Re: [Qemu-devel] [PATCH] hw/arm/virt-acpi-build: _CCA attribute is compulsary

[Shannon Zhao]

On 2015/11/3 16:31, Graeme Gregory wrote:
> 
> 
> On Tue, 3 Nov 2015, at 02:25 AM, Shannon Zhao wrote:
>> Hi Graeme,
>>
>> On 2015/11/2 18:39, Graeme Gregory wrote:
>>> According to ACPI specification 6.2.17 _CCA (Cache Coherency Attribute)
>>> this attribute is compulsary on ARM systems. Add this attribute to
>>> the PCI host bridges as required.
>>>
>>
>> To ACPI 5.1 this object is not compulsory and if not supplied it has
>> default value for it. But to ACPI 6.0 it must be supplied on ARM systems.
>> Regarding this change, ACPI 6.0 fixes 5.1 for this object, right?
>>
> 
> Hi Shannon, the wording in ACPI 5.1 is "On ARM based systems, the _CCA
> object must be supplied all such devices."
> 
> So is not functionally different from 6.0.
> 
Oh, I see. It's updated by 5.1 Errata 1189.

Reviewed-by: Shannon Zhao <address@hidden>

> Graeme
> 
>>> Without this the kernel will produce the error
>>> [Firmware Bug]: PCI device 0000:00:00.0 fail to setup DMA.
>>>
>>> Signed-off-by: Graeme Gregory <address@hidden>
>>> ---
>>>  hw/arm/virt-acpi-build.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
>>> index 1aaff1f..1430125 100644
>>> --- a/hw/arm/virt-acpi-build.c
>>> +++ b/hw/arm/virt-acpi-build.c
>>> @@ -180,6 +180,7 @@ static void acpi_dsdt_add_pci(Aml *scope, const 
>>> MemMapEntry *memmap, int irq,
>>>      aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
>>>      aml_append(dev, aml_name_decl("_UID", aml_string("PCI0")));
>>>      aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
>>> +    aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
>>>  
>>>      /* Declare the PCI Routing Table. */
>>>      Aml *rt_pkg = aml_package(nr_pcie_buses * PCI_NUM_PINS);
>>>
>>
>> -- 
>> Shannon
>>
>>

-- 
Shannon