You try to display a folder/directory listing with a file manager (say Ubuntu's Nautilus file manager/Windows' Explorer), so the file manager gets the OS to scan the file table for a list of files, and in turn access the files themselves in order to produce thumbnails. Say you have a defective external hard disk thanks to bad sectors (on the physical hard disk surface), which have affected a video file "Rickroll.avi" located on the bad areas. On newer versions the kernel will detect that error and restart the driver to a known good state.Ĭouple of extra points in my opinion/experience:Īnother hardware example (rather common) - Hard disk defects (bad sectors, controller failures, etc). On older versions of Windows an uncorrectable error would be fatal and the kernel would halt the computer with a "blue screen". One good example of this is the graphics driver. Recent versions of Windows moves a lot of the drivers from "kernel mode" where they run as part of the operating system and will crash/hang/freeze the computer in many cases if an error occurs, into "user mode" where they run more like an ordinary application that can be restared without affecting the rest of the computer. The most common is a driver that gets stuck in a loop and times out. Please note that there are many reasons for a "blue screen" and hardware error is just one. On Windows this will manifest itself as a "blue screen", on Linux you get a "kernel panic". When a problem like that appears and the kernel can not fix it it will crash the computer on purpose to protect the data in the computer as it can no longer guarantee its correctness. It's the operating system kernel that will try to work around the issue in the first example. The first case, where there's something wrong with the hardware, is much harder to avoid. There are plenty of methods to avoid situations like the latter, because that's all software, but it doesn't stop it happening occasionally, usually between unrelated software. If this happens in your operating system, your computer stops working. This sounds fine, but what happens if they don't let go of one resource before picking up the other? They both sit there each waiting for the resource they want and never get it. and at the same time Program C decides to use resource B. Program A then decides it needs to use resource D. There's also the concept of 'deadlock' in software: Say program A is running and is using resource B and program C is using resource D (these resources might be files or peripherals like the hard disk or video card). I would say "an infinite loop" but sometimes "a very, very long loop where nothing much changes" also counts.įor example, something may go wrong with the hardware, and the BIOS may try to work around the issue, but in so doing encounters the same problem, so the BIOS tries to work around the issue and in so doing encounters the same problem. Any one of a number of things could be happening, but they all come down to one particular general thing: The computer has become stuck in a state from which it cannot escape.
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