On 08/14/2007 02:47 PM, Peter Stuge wrote:
The CF8/CFC sequence can preserve CF8 port value. What other hardware state would be changed?
The bits that are changed in the device config space.
I cannot imagine why the OS would care about a couple of configuration bits in the SB.
Yup. Are you saying it is simply not possible to access PCI config space of a device from a device driver unless the driver is in fact part of the driver stack associated with that device?
Yes.
I suppose Microsoft considers that a feature?
Yes. They don't want one driver to mess with other devices.
But, on the other hand, there are a few applications that _do_. So how do they do it?
Using undocumented features is not uncommon in Windows.
we can make ourselves be part of the driver stack for the southbridge?
It sounds too painful.
Or maybe there is in fact a userspace API for PCI config access?
I doubt. It would be a huge security hole.
I am by no means a Windows API or WDM expert, then I'd already written the code. :p That world is a pretty strange place.
Lucky you... It is not a pleasure to write Windows code.
Regards,
Roman