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That Time The Windows Kernel Fought Gamma Rays Corrupting Its Processor Cache (microsoft.com)

Posted by EditorDavid on from the cosmic-coding dept.

Long-time Microsoft programmer Raymond Chen recently shared a memory about an unusual single-line instruction that was once added into the Windows kernel code -- accompanied by an "incredulous" comment from the Microsoft programmer who added it:

;
; Invalidate the processor cache so that any stray gamma
; rays (I'm serious) that may have flipped cache bits
; while in S1 will be ignored.
;
; Honestly. The processor manufacturer asked for this.
; I'm serious.
invd

"Less than three weeks later, the INVD instruction was commented out," writes Chen. "But the comment block remains.

"In case we decide to resume trying to deal with gamma rays corrupting the the processor cache, I guess."

4 of 166 comments (clear)

  1. Microsoft's never doing any military or space work by johnjones · · Score: 3, Informative

    preparing your software for failures in hardware due to common problems such as radiation might be a good idea...

    This is why some firms/states would not trust microsoft to critical functions....

  2. This is not that crazy... by Anonymous Coward · · Score: 0, Informative

    I once had to debug a situation where an opto-coupler had been changed out from a part that had black plastic to a part that had white plastic. The difference in the opacity of the casing was enough to cause a larger drift when in the sunlight. This is not as crazy as it sounds...

  3. Re:Microsoft's never doing any military or space w by Anonymous Coward · · Score: 3, Informative

    Reading the full story, it's rather strongly implied that it was actually a workaround for a bug in the processor which the manufacturer hadn't found yet, and was blaming on cosmic rays.

  4. Laptop aboard the International Space Station ? by Laxator2 · · Score: 5, Informative

    I think they use laptops on the International Space Station and there you are not protected from cosmic rays by the blanket of the Earth's atmosphere. Just read up on the phosphenes experienced by the astronauts as they try to go to sleep.

    Not sure if "gamma rays" is the correct term here, as high-energy protons are most likely to create a local change in electric charge density. With modern processors being built ont the 14 nanometres process this becones a serious problem. All the processors that are used in spacecraft and control vital functions are radiation-hardened. That usually means older fabrication processes (wider paths reduce the probability of cross-talk) and amorphous silicon (a monocrystal can sustain permanent damage from a particle of high enough energy)

    Overall, it does make sense if it is meant to be used in space.