linux-kernel - Re: [PATCH 2/2] PCI, ACPI, x86: update MMCFG information when hot-plugging PCI host bridges

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Message-ID: <CAE9FiQXsbSikFYuTECH7QbHLxFOA1uZ-=oC_v6-7fzdC4V0PSA@mail.gmail.com>
Date:	Mon, 9 Apr 2012 08:11:05 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Jiang Liu <liuj97@...il.com>
Cc:	Taku Izumi <izumi.taku@...fujitsu.com>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Jiang Liu <jiang.liu@...wei.com>,
	Keping Chen <chenkeping@...wei.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 2/2] PCI, ACPI, x86: update MMCFG information when
 hot-plugging PCI host bridges

On Mon, Apr 9, 2012 at 7:37 AM, Jiang Liu <liuj97@...il.com> wrote:
> Hi Yinghai,
>
>>> +int arch_acpi_pci_root_remove(struct acpi_pci_root *root)
>>> +{
>>> +       acpi_status status;
>>> +       unsigned long long base_addr;
>>> +
>>> +       /* Remove MMCFG information for host bridges with _CBA method */
>>> +       status = acpi_evaluate_integer(root->device->handle, METHOD_NAME__CBA,
>>> +                                      NULL, &base_addr);
>>
>> add one flag in acpi_pci_root about we added mmconf for it before?
>> like mmconf_added?
>>
>
> I feel adding a flag here doesn't help here. For any hot-pluggable PCI host bridge
> with _CBA method available, arch_acpi_pci_root_remove() should delete the MMCFG
> information, no matter it's added by __pci_mmcfg_init() or arch_acpi_pci_root_add().
> So check existence of _CBA seems simpler here.

_remove should not care about _CBA, it should only care about if it
gets added on _add path.

Also like Kenji said, We should let it go through even no MMCONF is
added at that time.
like somehow _CBA does not exis for some root bus or evaluating failing etc.

Yinghai
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