5 ms·
As far as I can tell EXDAMS was never implemented. The RAND EXDAMS memo is more of a thought experiment than anything else. Getting reverse-execution debugging
by roca 9y ago
As far as I can tell EXDAMS was never implemented. The RAND EXDAMS memo is more of a thought experiment than anything else.
Getting reverse-execution debugging to work adequately at scale is difficult. gdb's approach doesn't scale at all. I dispute that reversible debugging has been "generally practical for two or three decades"; as far as I know the first practical products were UndoDB and VMWare.
- mncharity 9y ago> EXDAMS [...] a thought experiment Ah, good point. > "generally practical for two or three decades" [...] the first practical products I was thinking of "we now know how to do this" (snapshot and replay (and input log)), rather than "and it's a product". Which seems sometimes valid, and sometimes not. We know how to make a 4K/eye VR HMD with existing parts, and it's simply a market failure that one's not on my desk. But for other things, "know how to do it, sort of, in a lab" and "know how to do it, practically, for real" can be greatly separated in time and effort. > first practical products were UndoDB and VMWare My very fuzzy recollection is DEC alpha had a reversible debugger in the late 1990's? - but I'm not finding it.
- mncharity 9y ago> As far as I can tell EXDAMS was never implemented. The RAND EXDAMS memo is more of a thought experiment than anything else. The memo[1] mentions > Since EXDAMS is currently being debugged and is not operational, no performance statistics are available. [p12] Suggesting implementation was attempted, though perhaps not successfully? [1] "EXDAMS: extendable debugging and monitoring system" Memo RM-5772-ARPA APRIL 1969 http://www.dtic.mil/get-tr-doc/pdf?AD=AD0686373 http://www.dtic.mil/get-tr-doc/pdf?AD=AD0686373