Using IARQD — The page status interface routine
If you are writing a program that dumps virtual storage and you need to determine where the virtual storage pages of an address space or of a data space reside, use the Page Status Interface Routine (IARQD).
Before using IARQD, you must understand the types of pages managed
in virtual storage and how these pages might be managed through the
paging hierarchy. For additional information, see:
When you invoke IARQD, a search begins for a page location and status. This search begins at an address that you provide, and continues for the number of pages you specify unless you reach a change in the page status or the end of storage first.
The requirements for the caller are:
| Environmental factor | Requirement |
|---|---|
| Minimum authorization: | Supervisor state with PSW key 0 |
| Dispatchable unit mode: | Task or SRB |
| Cross memory mode: | PASN=HASN=SASN |
| AMODE: | 31-bit |
| ASC mode: | Primary |
| Interrupt status: | Enabled for I/O and external interrupts |
| Locks: | No SPIN locks |
| Control parameters: | The parameter list must be in non-pageable storage in the caller's primary address space. |
There are 4 steps involved in using this interface:
- Decide which of the 2 entry points you want to use, IARQDUMP or IARQDSPD.
- Obtain storage and load register 1 with the address of the parameter list
- Use NUCLKUP to find the address of the entry point you want to use
- Invoke the entry point and evaluate the returned information
- Return codes
- Reason codes (possibly)
- Delimiter page