On Mon, 15 Jul 2019 18:08:45 +0200 Markus Armbruster <arm...@redhat.com> wrote:
> Philippe Mathieu-Daudé <phi...@redhat.com> writes: > > > On 7/15/19 3:19 PM, Thomas Huth wrote: > >> On 15/07/2019 13.09, Cornelia Huck wrote: > >>> On Mon, 15 Jul 2019 13:04:28 +0200 > >>> Philippe Mathieu-Daudé <phi...@redhat.com> wrote: > >>> > >>>> On 7/15/19 12:56 PM, Cornelia Huck wrote: > >>>>> On Mon, 15 Jul 2019 12:48:55 +0200 > >>>>> Thomas Huth <th...@redhat.com> wrote: > >>>>> > >>>>>> On 15/07/2019 12.19, Peter Maydell wrote: > >>>>>>> On Mon, 15 Jul 2019 at 11:15, Thomas Huth <th...@redhat.com> wrote: > >>>>>>> > >>>>>>>> > >>>>>>>> On 15/07/2019 11.55, Philippe Mathieu-Daudé wrote: > >>>>>>>>> If a controller device provides a PCI bus, we can plug any PCI > >>>>>>>>> daughter card on it. > >>>>>>>>> > >>>>>>>>> Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> > >>>>>>>>> --- > >>>>>>> > >>>>>>>>> diff --git a/hw/pci/Kconfig b/hw/pci/Kconfig > >>>>>>>>> index 77f8b005ff..0f7267db35 100644 > >>>>>>>>> --- a/hw/pci/Kconfig > >>>>>>>>> +++ b/hw/pci/Kconfig > >>>>>>>>> @@ -1,5 +1,6 @@ > >>>>>>>>> config PCI > >>>>>>>>> bool > >>>>>>>>> + imply PCI_DEVICES > >>>>>>>> > >>>>>>>> No, please don't change this. This was done on purpose, since almost > >>>>>>>> all > >>>>>>>> PCI_DEVICES do not work on s390x (so s390x does *not* imply > >>>>>>>> PCI_DEVICES). > >>>>>>> > >>>>>>> But that means that every board that provides PCI has to have an > >>>>>>> "imply PCI_DEVICES" line, which is pretty clunky just to work > >>>>>>> around an s390x limitation. > >>>>>>> > >>>>>>> Is there some way in the Kconfig syntax for s390x to say > >>>>>>> "no PCI_DEVICES" so we can have the corner-case be handled > >>>>>>> by the s390x Kconfig in one place rather than in 20 places > >>>>>>> affecting everywhere except s390x? > >>>>>> > >>>>>> IIRC the problem on s390x are the legacy IRQs. s390x has only MSIs. So > >>>>>> I > >>>>>> guess the correct way to fix this would be to introduce some > >>>>>> PCI_LEGACY_IRQ switch and let all old devices that do not work with MSI > >>>>>> depend on it. > >>>>> > >>>>> s/MSI/MSI-X/, IIRC. Not sure how far 'legacy' would stretch. > >>>> > >>>> Maybe we can have something like PCI_LEGACY_DEVICES and PCI_MSI_DEVICES? > >>>> > >>>> So if s390x only selects PCI_LEGACY (not PCI_MSI) bus, then it only get > >>>> legacy devices? > >>> > >>> Wrong way around? We need MSI-X for s390x, not plain MSI or > >>> 'legacy' (whatever that is). > >> > >> With "legacy" I meant the old level-triggered interrupts from the early > >> PCI (non-express) days. Sorry for being imprecise here. > >> > >> So maybe we need two new switches, PCI_CLASSIC (or so) and PCI_MSIX, and > >> then the PCI devices should be marked with "default y if PCI_CLASSIC" if > >> they do not have MSIX support, and with "default y if PCI_MSIX" if they > >> have MSI-X support? > > > > Something like that :) > > > > Per Wikipedia: > > > > Conventional PCI and PCI-X are sometimes called Parallel PCI > > in order to distinguish them technologically from their more > > recent successor PCI Express, which adopted a serial, > > lane-based architecture. > > > > The PCI-SIG introduced the serial PCI Express in c. 2004. At > > the same time, they renamed PCI as Conventional PCI. > > > > PCI Express does not have physical interrupt lines at all. > > It uses message-signaled interrupts exclusively. > > > > What about PCI_CONVENTIONAL then? > > What kinds of PCI devices are we trying to name? > > Is it INTx vs. MSI vs. MSI-X? I think for s390x we need (INTx || MSI) vs MSI-X... > > Is it Conventional PCI vs. PCI Express? ...while this is probably more INTx vs (MSI || MSI-X)?
