Comment by bombcar
5 years ago
Yeah, I was thinking more of architecture errors where the solution is “modify the compiler so that code isn’t called” - though some may allow microcode updates.
The various spec-ex workarounds actually matter more on things like cloud servers than they do on dedicated/controlled hardware.
When microcode is so small (2K according [0]) how can it work to enable/disable specific instructions, or even change how they work?
[0] https://en.wikipedia.org/wiki/Intel_Microcode
If I'm reading that page right, the update is 2 kB but it does not contain a full set of microcode, only some sort of patch e.g. only for the instructions that need fixes.
Interesting. So a CPU at version N is updated by a sequence of N patches applied in order, where each patch is a pair of location and code-as-data, plus noise (gotta confuse the competition, and hackers I guess).
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