Who is stomping PCI config space?

[Benjamin Herrenschmidt]

> If you want to access these cards from inside your 
> kernel you could just check if they are enabled before 
> you do and enable them if they aren't. 
> This works as long as you can be sure nobody else will 
> access legacy resources from anywhere else - this may 
> be difficult if you have a machine with more than one 
> CPU, if you have more than one userland process that 
> may want to access the HW.
> You should make sure to restore the state before you 
> return.

Saving/restoring state doesn't help because of the SMP case.

> As a note on the side: 
> The Xserver doesn't 'stomp' over PCI config space any 
> more without telling the kernel: The code which does 
> direct PIO banging for config space access doesn't 
> get used any more unless the user explicitely *asks*
> for it. 
> The option to do so is well hidden from the user.
> This has been this way since X.Org 6.8.0 - I didn't 
> change this for 6.7.0 for lack of testing.
> 
> Egbert.
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-- 
Benjamin Herrenschmidt <benh at kernel.crashing.org>