Zachary Amsden wrote:
> "Who can discern his errors? Forgive my hidden faults."
In general that Book doesn't give much in the way of architectural
certainty. 3.12 IA32SDM isn't much better:
Whenever a page-directory or page-table entry is changed (including
when the present flag is set to zero), the operating-system must
immediately invalidate the corresponding entry in the TLB so that it
can be updated the next time the entry is referenced.
The parenthetic clause is annoyingly ambiguous: does it mean "when the
present flag is currently set to 0" or "when setting the present flag to
0"? The passive voice should always be avoided.
> Oh, wow. Unfortunately, the complexity isn't from how frequent or
> rare a kmapped PT access is, it is from it being there at all.
We'll see how it works out. What actually needs to do cross-process
pagetable manipulation? Fork? ptrace?
J
