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A comment on Multiple OS Vendors Release Security Patches After Misinterpreting Intel Docs. Parent comment

Re:Multiple OS Vendors Release Security Patches After Misint... by simion314 on Thursday May 10, 2018 @09:23AM (#17038582)
If you can't trust the CPU documentation how can you test that addition works? even if you could test all possible combinations of terms to add and verify the results there may be a hidden flag somewhere that when flipped will change how addition works.
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Re:Multiple OS Vendors Release Security Patches After Misint... by Tobba_ on Thursday May 10, 2018 @11:09AM (#17039521)
On that subject, I'm curious whether there is any CPU out there that sets the overflow flag incorrectly when computing (-1) - n when n is the most negative number (which negates to itself, so implementing subtraction by simply negating the RHS and adding will screw up the flags).
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Re:Multiple OS Vendors Release Security Patches After Misint... by Vogtinator on Saturday May 12, 2018 @06:13PM (#17056278)
The ARM ARM documents sub(left, right, no carry) as add(left, ~right, carry set), which is also the most straightforward implementation if you have to account for carry anyway.
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