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Re: [Qemu-ppc] [Qemu-devel] [PATCH v2 10/14] pci: allow 0 address for PC
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From: |
Benjamin Herrenschmidt |
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Subject: |
Re: [Qemu-ppc] [Qemu-devel] [PATCH v2 10/14] pci: allow 0 address for PCI IO regions |
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Date: |
Wed, 11 Dec 2013 10:03:21 +1100 |
On Tue, 2013-12-10 at 22:14 +0000, Peter Maydell wrote:
> Googling again brought up this mailing list thread:
>
> http://www.pcisig.com/reflector/msg00459.html
>
> which includes what is supposedly a quote from the PCI 2.1 spec:
>
> # "Note: A Base Address register does not contain a valid
> # address when it is equal to "0""
>
> (I don't have access to the 2.1 version to check.)
>
> This text seems to have been removed from the 2.2 spec.
I have seen practical cases of both:
- Systems where the FW sets up a BAR to 0 and considers it valid
- Adapters that treat a BAR set to 0 as disabled
There's no win here. However it makes sense for qemu not to treat 0
as a special value, it's not necessary.
Cheers,
Ben.
- Re: [Qemu-ppc] [PATCH v2 05/14] spapr_pci: add get/set-power-level RTAS interfaces, (continued)
- [Qemu-ppc] [PATCH v2 07/14] spapr_pci: add ibm, configure-connector RTAS interface, Michael Roth, 2013/12/05
- [Qemu-ppc] [PATCH v2 06/14] spapr_pci: add get-sensor-state RTAS interface, Michael Roth, 2013/12/05
- [Qemu-ppc] [PATCH v2 03/14] spapr: add helper to retrieve a PHB/device DrcEntry, Michael Roth, 2013/12/05
- [Qemu-ppc] [PATCH v2 02/14] spapr_pci: populate DRC dt entries for PHBs, Michael Roth, 2013/12/05
- [Qemu-ppc] [PATCH v2 09/14] pci: make pci_bar useable outside pci.c, Michael Roth, 2013/12/05
- [Qemu-ppc] [PATCH v2 10/14] pci: allow 0 address for PCI IO regions, Michael Roth, 2013/12/05
- Re: [Qemu-ppc] [PATCH v2 10/14] pci: allow 0 address for PCI IO regions, Michael S. Tsirkin, 2013/12/12
[Qemu-ppc] [PATCH v2 08/14] memory: add memory_region_find_subregion, Michael Roth, 2013/12/05
[Qemu-ppc] [PATCH v2 11/14] spapr_pci: enable basic hotplug operations, Michael Roth, 2013/12/05
[Qemu-ppc] [PATCH v2 14/14] spapr_pci: emit hotplug add/remove events during hotplug, Michael Roth, 2013/12/05
[Qemu-ppc] [PATCH v2 13/14] spapr_events: event-scan RTAS interface, Michael Roth, 2013/12/05
[Qemu-ppc] [PATCH v2 12/14] spapr_events: re-use EPOW event infrastructure for hotplug events, Michael Roth, 2013/12/05