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posted by
cmn32480
on Wednesday May 23 2018, @06:47PM
from the your-computer-is-not-a-fast-PDP-11 dept.
from the your-computer-is-not-a-fast-PDP-11 dept.
Very interesting article at the IEEE ACM by David Chisnall.
In the wake of the recent Meltdown and Spectre vulnerabilities, it's worth spending some time looking at root causes. Both of these vulnerabilities involved processors speculatively executing instructions past some kind of access check and allowing the attacker to observe the results via a side channel. The features that led to these vulnerabilities, along with several others, were added to let C programmers continue to believe they were programming in a low-level language, when this hasn't been the case for decades.
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(Score: 5, Insightful) by Lester on Wednesday May 23 2018, @07:39PM (2 children)
Yes it was a low level language for PDP11. And it is still a low level language for POSIX.
The author of the article says that many problems of current processors is trying to make C programmers believe that it is a low level language. I'l fix it for him: Many problems of current processors is trying to make C programmers believe that they are running on a real processor not a low level emulator.
That is like saying that Windows is not an operating system because it is able to run on Virtual Machine
C is a low level language running on a simplified processor
(Score: 3, Informative) by crafoo on Wednesday May 23 2018, @08:17PM
Thank you. You said this much better than I did. It was really quite an impressive trick, taking control of the hardware away from the owner without many even noticing what was going on. But they did it, and here we are.
(Score: 2) by qzm on Wednesday May 23 2018, @08:44PM
What has happened had nothing to do with C, high or low level. They obviously have no actual experience of the situation.
The problem is caused by the desire for high performance and backwards compatibility.
Absolutely nothing directly to do with C. There is nothing in C that would require any of this.
Mostly they appear to be working on the preemie that C is old, and 8086 architecture I is old, so C must control that architecture, which is just stupid.
C could just add easily target the internal physical architecture of it was exposed.
Im sure they have done pretty language they think is magically better, but this cart they are pushing has no wheels.