Re: [PATCH 16/16 v6] PCI: document the new PCI boot parameters

[Alexander Graf]

> > > > > If we do resource rebalance after system is up, do you think  
> > > > > there is any
> > > > > side effect or impact to other subsystem other than PCI (e.g.  
> > > > > MTRR)?
> > > > I don't think so.
> > > > > I haven't had much thinking on the dynamical resource rebalance.  
> > > > > If you
> > > > > have any idea about this, can you please suggest?
> > > > Yeah, it's going to be hard :)
> > > > We've thought about this in the past, and even Microsoft said it  
> > > > was
> > > > going to happen for Vista, but they realized in the end, like we  
> > > > did a
> > > > few years previously, that it would require full support of all PCI
> > > > drivers as well (if you rebalance stuff that is already bound to a
> > > > driver.)  So they dropped it.
> > > > When would you want to do this kind of rebalancing?  Before any PCI
> > > > driver is bound to any devices?  Or afterwards?
> > >
> > > I guess if we want the rebalance dynamic, then we should have it  
> > > full --
> > > the rebalance would be functional even after the driver is loaded.
> > >
> > > But in most cases, there will be problem when we unload driver  
> > > from a hard
> > > disk controller, etc. We can mount root on a ramdisk and do the  
> > > rebalance
> > > there, but it's complicated for a real user.
> > >
> > > So looks like doing rebalancing before any driver is bound to any  
> > > device is
> > > also a nice idea, if user can get a shell to do rebalance before  
> > > built-in
> > > PCI driver grabs device.
> >
> > That's not going to work, it needs to happen before any PCI device is
> > bound, which is before init runs.
>
> We could run shell from early initrd... And PCI is not required for
> initrd, right?

You can't be sure of that - compile your ATA driver =y and you'll  
definitely end up using PCI.

Alex
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