[SeaBIOS] [Qemu-devel] [PATCH v4 for-2.3 13/25] hw/acpi: remove from root bus 0 the crs resources used by other busses.

[Stefan Hajnoczi]

On Mon, Mar 09, 2015 at 09:44:24AM +0100, Michael S. Tsirkin wrote:
> On Sun, Mar 08, 2015 at 02:46:28PM -0400, Kevin O'Connor wrote:
> > On Sun, Mar 08, 2015 at 07:34:34PM +0100, Michael S. Tsirkin wrote:
> > > On Sun, Mar 08, 2015 at 12:13:40PM -0400, Kevin O'Connor wrote:
> > > > If I read this correctly, it looks like a machine with two root buses
> > > > and 20 devices, each with one memory range and one io range, would end
> > > > up with 40 CRS ranges (ie, a CRS range for every resource).
> > > 
> > > I think that's only if you stick multiple devices directly behind the
> > > bridge.  Looks like with a single pci bridge behind root, there will
> > > only be 2 ranges.
> > 
> > Yeah, that makes sense, so doesn't seem to be a problem.
> > 
> > > Maybe try to enforce this sane topology?
> > > 
> > > > It also
> > > > looks like this furthers the requirement that the guest firmware
> > > > assign the PCI resources prior to QEMU being able to generate the ACPI
> > > > tables.
> > > 
> > > That seems unavoidable unless we want to assign ranges from
> > > hardware/management.
> > > Which I think would be a mistake: management doesn't really know,
> > > or care.
> > 
> > I understand.  I think what would help me is if we could document
> > somewhere that the firmware has to assign PCI resources before
> > querying the bios tables and that it is the *only* pre-requisite for
> > querying them.  Looking now, though, I don't see any fw_cfg
> > documentation in the repo, so I'm not sure where that could be added.
> > 
> > Thanks,
> > -Kevin
> 
> Sigh. Might make a GSoC project?

Documentation projects are not possible under Google Summer of Code:

https://www.google-melange.com/gsoc/document/show/gsoc_program/google/gsoc2015/help_page#12._Are_proposals_for_documentation_work

If there is a coding project you are interested in mentoring, there is a
project idea template to fill out here:

http://qemu-project.org/Google_Summer_of_Code_2015#Project_idea_template

Stefan
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