segments and Unix

[J.S.Shapiro]

> Suppose every data structure were in its own segment.

Phil, it's a useful debugging technique, and it does provide protection and
sharing, but in real code the overhead of swapping the segment registers in
and out would be too high. On the other hand, It ought to be possible
(designing on horseback now) to generate it that way with some appropriate
symbol table and go through and merge the segments you believe to eliminate
the segment register swaps.

The problem I see is getting into some nontrivial expression and thrashing
the segment registers around, along with the consequent changes
andinvalidations in the TLB. This would blow the mmu firmly out of the
water, if i remember the design right. It's been about 2 years since I
looked.

Jon Shapiro