Re: [Qemu-devel] [PATCH] hw/pxb-pcie: fix PCI Express hotplug support

[Marcel Apfelbaum]

On 02/03/2017 12:34 AM, Michael S. Tsirkin wrote:
> On Fri, Feb 03, 2017 at 12:05:52AM +0200, Marcel Apfelbaum wrote:
> > Add the missing osc method for pxb-pcie devices
> >
> > Signed-off-by: Marcel Apfelbaum <address@hidden>
> > ---
> >
> > Note: The patch is based on the fact that Q35's osc method is quite generic.
> >
> > Thanks,
> > Marcel
> >
> >  hw/i386/acpi-build.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index 1c928ab..555aab3 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -1964,6 +1964,11 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> >              aml_append(dev, aml_name_decl("_UID", aml_int(bus_num)));
> >              aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
> >              aml_append(dev, aml_name_decl("_BBN", aml_int(bus_num)));
> > +            if (pci_bus_is_express(bus)) {
> > +                aml_append(dev, aml_name_decl("SUPP", aml_int(0)));
> > +                aml_append(dev, aml_name_decl("CTRL", aml_int(0)));
> > +                aml_append(dev, build_q35_osc_method());
> > +            }

Hi Michael,
Thanks for the review.

> I think we want to move this stuff into build_q35_osc_method:
> "SUPP" seems to be 0, CTRL should be a variable passed in.

Sure

> >              if (numa_node != NUMA_NODE_UNASSIGNED) {
> >                  aml_append(dev, aml_name_decl("_PXM", aml_int(numa_node)));
>
>
> In fact build_q35_osc_method needs to be cleaned up.
> It stores result in "CTRL" which should be documented.
>
> "SUPP" seems to be unused.
>
> A bunch of comments missing.
>
> More importantly, its an unserialized method but it creates a bunch of
> fields so attempts to run two of these in parallel will crash.

I don't see how this code will run in parallel. (the code that calls the _OSC 
method)

> I see the same in ACPI spec which probably means it should be
> revisited with a critical eye.

I am in PTO next week, then I'll revisit the build_q35_osc_method and (try to) 
clean it up.

Thanks,
Marcel

> > --
> > 2.5.5