked above (which isn't yet cached) http://www.google.com/search?q=cache:www.woodmann.com/forum/archive/index.php/t-13891.html http://www.google.com/search?q=cache:www.woodmann.com/forum/...
makmanalp 16y ago
Hah, I can't believe woodmann.com is still alive. I used to read through fravia's website's mirror there.
- makmanalp 16y ago
  Downvoted? What's wrong with what I said? I appreciated that site.
  - ars 16y ago
    Because it has nothing to do with the topic, and especially because it doesn't add anything to the discussion.
    - Natsu 16y ago
      Well, fravia was a student of +ORC and a reverse engineer who put a lot of information out there about reverse engineering at a time when there wasn't a lot out there (i.e. 10+ years ago). I guess he was just going for nostalgia, but I admit to being surprised that people are still mirroring that. I've only had to reverse a few things, but I have to say that that old information is still good, because it wasn't about specific technology, but it was a more general sort of reasoning backwards that allowed you to infer the inner workings of something by looking at it from the outside. Even when I'm not trying to reverse something, I find it useful: by reasoning about how things probably work internally, I can sometimes discover features that no one bothered to document or things like that.
daeken 16y ago
Anyone happen to know if this passes cleanly through AMD-V? There are a few really cool debugging facilities on modern x86 processors (e.g. branch-wise versus instruction-wise stepping) that aren't handled in any VM that I know of.
JoachimSchipper 16y ago
Also see http://news.ycombinator.com/item?id=1897583 http://news.ycombinator.com/item?id=1897583.

30 points by nitam 16y ago

limmeau 16y ago

Probably slashdotted -- I get a database error.

rbanffy 16y ago
Indeed: http://hardware.slashdot.org/story/10/11/12/047243/Hidden-Debug-Mode-Found-In-AMD-Processors http://hardware.slashdot.org/story/10/11/12/047243/Hidden-De...
- limmeau 16y ago
  Apparently, Slashdot reader TheRaven64 has read the story. He summarizes it: http://hardware.slashdot.org/comments.pl?sid=1865066&cid=34206216 http://hardware.slashdot.org/comments.pl?sid=1865066&cid... (tldr: it's about DR0 working on more than one word)

dredge 16y ago

Google's cache has a forum thread on the site, which I suspect led to the creation of the page linked above (which isn't yet cached) http://www.google.com/search?q=cache:www.woodmann.com/forum/archive/index.php/t-13891.html http://www.google.com/search?q=cache:www.woodmann.com/forum/...

makmanalp 16y ago

Hah, I can't believe woodmann.com is still alive. I used to read through fravia's website's mirror there.

makmanalp 16y ago
Downvoted? What's wrong with what I said? I appreciated that site.
- ars 16y ago
  Because it has nothing to do with the topic, and especially because it doesn't add anything to the discussion.
  - Natsu 16y ago
    Well, fravia was a student of +ORC and a reverse engineer who put a lot of information out there about reverse engineering at a time when there wasn't a lot out there (i.e. 10+ years ago). I guess he was just going for nostalgia, but I admit to being surprised that people are still mirroring that. I've only had to reverse a few things, but I have to say that that old information is still good, because it wasn't about specific technology, but it was a more general sort of reasoning backwards that allowed you to infer the inner workings of something by looking at it from the outside. Even when I'm not trying to reverse something, I find it useful: by reasoning about how things probably work internally, I can sometimes discover features that no one bothered to document or things like that.

daeken 16y ago

Anyone happen to know if this passes cleanly through AMD-V? There are a few really cool debugging facilities on modern x86 processors (e.g. branch-wise versus instruction-wise stepping) that aren't handled in any VM that I know of.

JoachimSchipper 16y ago

Also see http://news.ycombinator.com/item?id=1897583 http://news.ycombinator.com/item?id=1897583.