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> You could potentially work around this by building the new machine with enough memory that you can just start the "enhanced-mode universe" after the hairball

> You could potentially work around this by building the new machine with enough memory that you can just start the "enhanced-mode universe" after the hairball that exists in the bottom 64k. But if you wanted to offer a 128k or 256k machine, you can't afford to squander all that expensive RAM. And even still... That's exactly what PCs did with 386 . even today, if you boot on legacy bios mode, you get the same lower 1MiB address space and mappings

hakfoo 3y ago
I was thinking more specifically like https://www.phoronix.com/news/Linux-Always-Reserve-1MB https://www.phoronix.com/news/Linux-Always-Reserve-1MB Note that this was apparently a decision made in 2001. If you tried this in 1988, when 2Mb was an enormous machine, and you said to users "Yeah, only half of that will be allocated to user programs", that's not gonna fly.
- snvzz 3y ago
  Relative to this, the RISC-V platform specs are nice and clean. No segments, no "Conventional memory 640KB" or other such cruft.