Introduction to Gates

How the Jumpee Receives Control

Jump Action

{arcane}Pathologies

{nonref}Design Notes

Programming Notes {see also (p3,domprgnotes) and (p3,bhmonitor)}

When you accept a parameter string you must know that the pages at the specified addresses will be real when you are jumped to. Under common circumstances addresses do not have pages disappear out from under them and it will suffice to access the page just before a jump. Segment keepers have been invented that will cause pages to disappear however. {See (p3,expseg).}

This situation makes it desirable to specify when possible that the logic of the keeper of a segment will ensure that a page will always exist at an address in the segment after it has once existed at that address.

The two segment keepers that are available now very nearly have that attribute. Unfortunately they both rely on the trick of momentarily making the segment disappear while the SSC of the top segment node is being increased. It appears that a small change to those keepers will give them this attribute.