First, let me say that I strongly agree with the people who told the
original poster that he shouldn't whack on PCI configuration I/O ports
Second, let me point out that the CF8/CFC mechanism that is so prevalent on
PCs is hardly architecturally required on IA-64, particularly since all
(legal) PCI configuration access, even by the OS, goes through the SAL,
which a firmware layer. So IA-64 machines are completely free to implement
PCI configuration space through absolutely any hardware mechanism. They
could map it linearly in physical memory space, if they cared to. And they
probably will with future chipsets, as that's what PCI-Express requires. Go
through the OS layers that work on x86 and you'll automatically go through
the right firmware layers on IA-64.
Third, several people have mused on the general nature of I/O space on
IA-64. So here's some actual information.
1) There is no processor bus cycle for I/O space. (But there isn't one for
Athlon or Opteron either, so that's nothing new.)
2) I/O is mapped into linear physical memory address space. (Again, it is
on Athlon or Opteron, too.)
3) There are special processor instructions that implement I/O, just like
on x86. They look at a base address register inside the processor and then
convert the instruction into a memory fetch with the proper barriers.
(Again, this is very much like an Athlon or an Opteron.)
4) The memory base is chipset-specific, and it's reasonably difficult to
5) The I/O is mapped sparsely into memory space, with small blocks of ports
mapped into individual memory pages, making it much, much easier to
implement a DOS emulator with I/O space protection, since you can put the
protection into the page tables.
Windows Base Kernel Team
This posting is provided "AS IS" with no warranties, and confers no rights.
"Ed in Calif" wrote in message news:xxxxx@ntdev...
> There is no IO but I think the IO space is somewhere
> in the main memory map. But I am still trying to figure
> that out.
> ----- Original Message -----
> From: "Maxim S. Shatskih"
> To: "Windows System Software Devs Interest List"
> Sent: Thursday, January 15, 2004 8:10 AM
> Subject: Re: [ntdev] How to build Port IO driver for IA-64?
> > > IO space. So how do I access the configuration space
> > > on a PCI card when running a 64 bit OS? Is there an example
> > > somewhere of how the IA-64 systems access IO addresses?
> > I think such a task can be completely impossible, except by !pci command
> in the
> > kernel debugger.
> > Is there any "IO addresses" on IA-64 at all?
> > Maxim Shatskih, Windows DDK MVP
> > StorageCraft Corporation
> > firstname.lastname@example.org
> > http://www.storagecraft.com
> > ---
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