RE: Device at address 0

["O'Shea, David J" <david.j.oshea@intel.com>]

The Specification doesn't prevent a base address of 0.
The enable disable is really in the command register for
decode of I/O or memory.

However, many implementations improperly make the assumption
that 0 in the basereg also means disabled.  In practice, the
mistake doesn't usually amount to much, since most Intel or
even most "non-Intel" systems generally have memory located
at address 0, and usually preclude I/O or memory assignments
to PCI addresses at this address.  But that's just a "system"
architecture result, NOT a result of the PCI specification 
itself.

David O'Shea
Intel Corp.


-----Original Message-----
From: Parampalli, Niranjana [mailto:niranjana.parampalli@intel.com]
Sent: Thursday, August 01, 2002 9:23 AM
To: 'pci-sig@znyx.com'
Subject: Device at address 0



I am looking at a PCI implementation which 
requires BaseAddressReg to be non zero value
(does not respond if located at 0). I could not
find anything relevant in PCI (2.3) that precludes
relocating device to Address 0. Any thoughts?

Thanks,
-n.p.