Re: [Xen-devel] vBAR=pBAR - Dynamically Generating DSDT?

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-07-03 at 12:42 +0100, Gordan Bobic wrote:
>  On Wed, 03 Jul 2013 07:33:56 -0400, Konrad Rzeszutek Wilk 
>  <konrad.wilk@xxxxxxxxxx> wrote:
> > Gordan Bobic <gordan@xxxxxxxxxx> wrote:
> >
> >> I'm looking at the 2009 era patches for vBAR=pBAR and
> >> the more recent maintained version at davidgis.fr,
> >> and it would appear that the BAR spaces get hard-coded.
> >>
> >> Is there a reason why this cannot be dynamically
> >> generated at domU start time? I could write a
> >> wrapper easily enough to doctor this every time
> >> I need to start a VM that generates a patch for
> >> the relevant devices and recompiles hvmloader,
> >> but this is quite a horrible way to do this.
> >
> > Could it be done via Xen Store?  hvmloader is already capable of
> > reading values from there.  Perhaps add a new attribute there?  In
> > local/domain/0/vpci/<domain>/pbar-<bdf>?
> 
>  Considering xenstore seems to be deprecated for
>  storing domU configs in favour of plain text files

Uhm, what?

domU configs have never been stored in xenstore.

xenstore is a runtime service used for communicating configuration
information between different bits of the system and serving as a
rendevous point for different parts of the system (e.g. front and
backends, toolstack and hvmloader, toolstack and itself).

>  (Windows registry, anyone?), I'm weary of going
>  down the route of anything touching the xenstore.
>  If it's still going to be hard-coded, I'd rather
>  having it in the domU config file.

...from where it should be written to xenstore when creating the domain
in order to communicate to hvmloader where things should go.

> 
>  Detecting all the BARs from all the assigned PCI
>  devices at domU initialization time would be
>  better, though...
> 
>  Gordan
> 
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