Re: multi-domain PCI and sysfs

[Jon Smirl <jonsmirl@gmail.com>]

On Mon, 6 Sep 2004 02:40:58 +0100, Matthew Wilcox <willy@debian.org> wrote:
> > When implementing the VGA control I'm running into the problem that
> > there is no root node in sysfs for the top of a domain. I need a
> > domain node to attach an attribute disabling all VGA devices in the
> > domain. In the zx1 diagram I could have vga devices on any of the
> > PCI-X or AGP buses.
> 
> Why would it be a problem if the attribute is per-bus, as it is right now?
> see bus->bridge_ctl (PCI_BRIDGE_CTL_VGA)
> 
> Actually, they're sparsely numbered to allow for people plugging in pci-pci
> bridges on cards, so:
> 
> $ ls -1 /sys/devices/
> pci0000:00
> pci0000:80
> pci0000:a0
> pci0000:c0
> platform
> system

How many active VGA devices can I have in this system 1 or 4? If the
answer is 4, how do I independently address each VGA card? If the
answer is one, you can see why I want a pci0000 node to hold the
attribute for turning it off and on.

How many simultaneous VGA devices does this system allow?

ppc32:
jbarnes@mill:~$ ls -l /sys/devices
total 0
drwxr-xr-x   5 root root 0 Sep  4 13:37 pci0000:00/
drwxr-xr-x  13 root root 0 Sep  4 13:37 pci0001:01/
drwxr-xr-x   7 root root 0 Sep  4 13:37 pci0002:06/
drwxr-xr-x   3 root root 0 Sep  4 13:37 platform/
drwxr-xr-x   4 root root 0 Sep  4 13:37 system/
drwxr-xr-x   5 root root 0 Sep  4 13:37 uni-n-i2c/

I would think it is three active devices.

Does a PCI domain imply separate PCI IO address spaces, or does it
just mean separate PCI Config spaces?

Can an x86 machine use separate PCI IO address spaces?

-- 
Jon Smirl
jonsmirl@gmail.com