Groups > linux.kernel > #1208483

Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux,pci-probe-only property

From	Will Deacon <will.deacon@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux,pci-probe-only property
Date	2015-08-17 11:10 +0200
Message-ID	<pYoAy-2Ok-11@gated-at.bofh.it> (permalink)
References	<pXpS2-79Q-5@gated-at.bofh.it> <pXpS2-79Q-9@gated-at.bofh.it> <pXql4-7I3-17@gated-at.bofh.it> <pXql4-7I3-19@gated-at.bofh.it> <pXtLY-4kb-19@gated-at.bofh.it>
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On Fri, Aug 14, 2015 at 09:26:21PM +0100, Bjorn Helgaas wrote:
> On Fri, Aug 14, 2015 at 11:43 AM, Will Deacon <will.deacon@arm.com> wrote:
> > On Fri, Aug 14, 2015 at 05:40:51PM +0100, Bjorn Helgaas wrote:
> >> Do we need support for pci-probe-only in pci-host-generic at all?
> >> You're removing the use in amd-overdrive.dts, and there are no other
> >> DTs in the kernel tree that mention it.
> >>
> >> If we can live without it, that would be nice.  It seems like a relic from
> >> days when we couldn't reliably assign resources.  (I'm not saying we can do
> >> that reliably even today, but I'd rather make it reliable than turn it
> >> off.)
> >
> > Kvmtool certainly uses it (and generates its own DT, hence why you don't
> > see it in mainline). Not sure about qemu, though.
> 
> Do you know why kvmtool wants probe-only?  Would something break if we
> didn't support probe-only?  I guess we'd be looking for a case where
> Linux assigns resources and that assignment doesn't work with kvmtool?

It's basically because the BARs aren't writable other than to find the
region size. It could fixed with a bit of pain, but it doesn't help older
kvmtools that do work with mainline today.

Will
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Thread

[PATCH v2 0/4] PCI: arm64/powerpc: Fix parsing of linux,pci-probe-only Marc Zyngier <marc.zyngier@arm.com> - 2015-08-14 18:20 +0200
  [PATCH v2 4/4] arm64: dts: Drop linux,pci-probe-only from the Seattle DTS Marc Zyngier <marc.zyngier@arm.com> - 2015-08-14 18:20 +0200
  [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux,pci-probe-only property Marc Zyngier <marc.zyngier@arm.com> - 2015-08-14 18:20 +0200
    Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of  linux,pci-probe-only property Will Deacon <will.deacon@arm.com> - 2015-08-14 18:50 +0200
    Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of  linux,pci-probe-only property Bjorn Helgaas <bhelgaas@google.com> - 2015-08-14 18:50 +0200
      Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of  linux,pci-probe-only property Will Deacon <will.deacon@arm.com> - 2015-08-14 18:50 +0200
        Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux,pci-probe-only property Alexander Graf <agraf@suse.de> - 2015-08-14 19:00 +0200
        Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of  linux,pci-probe-only property Bjorn Helgaas <bhelgaas@google.com> - 2015-08-14 22:30 +0200
          Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of  linux,pci-probe-only property Will Deacon <will.deacon@arm.com> - 2015-08-17 11:10 +0200
  [PATCH v2 1/4] of/pci: Add of_pci_check_probe_only to parse "linux,pci-probe-only" Marc Zyngier <marc.zyngier@arm.com> - 2015-08-14 18:20 +0200
    Re: [PATCH v2 1/4] of/pci: Add of_pci_check_probe_only to parse "linux,pci-probe-only" Rob Herring <robherring2@gmail.com> - 2015-08-14 23:10 +0200
  [PATCH v2 3/4] powerpc: PCI: Fix lookup of linux,pci-probe-only property Marc Zyngier <marc.zyngier@arm.com> - 2015-08-14 18:30 +0200

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