From: Thomas Huth <thuth@redhat.com>
To: "Cornelia Huck" <cohuck@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
Collin Walling <walling@linux.ibm.com>,
"open list:RISC-V" <qemu-riscv@nongnu.org>,
Eduardo Habkost <ehabkost@redhat.com>,
Sagar Karandikar <sagark@eecs.berkeley.edu>,
"Michael S. Tsirkin" <mst@redhat.com>,
Helge Deller <deller@gmx.de>, Palmer Dabbelt <palmer@sifive.com>,
Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
QEMU Developers <qemu-devel@nongnu.org>,
Aurelien Jarno <aurelien@aurel32.net>,
"open list:S390" <qemu-s390x@nongnu.org>,
qemu-arm <qemu-arm@nongnu.org>,
Alistair Francis <Alistair.Francis@wdc.com>,
Gerd Hoffmann <kraxel@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
qemu-ppc <qemu-ppc@nongnu.org>,
Richard Henderson <rth@twiddle.net>,
Artyom Tarasenko <atar4qemu@gmail.com>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [Qemu-devel] [qemu-s390x] [RFC PATCH 1/3] hw/Kconfig: PCI bus implies PCI_DEVICES
Date: Mon, 15 Jul 2019 15:19:17 +0200 [thread overview]
Message-ID: <13fce62f-234c-1b13-595f-5910c066bc4f@redhat.com> (raw)
In-Reply-To: <20190715130955.4a117388.cohuck@redhat.com>
On 15/07/2019 13.09, Cornelia Huck wrote:
> On Mon, 15 Jul 2019 13:04:28 +0200
> Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>
>> On 7/15/19 12:56 PM, Cornelia Huck wrote:
>>> On Mon, 15 Jul 2019 12:48:55 +0200
>>> Thomas Huth <thuth@redhat.com> wrote:
>>>
>>>> On 15/07/2019 12.19, Peter Maydell wrote:
>>>>> On Mon, 15 Jul 2019 at 11:15, Thomas Huth <thuth@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 <philmd@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?
Thomas
Thomas
next prev parent reply other threads:[~2019-07-15 13:19 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 9:55 [Qemu-devel] [PATCH 0/3] hw/Kconfig: PCI & USB fixes Philippe Mathieu-Daudé
2019-07-15 9:55 ` [Qemu-devel] [RFC PATCH 1/3] hw/Kconfig: PCI bus implies PCI_DEVICES Philippe Mathieu-Daudé
2019-07-15 10:15 ` Thomas Huth
2019-07-15 10:19 ` Peter Maydell
2019-07-15 10:48 ` Thomas Huth
2019-07-15 10:56 ` [Qemu-devel] [qemu-s390x] " Cornelia Huck
2019-07-15 11:04 ` Philippe Mathieu-Daudé
2019-07-15 11:09 ` Cornelia Huck
2019-07-15 13:19 ` Thomas Huth [this message]
2019-07-15 13:38 ` Philippe Mathieu-Daudé
2019-07-15 13:49 ` Thomas Huth
2019-07-15 16:08 ` Markus Armbruster
2019-07-15 16:12 ` Cornelia Huck
2019-07-15 18:22 ` Paolo Bonzini
2019-07-16 13:06 ` Markus Armbruster
2019-07-16 15:04 ` Thomas Huth
2019-07-17 12:59 ` Collin Walling
2019-07-17 13:52 ` Paolo Bonzini
2019-07-17 14:54 ` Collin Walling
2019-07-17 15:04 ` Paolo Bonzini
2019-07-18 15:33 ` Cornelia Huck
2019-07-22 13:40 ` Markus Armbruster
2019-07-15 9:55 ` [Qemu-devel] [PATCH-for-4.2 2/3] hw/usb/Kconfig: Add CONFIG_USB_EHCI_PCI Philippe Mathieu-Daudé
2019-07-15 10:54 ` [Qemu-devel] [Qemu-ppc] " BALATON Zoltan
2019-07-15 11:03 ` Thomas Huth
2019-07-15 11:10 ` BALATON Zoltan
2019-07-15 11:19 ` Thomas Huth
2019-07-15 11:20 ` Paolo Bonzini
2019-07-15 11:01 ` [Qemu-devel] " Thomas Huth
2019-07-15 9:55 ` [Qemu-devel] [PATCH-for-4.1? 3/3] hw/usb/Kconfig: USB_XHCI_NEC requires USB_XHCI Philippe Mathieu-Daudé
2019-07-15 10:50 ` Thomas Huth
2019-07-15 11:21 ` [Qemu-devel] [PATCH 0/3] hw/Kconfig: PCI & USB fixes Paolo Bonzini
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