Windows is one of the largest pieces of engineering that exist. It is an incredibly complex operating system, full of code for all kinds of situations and events; either to add compatibility with certain hardware, or to gain new functions, over the decades this source code has grown at a great pace.
Of course, not all the added code has obvious utility. Many complain when the system forces us to update and we do not notice the difference; it may be because it is a patch to fix a bug, or a function that we do not use. Even for the programmers themselves, there are patches that do not make much sense.
Microsoft programmer Raymond Chen has shared one of the most curious cases, a patch that is still in the kernel source code of Windows; despite the fact that everyone agrees that it is useless.
The code calls a function called "invd", which invalidates the contents of the processor cache; This is a small memory that the CPUs have for the instructions and data that will be used in the next operations. Therefore, this function effectively clears the cache and forces the processor to refill it.
The really striking is the reason to call this function: by gamma rays. According to the comment left by the official programmer, the function is called in case some gamma rays affected the bits stored in the cache. In this way, possible problems are avoided if the processor tries to use the corrupted bits.
Not to say that this is an unnecessary protection, but the funniest thing is that it is also poorly implemented. Gamma rays are not usually a problem; It is true that they can affect electronics, but they occur mainly in space and the atmosphere absorbs them.
Not only that, but in the unlikely event that a gamma ray hit our computer, RAM would be more vulnerable; It would make more sense to include code to prevent corruption of RAM.
Of course, a similar function might be useful in space; but this code was for the Windows version for consumers, not for embedded systems like those that use satellites, for example.
Even Microsoft knew how unnecessary it was
At Microsoft already knew all this, and that the patch was quite useless. The only reason for the patch is that a processor manufacturer asked for it. "I'm serious," wrote the original programmer, who also could not believe what he was doing.
; Invalidate the processor cache so that any gamma stray
; 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
This is possibly the most useless patch Windows has received. And that is already saying. As proof, just three weeks after implementing it, the instruction was blocked and is no longer executed; although the code is still present, just in case one day you have to fight against gamma rays that corrupt processors, Chen jokes.
Date update on 2018-11-26. Date published on 2018-11-26. Category: windows Author: Oscar olg Fuente: elespanol