Re: Handling PCI/ROM space

[Jeremy Fitzhardinge <jeremy@goop.org>]

Zachary Amsden wrote:
> Probably a config file difference - GOBIOS vs GODIRECT.
>
> These patches look fine, although is there a more general solution?  
> Like bypassing the whole PCI ROM probing entirely?  We don't really 
> want to use the PCI ROM here either, although we have a slightly worse 
> problem - the pages are mapped and do have a PCI ROM.  Perhaps 
> paravirt-ops should be able to flip a global switch to disable this 
> (perhaps already there?).

There's a pci_probe variable, which has a bitmask of which PCI access 
methods to use; if you mask out PCI_PROBE_BIOS then it won't bother.  I 
considered doing this, but it wasn't clear to me where this actually get 
set up (it's a bit diffuse), and whether to add a new pv_op hook 
intercept this.

I also thought that we don't necessarily want to unconditionally disable 
PCI access for paravirt guests since even an unprivileged guest may have 
a raw device exported to it, and we don't want to add too many special 
cases when dom0 is migrated to operate in the pv_op world.  So it seemed 
more correct to actually allow the probe but deal with unmapped pci ROM 
space.

    J