RE: Device at address 0

["Parampalli, Niranjana" <niranjana.parampalli@intel.com>]

Wen,

Further down that paper (2.1 to 2.2 Change summary),
highlighting changes in Chapter 6 it says..
  "...Devices will not be allowed to request
   memory space below the 1 Meg (Software will
   continue to support requests from pre-2.2
   devices.)"

But then it did not make it 2.2, I guess!

-n.p.

-----Original Message-----
From: wen-king@myri.com [mailto:wen-king@myri.com]
Sent: Friday, August 02, 2002 3:21 PM
To: pci-sig@znyx.com
Subject: RE: Device at address 0


In PCI 2.1 spec, section 3.2.2 at the end of the text box titled
"Implementation Note: Device Address Space", the last sentence says: A
base address register does not contain a valid address when it is equal
to "0".

In PCI 2.2 spec, in the same section and same text box, the sentence is
removed.  If its removal means having an all-0 address is now valid, it
would means it is now impossible for a card to be simultaneously
compliant to 2.1 and 2.2.

What happened?  I must have missed something.  I searched the PCISIG
web site, and looked into "2.1 to 2.2 Change summary", and I don't see
a mention of this change.

PDF file on http://www.pcisig.com/specifications/conventional_pci

It says something about 3.2.2 being re-written for improved readability,
but nothing to imply any functional changes of that sort.  I wish I
could "diff" the electronic versions of the specs.

								- Wen