Intel iapx 432 manual Winjxw ATlRIBUlES

iAPX 432 Interface Processor Architecture Reference Manual

3-1.WINJX)W ATl'RIBUl'ES

Each window has a set of attributes which define its state at a given rnanent; these are sumnarized in table 3-1. The IP sets the attributes of all five windows when it performs processor qualification. The attributes of the control windcw are obtained

from values recorded in the processor object. Processor qualification closes windows 0-3.

Processor qualification is performed explicitly when the Interface Processor responds to a "suspem am fully requalify processor"

interprocessor communication (IPC). The IP performs processor qualification :implicitly in response to the startup IPC it receives during system initialization (see appendix E). Thus, window 4 may be made to cane' up with any set of attributes by encoding the desired values in the processor object image that is loaded during initialization.

Having entered logical reference mode,· the I/O controller can change the attributes of windows 0-3 with the AL'lER MAP AND SELECl' DATA SEGiENr function. Unlike the other windows, window 4' s attributes

may not be altered during normal execution; its attributes are fixed once logical node is entered. The IP can be conmanded to reenter physical mode by a special IPC fran a 432 processor, irx::luding itself. Any processor with an access descriptor for a processor object with broadcast rights can sem the "enter physical J'l'k:X1e" IPC to all processors in the 432 system. GDPs ignore this interprocessor message.

WINOOW STATUS

A window must be ~ for it to be used to transfer data. An open window establishes an active mapping between a set of addresses in the Peripheral Subsystem and an object in the 432 system; other attributes provide further mapping information.

A closed window is inactive, and has no other attr ibutes. A window may be closed to prevent further access to an obj ect, or to change the attributes of a window. Closing a window which overlays PS memory (see OVERLAY in this section) enables access to the PS memory.

When a window detects a fault, the IP records in 432 menory the fault information describing the circumstance, changes the state of the affected window to the faulted state, and interrupts the AP. In the faulted state the IPwill continue to acknowledge transfers through the window though no data will actually be nnved to/from the 432 system (see the description of XACK/ am NAK/ in the Intel iAPX 43203 Interface Processor Data Sheet, Order Number 171874). This state is entered to allow DMA-type controllers to proceed safely in the presence of a window fault. .

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