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Shared Address Space for Local Functions On Multiple Adapters

IP.com Disclosure Number: IPCOM000119820D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 81K

Publishing Venue

IBM

Related People

Gyllenhammer, CR: AUTHOR [+2]

Abstract

There are times when it is desirable to use an adapter multiple times in a system. It is possible that there are addressable functions on the adapter that are meant to be used only by that specific device. These types of functions will be called Local functions.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Shared Address Space for Local Functions On Multiple Adapters

      There are times when it is desirable to use an adapter
multiple times in a system.  It is possible that there are
addressable functions on the adapter that are meant to be used only
by that specific device.  These types of functions will be called
Local functions.

      With the normal division of address space, each of these
addressable functions to be kept separate would have to be mapped to
a unique address range.  This, however, uses up system address space.

      A better solution is to make each "Card Specific" (Local)
function respond to the same address but only when the address is
produced by the card on which the function resides.  This allows the
function to take up only one address range and be used multiple
times.

      Let us assume, for this example, that Adapter 1 was made up of
two separate functions (these being Function A and Function B).  Let
us assume the following is also true:
      The system bus is used for communication among Function A,
Function B and the System.
      Function A can communicate with Function B and the entire
system so Function A is considered a System function.
      Function B only communicates with Function A on that adapter so
Function B is considered a Local function.

      Function A is placed in the System's address space because it
must communicate with the rest of the system.

      Function B, although it only communicates with Function A, is
placed on the System Bus.  It could have been placed there for any
n...