Timeline for What 386-specific features did Linux use?
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16 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 28, 2023 at 9:16 | comment | added | JeremyP | The two most popular desktop operating systems are based on microkernel principles. However, the designers took the decision to put a lot of the services that should not be in the kernel back in the kernel for performance reasons. | |
| Feb 25, 2023 at 21:00 | vote | accept | rwallace | ||
| Feb 25, 2023 at 10:31 | answer | added | Stephen Kitt | timeline score: 17 | |
| Feb 25, 2023 at 4:36 | comment | added | user15022 | Micro-kernels did win. In the same sense that Betamax won :-) Better doesn't always mean winner. | |
| Feb 25, 2023 at 4:35 | comment | added | user15022 | I have a vague recollection (so it could in reality be a mis-recollection) that early 386 UNICES tended to use swapping (whole process spaces) rather than paging (4K pages within processes). Obviously, swapping an entire process in or out of memory is a costlier exercise than individual pages. Maybe that was one example of what was being discussed here. | |
| Feb 25, 2023 at 0:00 | comment | added | dave | re the link - Project MAC (Project on Mathematics and Computation) That's the first time I heard that expansion. I know: Man And Computer. Machine-Aided Cognition, Multiple-Access Computer. | |
| Feb 24, 2023 at 23:53 | comment | added | dave | Intel CPUs provide way more features than modern operating systems use. Linear addressing, paging, kernel/user modes, and caches for performance would be enough. Who needs segments, hardware "tasks", etc? To some extent you can call this least-common-denominator OS design; systems tied to one hardware base are no longer in fashion. | |
| Feb 24, 2023 at 20:05 | comment | added | davidbak | And that link to a Q&A I didn't know about kind of talks about why the switch was made to not do it too. | |
| Feb 24, 2023 at 19:51 | comment | added | rwallace | @davidbak Aha! Yes. I didn't know about TSS, but it looks like you're right. stackoverflow.com/questions/2711044/… first answer confirms. | |
| Feb 24, 2023 at 19:46 | comment | added | davidbak | (That actually might be a good question if the answer isn't available by a single web search I don't have time to do: At the very beginning the 386 Linux used Intel architecture task switching. Later it didn't. (Confirm that!) When did the switch occur and why?) | |
| Feb 24, 2023 at 19:38 | comment | added | davidbak | Interesting to note that some of the first comments Tanenbaum made in the (doubly-indirect linked "LINUX is Obsolete" chain) is that the debate is over, the science is settled, and microkernels have won. That hasn't stood the test of time and wasn't even arguably true then. | |
| Feb 24, 2023 at 19:33 | comment | added | davidbak | HInt may be right there in the original Torvalds email where he says he's using 386 task switching. That right there is so 386 specific - and has such implications throughout low-level facilities like interrupt handling - that its unlikely to have been used by any other OS ported to the 386. And as for native OSes to the 386 - perhaps Windows? - again it would have been hard for them to support two completely different models - 286 vs 386 - but also it was quickly discovered that native x86 task switching was slower than conventional alternatives for what needed to be done. | |
| Feb 24, 2023 at 19:32 | comment | added | Jeff Zeitlin | Indeed - but even though their dominance wasn't as complete as it eventually became (up until a comparatively short time ago), the Intel iapx family of processors was definitely dominant on the desktop - possibly because of cost, but I wasn't as plugged in to the industry then as I am now. | |
| Feb 24, 2023 at 19:23 | comment | added | rwallace | @JeffZeitlin Maybe, but every other serious CPU family at the time had 32-bit linear addressing as the only mode, so that would make Linux more not less portable. | |
| Feb 24, 2023 at 18:53 | comment | added | Jeff Zeitlin | I won't swear to it, but at the time, Linux may have been the only OS that actually supported linear addressing, rather than the segment:offset addressing of previous Intel CPUs. | |
| Feb 24, 2023 at 18:21 | history | asked | rwallace | CC BY-SA 4.0 |