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Recent versions of Debian require a 686. https://www.debian.org/releases/stable/i386/ch02s01.en.html#idm272 https://www.debian.org/releases/stable/i386/ch02s01

• quotemstr 6y ago
  Would it be feasible to just build a Debian image for the i486? Few packages should depend on something newer.
  • asveikau 6y ago
    I don't know offhand what instructions were introduced in Pentium or later. Doing some googling... 486 had cmpxchg, that's good. Seems it didn't have rdtsc. It's not out of the question, I might say even pretty common, for user mode code to use that one via inline asm to implement a timer. Obviously no SIMD instructions. If they say they're supporting 686 or better they might have some compiler flags that depend on mmx or similar? SSE came late to P6.
  • giantrobot 6y ago
    Since the modern Linux kernel doesn't make any promises of 486 support there's very likely plenty of places inline assembly uses instructions unavailable on a 486. So even if you compiled it with strict -march i486 you'd end up with unsupported instructions. Modern GCC also doesn't like emitting strict i386 or i486 code anymore so you'd be likely to end up with unsupported instructions even without any inline assembly.
• znpy 6y ago
  also, this video features a 486 cpu because linux dropped 386 support a while ago. https://www.zdnet.com/article/good-bye-386-linux-to-drop-support-for-i386-chips-with-next-major-release/ https://www.zdnet.com/article/good-bye-386-linux-to-drop-sup...
  • pan69 6y ago
    I was always under the impression that Linux 386 simply meant 32 bit support. So, no 386 support would mean no 32 bit support rather than the 386 specifically.
    • Symbiote 6y ago
      No, that's x86. They dropped 386 support, but a 486 still works.
    • II2II 6y ago
      I have seen i386 being used in a couple of contexts. For example, Debian uses it to refer to the 32-bit port[1]. It also seemed to be used when various Linux distributions built Pentium optimized packages when that became a thing. In that case 386 would be used for earlier 32-bit processors and 686 would be used for later 32-bit processors. So the nomenclature is not always clear. [1] https://www.debian.org/releases/stable/i386/ https://www.debian.org/releases/stable/i386/
  • twoodfin 6y ago
    Anyone know what in particular the 486SX had that the 386 didn’t to make keeping only the former alive practical? Unfortunately the kernel mailing list link in the zdnet article appears to be rotted away.
    • BruiseLee 6y ago
      I believe 386 did not have certain "atomic" instructions like CMPXCHG or XADD. So in order to support 386, the kernel had to have special versions of all locking primitives just for 386.
    • projektfu 6y ago
      Basic multitasking (CMPXCHG) and cache management instructions.
    • jabl 6y ago
      Here's a working link: http://lkml.iu.edu/hypermail/linux/kernel/1212.1/01152.html http://lkml.iu.edu/hypermail/linux/kernel/1212.1/01152.html From that link: x86, 386 removal: Remove CONFIG_CMPXCHG x86, 386 removal: Remove CONFIG_XADD x86, 386 removal: Remove CONFIG_BSWAP x86, 386 removal: Remove CONFIG_INVLPG x86, 386 removal: Remove CONFIG_X86_WP_WORKS_OK x86, 386 removal: Remove CONFIG_X86_POPAD_OK