| Title | Can't access memory without hitting MPS protection barrier. |
| Status | closed |
| Priority | essential |
| Assigned user | David Jones |
| Organization | Ravenbrook |
| Description | In order to investigate the Win2K / Office XP problem (job000812) Configura would like to have the MPS lift all memory protection barriers that it is using. They are happy that this can only when when the arena is parked. They understand that this will impact performance and is intended for debugging. This is part of the problem described in job000812 |
| Analysis | We should provide a function to call (when the arena is parked) that removes all memory protection. In principle this is quite easy to do, just set the segment's summary to RefSetUNIV for all the segments in the arena. Possibly just all scannable / protectable segments. Testing: A suitable test might be to use a Structured Exception Handler to see whether a page has been protected. This is not portable of course. A more portable test might be to print out how long an acccess takes though this is more subjective. The test exposet0.c takes the former approach and uses SEH. Design and implementation notes: Arranges to park arena so no requirement to call it only when parked already. Call SegSetSummary(_, RefSetUNIV) on all scannable segments. |
| How found | customer |
| Evidence | https://info.ravenbrook.com/mail/2003/10/29/16-10-08/0/ |
| Observed in | 1.101.0 |
| Created by | David Jones |
| Created on | 2003-11-04 09:51:32 |
| Last modified by | Gareth Rees |
| Last modified on | 2013-03-19 12:11:33 |
| History | 2003-11-04 DRJ created 2003-11-04 DRJ closed |
| Change | Effect | Date | User | Description |
|---|---|---|---|---|
| 62949 | closed | 2003-11-04 12:34:54 | David Jones | MPS: implementing mps_arena_expose |