From: Bjorn Helgaas <helgaas@kernel.org>
To: Rui Wang <rui.y.wang@intel.com>
Cc: tglx@linutronix.de, rjw@rjwysocki.net, tony.luck@intel.com,
bhelgaas@google.com, linux-acpi@vger.kernel.org,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot
Date: Thu, 16 Jun 2016 12:09:59 -0500 [thread overview]
Message-ID: <20160616170958.GA7250@localhost> (raw)
In-Reply-To: <1465711569-19406-1-git-send-email-rui.y.wang@intel.com>
On Sun, Jun 12, 2016 at 02:06:09PM +0800, Rui Wang wrote:
> On Saturday, June 11, 2016 12:43 AM, Bjorn Helgaas wrote:
> > On Wed, Jun 08, 2016 at 05:32:44PM +0800, Rui Wang wrote:
> > > @@ -1779,8 +1780,12 @@ void __init
> > > pci_assign_unassigned_resources(void)
> > > {
> > > struct pci_bus *root_bus;
> > >
> > > - list_for_each_entry(root_bus, &pci_root_buses, node)
> > > + list_for_each_entry(root_bus, &pci_root_buses, node) {
> > > pci_assign_unassigned_root_bus_resources(root_bus);
> > > +#ifdef CONFIG_X86
> > > + acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> > > +#endif
> >
> > This seems like a strange place to call acpi_ioapic_add(). Your object is to call
> > acpi_ioapic_add() during root bus enumeration.
> >
> > I assume we *can't* call acpi_ioapic_add() from acpi_pci_root_add() at boot
> > time, for some reason you'll explain. But is there a reason we have to call it
> > from pci_assign_unassigned_resources() (where it requires an ifdef) instead
> > of from pcibios_assign_resources(), which is already x86-specific?
> >
> > In acpi_pci_root_add(), we have this:
> >
> > acpi_pci_root_add(...)
> > {
> > ...
> > if (hotadd)
> > acpi_ioapic_add(root);
> >
> > So the obvious question is why don't we just remove the "if (hotadd)"
> > and call acpi_ioapic_add() always.
> >
> > I'm sure the reason is some ordering problem, but we need a comment in
> > acpi_pci_root_add() about why the obvious solution doesn't work.
>
> Yes it's an ording issue. acpi_ioapic_add() and also ioapic_insert_resources()
> have to be later than pci initialization in order to deal with IOAPICs mapped
> on a PCI BAR. There's a comment about this inside pcibios_resource_survey()
> above ioapic_insert_resources(). We can also add a comment inside
> acpi_pci_root_add(), though.
>
> And yes calling acpi_ioapic_add() in pcibios_assign_resources() doesn't require
> ifdef CONFIG_X86. But it'll require a loop to iterate through the root buses,
> and call acpi_ioapic_add() within the loop. pci_assign_unassigned_resources()
> already has that loop. Do you still prefer adding it to
> pcibios_assign_resources() ?
ioapic_insert_resources() is x86-specific, but I'm not sure why; it
seems like it does things that should be applicable to ia64 as well.
acpi_ioapic_add() is not x86-specific, and it is called from
acpi_pci_root_add() for the hot-add case. You're adding an
x86-xpecific call in pci_assign_unassigned_resources(). Why should
the hot-add case be for all arches, but the boot-time case only for
x86?
next prev parent reply other threads:[~2016-06-16 17:10 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-08 6:59 [PATCH V2 0/3] ioapic hot-removal bugs Rui Wang
2016-06-08 6:59 ` [PATCH V2 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot Rui Wang
2016-06-08 8:05 ` kbuild test robot
2016-06-08 9:32 ` [PATCH V3 " Rui Wang
2016-06-10 12:57 ` Thomas Gleixner
2016-06-10 13:56 ` Rafael J. Wysocki
2016-06-10 16:43 ` Bjorn Helgaas
2016-06-12 6:06 ` Rui Wang
2016-06-16 17:09 ` Bjorn Helgaas [this message]
2016-06-22 7:13 ` Rui Wang
2016-06-22 14:53 ` Bjorn Helgaas
2016-06-24 15:18 ` Rui Wang
2016-06-22 7:40 ` [PATCH V4 " Rui Wang
2016-06-22 15:14 ` Bjorn Helgaas
2016-06-23 5:11 `
2016-06-23 17:34 ` Bjorn Helgaas
2016-06-24 15:30 ` Rui Wang
2016-06-26 3:44 ` [PATCH V5 " Rui Wang
2016-08-08 20:22 ` Bjorn Helgaas
2016-08-09 3:23 ` Rui Wang
2016-08-09 12:09 ` Rafael J. Wysocki
2016-06-08 6:59 ` [PATCH V2 2/3] x86/ioapic: Fix wrong pointers in ioapic_setup_resources() Rui Wang
2016-06-10 9:45 ` [tip:x86/urgent] " tip-bot for Rui Wang
2016-06-10 12:01 ` [tip:x86/apic] x86/ioapic: Fix incorrect " tip-bot for Rui Wang
2016-06-10 12:48 ` [tip:x86/urgent] " tip-bot for Rui Wang
2016-06-08 6:59 ` [PATCH V2 3/3] x86/ioapic: Simplify ioapic_setup_resources() Rui Wang
2016-06-10 9:48 ` [tip:x86/apic] " tip-bot for Rui Wang
2016-06-10 12:54 ` tip-bot for Rui Wang
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