On Tue, Jan 17, 2012 at 9:09 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> On Tue, Jan 17, 2012 at 4:41 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>> Host bridges that lead to things like the Uncore need not have any
>> I/O port or MMIO apertures. For example, in this case:
>>
>> ACPI: PCI Root Bridge [UNC1] (domain 0000 [bus ff])
>> PCI: root bus ff: using default resources
>> PCI host bridge to bus 0000:ff
>> pci_bus 0000:ff: root bus resource [io 0x0000-0xffff]
>> pci_bus 0000:ff: root bus resource [mem 0x00000000-0x3fffffffffff]
>>
>> we should not pretend those default resources are available on bus ff.
>>
>> CC: Yinghai Lu <yinghai@xxxxxxxxxx>
>> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>> ---
>> arch/x86/pci/acpi.c | 7 ++++++-
>> 1 files changed, 6 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
>> index 0a45d1c..67d9b49 100644
>> --- a/arch/x86/pci/acpi.c
>> +++ b/arch/x86/pci/acpi.c
>> @@ -405,7 +405,12 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
>> kfree(sd);
>> } else {
>> get_current_resources(device, busnum, domain, &resources);
>> - if (list_empty(&resources))
>> +
>> + /*
>> + * _CRS with no apertures is normal, so only fall back to
>> + * defaults or native bridge info if we're ignoring _CRS.
>> + */
>> + if (!pci_use_crs)
>> x86_pci_root_bus_resources(busnum, &resources);
>> bridge = pci_create_host_bridge(NULL, domain, &root->secondary,
>> &resources, &pci_root_ops, sd);
>>
>
> how about system with ACPI support, but does not have _CRS or _CRS has
> parse error ?
Do you have examples of such systems? I haven't seen any, and I'm not
sure it's worth worrying about them unless they actually exist.
It doesn't seem like it would make any sense to use ACPI to describe a
host bridge without using _CRS to describe its properties.
Bjorn
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