It knows the physical address. It doesn't know the linear address. Which
means that it can't contain code (or rather, the code would have to be PIC
for no good reason - nasty for performance).
> 1b) user-space can look for the known page and read values from it, if
> it wants
It's not about reading values. The time offsets are completely useless if
the CPU doesn't support rdtsc. We want to export CODE, not data.
> 2) MAP_INHERIT can be used by user-space to implement
> machine-specific code.
Sure. MAP_INHERIT can be used for general-purpose things. But MAP_INHERIT
is not going to happen. It has security issues that you ignore,a dn it has
performance issues for process creation (we can't just completely break
down and re-build the page tables, we have to be careful). End of story.
It's a neat idea, but as I've said before, it sucks in real life.
Linus
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